Meuzelaar, HLC

1996

On-Line GC/MS Techniques for Monitoring High-Pressure Conversion Reactions

Jakab, E.; Huai, H.; Nie, H. and Meuzelaar, H.L.C.
Process Control & Quality, 8:55-67, 1996. Funded by Consortium for Fossil Fuel Liquefaction Science, ACERC and Rocketdyne.

Gas chromatography-mass spectrometry instruments were interfaced to high-pressure flow-through microreactors to monitor the product formation on-line. Three types of instrumental setup are described illustrating the versatility of this kind of coupling. The first example shows the thermal and catalytic conversion of dibenzyl ether in solution under 155 bar hydrogen atmosphere. In the second application, thermal decomposition of JP-7 jet fuel was carried out under supercritical conditions to study the gaseous product evolution. This system features the application of a microbalance to monitor the weight of the total liquid sample plus products. The third system was designed to perform conversion of solid sample (wood) in liquid/vapor environment. This reactor can be applied to model two-step liquefaction processes with catalytic conversion of the primary product. All three systems provide information on the product distribution and kinetic profiles of the conversion processes.

Catalytic Reactions in Waste Plastics, HDPE and Coal Studies by High-Pressure Thermogravimetry with On-Line GC/MS

Liu, K. and Meuzelaar, H.L.C.
Fuels Processing, 49:55-67, 1996. Funded by Consortium for Fossil Fuel Liquefaction Science.

High pressure thermogravimetry (TG) with rapid on-line gas chromatography/mass spectrometry (GC/MS) has been used to investigate the effects of different catalysts on decomposition reactions of commingled wasted plastics (predominately PE), high density polyethylene (HDPE) and mixtures of DECS-6 with waste plastics in H2 at 900 psig. This permits direct evaluation of relative decomposition and residual char amounts as well as yield and include solid super acids such as Fe2O3/SO42-, Al2O3/SO, Al2O3/SO42- promoted by 0.5% Pt, and ZrO2/SO42- (all added at 10 wt%), as well as a conventional cracking catalyst of SiO2/Al2O3 in a 4:1 ratio, a hydrocracking catalyst of NiMo/Al2O3, HZSM-5>NiMoAl2O3 mixed with SiO2 Al2O3> (both added at 50%), and a HZSM-5 zeolite catalyst (added at 10%). Under these conditions cracking activity for waste plastics reveals the following order: SiO2/Al2O3, HZSM-5>NiMo/Al mixed with Si2O3O2Al2O3 solid super acids. Of the solid super acids studied the ZrO2/SO42- catalyst possesses the highest cracking activity, and the approximate order of cracking activity is ZrO2/SO42- > Al2O3/SO42- > Pt/Al2O3/SO42- > Fe2O3/SO42->no catalyst. The stronger the cracking catalyst, the lighter the aliphatic products and the more abundant the isometric constituents. Similar results are found for HDPD with these catalysts. For co-processing of coal with commingled waste plastic the HZSM-5 zeolite catalyst shows the most promising results by increasing the rate of the decomposition reactions at 420ºC nearly tenfold. Hydrocracking catalysts, such as NiMo/Al2O3 mixed with SiO2/Al2O3, show potential promise for processing of coal with commingled waste plastic due to their combined hydrogenation and cracking ability. By contrast, a superacid such as ZrO2/SO42- or cracking catalyst such as SiO2/Al2O3 appears to have little effect on the decomposition rate of the mixture. To what extent these findings are influenced by transport limitations (e.g., due to incomplete mixing or degree of crystallinity) and/or catalyst pretreatment is being studied further.

Detection of the Picolinic Acid Biomarker in Bacillus Spores Using a Potentially Field-Portable Pyrolysis-Gas Chromatography-Ion Mobility Spectrometry System

Snyder, A.P.; Thornton, S.; Dworzanski, J.P. and Meuzelaar, H.L.C.
Field Analytical Chemistry and Technology, 1:49-58, 1996. Funded by US Army Research Office.

The absence of a field-portable device to provide real-time detection of Gram-positive bacterial spores has prompted the interfacing of a pyrolysis (Py) module to an existing, hand-held gas-chromatography-ion-mobility spectrometry (GC/IMS) device. In this configuration, spore detection is achieved by the observation of picolinic (2-pyridinecarboxylic) acid (PA), which is the most characteristic pyrolysis decomposition product of the parent dipicolinic (2,6-pyridinedicarboxylic) acid (DPA). Positive identification of PA was demonstrated using a laboratory-based GC instrument with dual, parallel mass spectrometry (MS) and IMS detectors. Spores and vegetative microorganisms of the genus Bacillus were characterized by the presence and absence of DPA, respectively, and the picolinic acid marker was identified from the GC/IMS and GC/MS profiles. A field-portable prototype Py-GC/IMS system is described and appears to provide similar bioanalytical information with respect to the laboratory-based system. Preliminary results of this study indicate that the degree of compound separation afforded by a short GC capillary column guards against common environmental interferences including urban particulate matter and biological particles such as fungal spores and pollen.

Roving GC/MS: Mapping VOC Gradients and Trends in Space and Time

McClennen, W.H.; Vaughn, C.L.; Cole, P.A.; Sheya, S.A.N.; Wager, D.J.; Mott, T.J.; Dworzanski, J.P.; Meuzelaar, H.L.C. and Arnold, N.S.
Field Analytical Chemistry and Technology, 1(2):109-116, 1996. Funded by Hewlett Packard and ACERC.

Obtaining representative VOC (volatile organic compound) measurements in ambient environments that exhibit complex concentration gradients and/or trends is difficult when relying upon limited numbers of analyses obtained by simple pooling or averaging techniques. A more effective approach is to perform large numbers of analyses over a period of time to permit detailed mapping of profiling of local gradients and trends. Until recently, use of GC/MS (gas chromatography/mass spectrometry) techniques for rapid profiling or mapping operations was not feasible because of sample speed limitations. This article describes a roving GC/MS system based on the combination of a Hewlett-Packard model 5972 MSD (mass selective detector), a FemtoScan Enviroprobe repetitive vapor sampling inlet with short capillary GC column, and Alcatel Micro HV oil-less vacuum pump stack and a Pentium notebook PC running under Windows 95. The roving system is further equipped with differential GPS (global positioning system) and radio transceiver capabilities thereby permitting remote tracking of vehicle location and local VOC concentrations. Laboratory tests demonstrate lower detection limits of approx 4 ppb for BTX (benzene, toluene, and zylene), corresponding to minimum detectable quantities of a mixture of volatile ketones. Demonstrated outdoor performance, using a zero-emission electric vehicle, includes measurement of low ppb BTX levels along a 6 km urban route at 15 s (~ 150 m) intervals while moving at an estimated average speed of 35 km/hr. Indoor measurements of toluene concentrations in the low to mid ppm range at 6 s (~5 cm) intervals along a 6 m long path reveal a high degree of spatial and temporal variability in VOC concentrations. Mobility, specificity, sensitivity and speed of the roving GC/MS method make this a promising candidate method for rapid outdoor and indoor screening, monitoring and mapping of VOCs.

Field Evaluation of a Prototype Man-Portable GC/MS

Arnold, N.S.; Du, W.H.; Sheya, S.A.N.; Mihamou, H.; Dworzanski, J.P.; Hall, D.L.; McClennen, W.H. and Meuzelaar, H.L.C.
Proceedings of the Ninth International Symposium On Field Screening Methods for Hazardous Wastes and Toxic Chemicals, 2:903-910, 1996. Funded by ACERC, US Army Electrical Research Development and Engineering Center.

In recent years, a man-portable gas chromatography/mass spectrometry (GC/MS) system has been developed based on a Hewlett-Packard 5971 MSD and a unique automated vapor sampling (AVS) transfer-line (TL) GC system for direct sampling of ambient chemical vapors [1,2]. The vacuum system and power supplies were replaced to facilitate operation on 24 V DC batteries for up to 4 hours after startup on a transportable docking station. The gas chromatography was performed on a short (2 m) capillary column under isothermal conditions in a small oven to minimize power usage. Repetitive samples were taken at 10 to 60 s intervals using an automated vapor-sampling inlet.

In initial testing, the prototype system has been used for monitoring of gasoline vapors. Ambient levels of 6.0 ppm benzene, 4.1 ppm toluene, 0.22 ppm ethylbenzene, 1.1 ppm m-and p-xylene and 0.25 ppm 0-xylene were measured near a busy gas station. The gradient mapping or source tracking capabilities of the backpack-mounted system have also been demonstrated in tests with a simulated gasoline leak.

This paper will describe recent work to further evaluate the capabilities and limitations of the prototype system. Results will be described in terms of the practical utility of portable GC.NS for identification and quantification of unknown vapors.

Design Considerations for a Novel Miniaturized Tandem GC Method for Field Screening Applications

Sheya, S.A.N.; Dworzanski, J.P.; McClennen, W.H.; Meuzelaar, H.L.C. and Arnold, N.S.
Proceedings of the Ninth International Symposium On Field Screening Methods for Hazardous Wastes and Toxic Chemicals, 1:213-220, 1996. Funded by ACERC.

Development of a potentially field-portable tandem GC (GC/GC) method involving a novel, dynamic coupling between two short capillary GC columns-each of which is independently optimizable with regard to temperature and flow-is described. The relatively slow (5-25 sec wide), GC peaks eluting from the first (1.2 m x 530 µm) column are sampled repetitively at 1-5 sec. Intervals into the second (0.8 m x 100 µm) column. Dynamic coupling by means of fluidic AVS (Automated Vapor Sampling) technology, rater than through trap-and-desorb interfaces, reduces power requirements. Further power reduction is achieved by isothermal operation of both columns. If properly designed and optimized the sensitivity of dynamic GC/GC techniques should approach that of one-dimensional GC, depending on the type of detector used. Since a universally responsive, subambient pressure, low weight and low power detector for field-portable GC/GC has not yet been found, a Hewlett Packard MSC (Mass Selective Detector) was used throughout the present study. At a maximum scan rate of 35 spectra (over 5 amu mass range), the minimum practical GC peak width eluting from the second column is limited to approximately 100 msec. The feasibility of producing comprehensive, two-dimensional chromatograms of multicomponent mixtures, volatile compounds, including C3-C6 ketones, is demonstrated.

Hyphenated Techniques: The Next Generation of Field-Portable Analytical Instruments?

Meuzelaar, H.L.C.; McClennen, W.H.; Dworzanski, J.P.; Sheya, S.A.N.; Snyder, A.P.; Harden, C.S. and Arnold, N.S.
Proceedings of the Ninth International Symposium On Field Screening Methods for Hazardous Wastes and Toxic Chemicals, 1:38-46, 1996. Funded by ACERC, Consortium for Fossil Fuel Liquefaction Science, US Army Electrical Research Development and Engineering Center, Hewlett Packard, Finnigan MAT Corporation, and Femto Scan Corporation.

The first field-portable (i.e., transportable) hyphenated analytical instruments, including commercially available MS/MS and GC/MS systems as well as a specially built GC/MS system, were introduced during the past seven years. Since then further miniaturization and ruggedization of hyphenated systems by several laboratories has resulted in fully man-portable (backpack and briefcase style) GC/MS systems and a hand portable GC/IMS prototype. The main pitfall to be avoided in developing a hyphenated, field portable system is incompatibility between the coupled techniques. Carefully designed hyphenated techniques incorporating compatible methods such as GC and MS can provide dramatic increases in resolution and chemical specificity which may be traded for speed or sensitivity gains, if needed. Novel developments currently underway in the laboratory include roving GC/MS platforms, personalized GC/IMS devices, high speed GC/GC methods and, last but not least, Virtual Reality techniques.

1994

High Speed, Two-Wavelength Radiation Thermometry of Single Micro Particles During CO2 Laser Heating

Maswadeh, W.; Tripathi, A.; Arnold, N.S.; DuBow, J. and Meuzelaar, H.L.C.
Journal of Analytical and Appl. Pyrolysis, 28:55-70, 1994. Funded by ACERC.

A high speed, two-wavelength radiation thermometer that is capable of monitoring the surface temperature of 50-150 µm diameter particles in the 600-2000 K range at heating rates of up to 106 K/s, characteristic of pulverized coal combustion, was designed and constructed. To meet the above characteristics, special attention was paid to detector wavelength range and speed, detection electronics and optical system alignment. The thermometer was calibrated using an in-house constructed, black cavity radiation source. Spherocarb model particles, which have a more uniform size; physical properties and emissivity than coal particles, were used to demonstrate the level of short-term reproducibility attainable. Consistent, reproducible temperature-time profiles obtained for particles from different coals indicate that non-grey effects do not dominate these measurements.

The Effect of the Mobile Component on the Liquefaction Characteristic of Western Kentucky Coals

Keogh, R.A.; Hardy, R.H.; Taghizadeh, K.; Meuzelaar, H.L.C. and Davis, B.H.
Fuel Processing Technology, 37:33-52, 1994. Funded by US Department of Energy.

The mobile component of western Kentucky coals were extracted and analyzed by conventional methods and Curie-point mass spectroscopy. The liquefaction of the parent coals, extracted coals, and blends of the extracted coals plus mobile components indicated that the absence of the mobile component generally decreases the observed conversions obtained. The results also show that, in general, blending the mobile component and extracted coal also produces lower conversions than those obtained from the parent coal. These data suggest that the location of the mobile component in the pore structure of the coal is as important as the presence of the mobile component in coal conversion.

Comparison of On-Line MS Techniques for Complex Reactive Systems

Meuzelaar, H.L.C.
Proceedings of the Specialists Workshop on Applications of Free-Jet Molecular Beam Mass Spectrometric Sampling, Estes Park Center, CO, October 1994, and the 25th International Symposium on Combustion, Irvine, CA, Jul-Aug, 1994. Funded by ACERC and the Consortium for Fossil Fuels Liquefaction Science.

Using mass spectrometry as an on-line analytical method for studying the mechanisms and kinetics of reaction processes requires detailed awareness of various reaction/interaction/transport zones between the point of reaction and the point of ionization. The following zones (regimes, regions) can be more or less clearly recognized in most on-line MS studies of reactions in complex solids: (1) intramolecular; (2) intermolecular; (3) intraparticle; (4) interparticle (bed); (5) reactor (headspace); (6) pressure reduction; and (7) ionization. In an ideal, on-line system all products, intermediates and precursors of interest should reach the ionization region without selective losses, chemical degradation or unwanted background contributions. In practice, various secondary reactions occur well past zone 2, often resulting in chemical degradation of target analytes. Furthermore, marked losses of low volatile and/or highly polar compounds are likely to occur between reaction and ionization regions unless potential coal spots and/or active surfaces are carefully eliminated. Finally, unwanted background contributions for residues of previous runs and/or ubiquitous contaminants may originate anywhere between zones 5 and 7.

Studies of Thermal and Catalytic Hydroliquefaction of Model Compounds, Waste Polymers, and Coal by High-Pressure TG/GC/MS

Liu, K.; Jakab, E.; Zmierczak, W.; Shabtai, J.S. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 39(2):576-580, 1994. (Proceedings of the ACS National Meeting, and the 17th Annual Symposium of the Rocky Mountain Fuels, Golden, CO, March 1994 and the ACS Meeting, Division of Fuel Chemistry, San Diego, CA, March 1994.) Funded by ACERC and the Consortium for Fossil Fuels Liquefaction Science.

A recently developed on-line high-pressure themogravimetry (TG)/gas chromatography (GC)/mass spectrometry (MS) system provides certain advantages over other on-line analysis techniques for high-pressure reactors reported previously. The high pressure TG/GC/MS system enables the simulation of solvent-free thermal and catalytic reactions for polymers and coal. During the reactions the total weight change is monitored and the volatile intermediate products are identified. It requires only very small amounts (10-100 mg) of sample and can be operated at high pressure under different atmospheres (N2, He, H2, etc.). Current efforts to recycle lower grade post consumer polymers such as colored polyethylene and polystyrene or used rubber tires, are concentrated on co-processing with coal. Purely thermal degradation processes involve both decomposition and condensation (recombination) reactions and the resulting product is highly olefinic and often aromatic. In order to improve the yield and selectivity of the process, a great deal of effort has been spent on finding the proper catalysts. Catalysts selected for the present studies include ZrO2/SO4, (NH4)2MoS4 and carbon black. Carbon black present in waste rubber tires has been reported to be very selective for the cleavage of specific alkylaryl bonds. (NH4)2MoS4 has been shown to improve the liquid yields in coal liquefaction. The superacid catalyst Zr2O2/SO4 possesses markedly higher hydrogenolytic activity compared to that of conventional SiO2-supported soluble Fe salts.

Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques

Nie, X.; Liu, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 39(2):558-563, 1994. (Also presented at the 17th Annual Symposium of the Rocky Mountain Fuels Society, Golden, CO, March 1994, and at the ACS Meeting, San Diego, CA, March 1994.) Funded by ACERC and the Consortium for Fossil Fuel Liquefaction Science.

During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure.

The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.

Role of On-Line Mass Spectrometry for Studying the Structure/Reactivity Relationships and Conversion Processes of Coal

Meuzelaar, H.L.C.
ACS Preprints, Div. Of Fuel Chemistry, 39(2):36-41, 1994. (Also presented at the ACS Symposium: Division of Fuel Chemistry, San Diego, CA, March 1994.) Funded by ACERC and the Consortium for Fossil Fuel Liquefaction (US Department of Energy).

Less than two decades ago a typical mass spectrometer was an extremely expensive and delicate instrument that would completely take up a moderately sized laboratory room. Few coal scientists or engineers had access to such an instrument and even fewer mass spectrometrists were willing to "contaminate" their instrument with something as complex and dirty as coal and its tar. Against this historic background it is nothing less than amazing that as early as 1966 Vastola et al. at Penn State University, using a finely focused ruby laser and a time of flight (TOF) mass spectrometer, already carried out laser pyrolysis experiments on coal samples inside the ion source. Joy et al soon followed their example. However, since Vastola's experiment was too far ahead of the state-of-the-art in signal processing electronics it would take more than 15 years before his group was able to obtain reproducible pyrolysis mass spectrometry (Py-MS) patterns from a series of PSOC coal samples.

In the meantime, the same coal samples had already been studied by Curie-point pyrolysis mass spectrometry (Py-MS) in our own laboratory as part of a series of 104 Rocky Mountain Province coals. The latter study demonstrated the reproducibility of carefully designed, dedicated Py-MS instruments, as well as the power of multivariate statistical analysis techniques, for reducing the voluminous MS data and bringing out the most significant chemical components and trends.

Already during the late seventies and early eighties several organic geochemistry groups, e.g., at the Technical University Delft at Chevron and at the University of Bartlesville had started to use pyrolysis-gas chromatography/mass spectrometry to characterize a broad range of different coals and coal macerals. Yet another promising instrumental approach, namely thermogravimetry (TG) in direct combination with MS was being developed further by Szekely's laboratory in Budapest followed by the development of a vacuum TG/MS system in our own laboratory. In the mid eighties further advances in TG/MS techniques were reported by Ohrbach and Kettrup using a commercially available molecular beam type interface. Most recently, a homebuilt TG/MS system based on similar principles was successfully tested in our own laboratory. Finally, the promising results of the various TG/MS combinations prompted us to pursue more sophisticated analytical configurations such as TG/IR/MS and TG/GC/MS, with the latter method eventually being adapted to on-line analysis of high pressure reactions, as reported by Kui et al.

In the mid eighties, Schulten's laboratory in West Germany started pursuing an entirely different approach involving direct probe type pyrolysis of coal directly in the ion source of a high resolution magnetic sector MS system with field ionization (FI) and field desorption (FD) capabilities. Related FIMS work was reported at SRI by Malhotra et al. That a wealth of information on coal conversion processes and reaction products could also be obtained by high resolution MS in combination with other ionization methods, such as low voltage electron ionization (LVEI) and fast atom bombardment (FAB) was elegantly demonstrated by Winans et al. at Argonne National Laboratory. Last year, a collaborative comparison between different desorption/ionization methods capable of producing ion signals up to several thousand Dalton was performed by two different research groups. Barely was their report submitted or one of the authors published several articles raising the upper mas limit of detected ion species to 4,000 and 270,000 Dalton for FAB and matrix assisted laser desorption/ionization, respectively.

Obviously, high mass MS techniques are presently a hot topic in coal science. However, in order to keep the scope of this article within the limitations posed by the ACS Fuel Chemistry Division preprint format, only techniques and applications of MS methods involving direct coupling to micro-scale or upscale coal conversion reactors will be discussed.

Field Portable Hyphenated Instrumentation: The Birth of the Tri-Corder?

McClennen, W.H.; Arnold, N.S. and Meuzelaar, H.L.C.
Trends in Analytical Chemistry, 13(7):286-293, 1994. Funded by Hewlett Packard and US Army.

The "tricorder," the tiny universal sensor of "Star Trek" science fiction fame, might be the ultimate objective for developers of field-portable instrumentation. The advantages of multi-dimensional ("hyphenated") analytical methods over one-dimensional techniques in working toward such a goal are based upon the degree of correlation of the information from the combined analytical techniques. With appropriately selected techniques that yield complementary (orthogonal) information, the actual resolution of the hyphenated technique is the product of the resolution of the two techniques. In effect, the whole of a suitable hyphenated system is greater than the sum of its parts.

The most widely used hyphenated method, combined gas chromatography-mass spectrometry (GC-MS), is regarded as the definitive method for certain applications and has become the officially required procedure for numerous environmental, clinical and occupational health or safety related tests. In fact, in most laboratories GC-MS has all but replaced the use of one-dimensional GC and MS techniques. Consequently, results based on characterization of complex environmental samples by GC or MS alone would tend to be disregarded or seen as tentative, at best. Yet, the use of one-dimensional GC and MS techniques represents the present state-of-the-art in field screening methods. The demonstration of hyphenated analytical techniques in field application via the use of mobile laboratories has been established in the last 10 years by a number of researchers using MS-MS or GC-MS techniques. However, it is appropriate to consider whether a field laboratory constitutes a truly field-portable analytical technique.

In-situ applications are an area of field portability where the use of hyphenated methods is a recent phenomenon that can be expected to continue due to the considerable power of these approaches. However, the large-scale acceptance of these techniques in the field will depend upon overcoming the constraints of inherent higher cost, complexity, size, weight and power requirements.

On the other hand, hyphenated techniques should certainly not be seen as a panacea for every analytical problem, whether in the laboratory or in the field. Although the information provided by a multi-dimensional method is often much greater than the summed information obtainable from the component techniques, a poorly designed hyphenated experiment may end up amplifying the characteristic weaknesses and shortcomings of the component methods and provide little or no useful information. In effect, the use of sophisticated hyphenated methods is certainly not a satisfactory way to compensate for a poor analytical technique!

Performance Advances in Ion Mobility Spectrometry by Combination with High-Speed Vapor Sampling, Preconcentration, and Separation Techniques

Dworzanski, J.P.; Kim, M.-G.; Snyder, A.P.; Arnold, N.S. and Meuzelaar, H.L.C.
Anal. Chimica Acta, 293:219-235, 1994. Funded by US Army Chemical Research Development and Engineering Center and Battelle.

Rugged, low weight, hand-held ion mobility spectrometry devices, initially developed for chemical warfare detection purposes, possess attractive characteristics as field-portable instruments for paramilitary (treaty verification, chemical demilitarization, drug interdiction, counterterrorism operations) and civilian (environmental monitoring, forensic characterization, process control) applications. Generally, however, such devices tend to exhibit limited resolution, narrow dynamic range, nonlinear response and long clearance times which severely limit their usefulness for qualitative and quantitative analysis of mixtures. To overcome these restrictions a prototype combined gas chromatography/ion mobility spectrometry (GC/IMS) unit was constructed by replacing the membrane inlet of a military IMS device known as the CAM (Chemical Agent Monitor) with suitable front-end modules. These modules enable high speed automated vapor sampling (AVS), microvolume preconcentration/thermal desorption, and isothermal GC preseparation of analytes using a short capillary column while operating the IMS source and cell at subambient pressures as low as 0.5 atm. The AVS-GC/IMS methodology sharply reduces competitive ionization and facilitates identification of mixture components, thereby enabling quantification of volatile and semivolatile compounds over a broad range of concentrations in air. At higher concentral levels (e.g.>1 ppm) using the AVS inlet in automatic attenuation control (AAC) mode maintains excellent linear response. At ultralow concentration levels, e.g. < 10 ppb, a microvolume, trap-and-desorb type preconcentration module, maintains adequate signal to noise levels, thereby expanding the effective dynamic range of the method to appox. 6 orders to magnitude (100 pp 5-100 ppm). The resulting "hyphenated" GC/IMS technique has the potential of evolving into the first hand-portable combined chromatography/spectroscopy instruments for field screening applications.

1993

Development of a Laser Devolatilization Gas Chromatography/Mass Spectrometry Technique for Single Coal Particles

Maswadeh, W.; Arnold, N.S.; McClennen, W.H.; Tripathi, A.; DuBow, J. and Meuzelaar, H.L.C.
Energy & Fuels, 7 (6):1006-1012, 1993. Funded by ACERC.

A CO2 laser Py-GC/MS system capable of identifying substantial numbers of pyrolysis products from single coal particles in the 50-15-µm range is reported. Also, a specially designed two-wavelength radiation thermometer module with integral video microscope produces reliable temperature/time profiles of single coal particles during rapid laser heating. A novel microbeam footprint technique using thin quartz wafers in combination with videomicroscopy greatly facilitates laser beam focusing and alignment operations. Comparison of an EDB type particle levitator with an EM grid type particle support system reveals considerable advantages of the EM grid approach with regard to tar collection efficiency, particle position stability, particle visualization, and recoverability of residual char particles. However, possible cooling effects of the grid on highly thermoplastic particles require further study. The feasibility of simulating PCC conditions with regard to heating rates and final particle temperatures is demonstrated with complete devolatilization of 100 µm diameter particle being observed within 10 ms. The nature and relative abundance of major pyrolysis products observed at typical laser heating rates (>=105 K/s) are found to be closely similar to those observed with Curie-point pyrolysis techniques at heating rates in the 10²-10³ K/s range. Spherocarb particles of approximately 102-µm diameter, e.g., impregnated with suitable coal tar compounds are shown to provide useful model samples for system optimization and calibration purposes.

High Speed, Two-Wavelength Radiation Thermometry of Single Micro Particles During CO2 Laser Heating

Maswadeh, W.; Tripathi, A.; Arnold, N.S.; DuBow, J. and Meuzelaar, H.L.C.
Journal of Analytical and Appl. Pyrolysis, 1993 (in press). Funded by ACERC.

A high speed, two-wavelength radiation thermometer that is capable of monitoring the surface temperature of 50-150 µm diameter particles in the 600-2000 K range at heating rates of up to 106 K/s, characteristic of pulverized coal combustion, was designed and constructed. To meet the above characteristics, special attention was paid to detector wavelength range and speed, detection electronics and optical system alignment. The thermometer was calibrated using an in-house constructed, black cavity radiation source. Spherocarb model particles, which have a more uniform size; physical properties and emissivity than coal particles, were used to demonstrate the level of short-term reproducibility attainable. Consistent, reproducible temperature-time profiles obtained for particles from different coals indicate that non-grey effects do not dominate these measurements.

The Effect of the Mobile Component on the Liquefaction Characteristic of Western Kentucky Coals

Keogh, R.A.; Hardy, R.H.; Taghizadeh, K.; Meuzelaar, H.L.C. and Davis, B.H.
Fuel Processing Technology, 1993 (in press). Funded by US Department of Energy.

The mobile component of western Kentucky coals were extracted and analyzed by conventional methods and Curie-point mass spectroscopy. The liquefaction of the parent coals, extracted coals, and blends of the extracted coals plus mobile components indicated that the absence of the mobile component generally decreases the observed conversions obtained. The results also show that, in general, blending the mobile component and extracted coal also produces lower conversions than those obtained from the parent coal. These data suggest that the location of the mobile component in the pore structure of the coal is as important as the presence of the mobile component in coal conversion.

Role of On-Line Mass Spectrometry for Studying the Structure/Reactivity Relationships and Conversion Processes of Coal

Meuzelaar, H.L.C.
Proceedings of American Chemical Society Conference Fuel Division, ACS Preprints, Fuel Chem. Div., 1993 (in press). Funded by ACERC.

Less than two decades ago a typical mass spectrometer was an extremely expensive and delicate instrument that would completely take up a moderately sized laboratory room. Few coal scientists or engineers had access to such an instrument and even fewer mass spectrometrists were willing to "contaminate" their instrument with something as complex and dirty as coal and its tar. Against this historic background it is nothing less than amazing that as early as 1966 Vastola et al. at Penn State University, using a finely focused ruby laser and a time of flight (TOF) mass spectrometer, already carried out laser pyrolysis experiments on coal samples inside the ion source. Joy et al soon followed their example. However, since Vastola's experiment was too far ahead of the state-of-the-art in signal processing electronics it would take more than 15 years before his group was able to obtain reproducible pyrolysis mass spectrometry (Py-MS) patterns from a series of PSOC coal samples.

Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques

Nie, X.; Lui, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
Proceedings ACS Conference Fuel Chem. Division, ACS Preprints, Fuel Chem. Div., 1993 (in press). Funded by ACERC.

During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure. The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.

Microscale Simulation of High Pressure Thermal and Catalytic Conversion Processes in Coal and Waste Polymers with On-Line GC/MS

Liu, K.; Jakab, E.; McClennen, W.H. and Meuzelaar, H.L.C.
Proceedings of the 206th American Chemical Society National Meeting, ACS Preprints, Fuel Chem. Div., 38 (3): 823-830, Chicago, IL, August 1993. Funded by US Department of Energy.

Over 279 million automotive tires are discarded in the United States each year. These used tires cause serious environmental problems since they are non-biodegradable, occupy considerable landfill space, and emit noxious fumes when burned. One of the promising approaches to deal with used rubber is the co-processing of it with coal to produce hydrocarbon liquids for use as fuels and specialty chemicals. Recently there have been numerous studies on co-processing of tire rubber and coal since depolymerized rubber has good solvent properties and the carbon black which constitutes of about 20-30% of the rubber is a good catalyst for depolymerization and possibly enhanced coal liquefaction. Monitoring sample weight loss as a function of temperature with on-line analysis of the evolved products during the co-processing reactions is necessary to elucidate mechanisms and kinetics of the key conversion reactions. Due to the high pressure and high temperature required by some of the most interesting processes, it is difficult to continuously monitor the weight loss and reaction intermediates without interrupting the reactions.

On-line analysis techniques for high-pressure conversion reactions have been reported previously, but these systems did not monitor total weight loss vs reaction temperature. They also were not applied directly to coal conversion studies because of the strong potential for plugging of sample orifices with pulverized coal. Microscale simulation of coal conversion reactions has been performed by high-pressure thermogravimetry with on-line combined gas chromatography and mass spectrometry (TG/GC/MS). It requires only a small sample size and can be operated at high temperature and pressure. The weight loss and low molecular weight products can be monitored vs reaction temperature. Analysis of pyrolysis and hydropyrolysis of coal, rubber and coal with tire rubber, with our without catalyst, by high pressure TG/GC/MS are reported here.

Development of On-Line GC/MS Monitoring Techniques for High-Pressure Fuel Conversion Processes

Nie, X.; McClennen, W.H.; Liu, K. and Meuzelaar, H.L.C.
Proceedings of the 206th American Chemical Society National Meeting, ACS Preprints, Fuel Chem. Div., 38 (4), Chicago, IL, August 1993. Funded by US Department of Energy.

It is well known that on-line analytical methods offer considerable advantages over conventional off-line procedures for fuel conversion processes. Although many on-line spectroscopic detection systems for thermal process reactors have been reported, they have had only very little application to high-pressure reactors. Therefore, relatively little is known about the precise pathways and intermediate products involved in high-pressure reactions. The application of real time, on-line chromatographic and/or spectroscopic techniques capable of throwing light on these processes is hampered by the high temperatures and pressures inside the reactor which complicate direct interfacing to standard analytical instruments.

Thermogravimetry (TG) can provide detailed information on thermally driven conversion reactions, especially when combined with on-line detection and identification techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). However, high pressure TG systems have only recently become available for studying the basic pyrolysis and especially hydropyrolysis reactions involved in coal liquefaction, thus, the combined chromatographic/spectroscopic interfaces for such high pressure systems are only now producing results. Other high-pressure reactors of interest include those used to study the thermal processes in liquid fuels or in solvent-based coal conversion. Thus there have been recent reports of on-line GC/MS monitoring of a high pressure recirculating autoclave used to study coal derived liquid model compounds. Other work in our laboratory has examined the supercritical pyrolytic degradation of jet fuels with on-line GC/IR/MS. Several of these systems have involved the use of a patented automated vapor sampling (AVS) inlet with short column or so-called "transfer line" gas chromatography (TLGC) with MS or FTIR.

This paper presents the experimental descriptions and results from three high-pressure systems using a variety of components. The first is a high pressure TG/GC/MS system used to study coal hydropyrolysis. The other two use quartz-tubing reactors to examine the liquid and gaseous products from the thermal decomposition of jet fuels.

Mass Determination of Trapped Micro-Particles and Macro-Ions by Optical Techniques (and Subsequent Chemical Analysis by Laser Pyrolysis Mass Spectrometry)

Hars, G.; Arnold, N.S. and Meuzelaar H.L.C.
Proceedings of the 41st ASMS Conference on Mass Spectrometry and Allied Topics, San Francisco, CA, May 1993. Funded by US Army Research Office.

Extensive analytical interest in characterization of particulate matter extends in many applications to evaluation of individual micro-particles. For complete chemical characterization of individual microparticles adequate measurements of both particle physical characteristics (e.g., size, mass) and chemical constituents are required. Like molecular species, particles may also be readily ionized and manipulated by electrical techniques based on mass to charge ratios. An approach favored by the authors would provide an accurate mass determination that could be followed by laser pyrolysis (ionization) mass spectrometry to determine the chemical composition. Both measurements can be carried out in the same ion trap but they require different electrical operating conditions. For particle mass determination the ion trap operates as an Electrodynamic Balance (EDB) while the compositional analysis is performed in the Ion Trap Mass Spectrometer (ITMS) mode. For macro-ions and submicron particles the distinction between ions and charged particles may become blurred making it profitable to consider the ability to make mass measurements of individual submicroparticles based on optical detection techniques.

On-Line Monitoring of Formaldehyde in Combustion Gases Using Gas Chromatography/Mass Spectrometry

McClennen, W.H.; Sheya, S.A.N.; Arnold, N.S.; Meuzelaar, H.L.C.; Larsen, F.S. and Silcox, G.D.
Incineration of Hazardous Wastes-2; Toxic Combustion By-Products:545-555, (in press). Funded by Consortium for Fossil Fuel Liquefaction and ACERC.

This paper describes a method for on-line gas chromatography/mass spectrometry (GC/MS) of formaldehyde in combustion gases. The method uses a recently developed vapor-sampling inlet to monitor the concentration of formaldehyde and other products of incomplete combustion (PICs) from the burning of plain and phenol-formaldehyde resin treated wood chips. Other PICs that were simultaneously monitored included ketene, propylene, propyne and acetaldehyde. The direct analysis method has detection limits of less than 1 ppm for the reactive formaldehyde and excellent selectivity for determinations in the complex mixtures of combustion products. The rapid sampling technique allows monitoring of transient events of only a few minutes or less duration. Examples of the technique include the detection of sample line problems and the comparison of PIC concentrations from different points in the combustion exhaust stream.

Novel Automated Chromatographic and Spectroscopic Techniques for On-Line Combustion By-Product Monitoring

Meuzelaar, H.L.C.; McClennen, W.H.; Arnold, N.S.; Dworzanski, J.P. and Kim, M.-G.
Incineration of Hazardous Wastes-2; Toxic Combustion By Products: 513-530, (in press). Funded by Consortium for Fossil Fuel Liquefaction and ACERC.

A new generation of on-line combustion product and by-product monitoring techniques based on the combination of a novel, automated vapor sampling (AVS) concept with so-called "transfer line gas chromatography" (TLGC) and any of several possible spectroscopic techniques is described. The automated vapor sampling method is characterized by the exclusive presence of quartz glass surfaces in the path of sample molecules between sampling point and detector, as well as by very short vapor sampling times (typically ˜ 1 sec), thereby facilitating rapid chromatographic separation using a short length (e.g., 1-6 ft) of fused silica capillary GC column. Laboratory test data are provided for three different instrumental configurations, namely AVS-TLGC in combination with: (1) mass spectrometry (MS); (2) MS and Fourier transform infrared spectroscopy (FTIR); and (3) ion mobility spectrometry (IMS).

Whereas on-line GC/MS monitoring is clearly the preferred approach when maximum specificity and sensitivity are required, GC/IR has important advantages for monitoring gaseous combustion products and distinguishing isomeric species and on-line GC/IMS appears to offer a sensitive, relatively inexpensive and simple monitoring tool for selected target compounds.

Portable Hand-Held Gas Chromatography/Ion Mobility Spectrometry Device

Snyder, A.P.; Harden, C.S.; Brittain, A.H.; Kim, M.-G.; Arnold, N.S. and Meuzelaar, H.L.C.
Analytical Chemistry, 65:299-306, 1993. Funded by US Army and University of Utah.

The concept of a portable gas chromatography/Ion mobility spectrometry (GC/IMS) device is introduced. The potential of the GC/IMS unit is investigated for the separation and characterization of vapor mixtures of various chemical classes. Parameters such as internal cell pressure, GC column flow rate, and column temperature were varied to determine the effects on speed and resolution for separating and characterizing mixtures. It was generally found that by reducing both the internal IMS cell pressure and the isothermal GC column temperature, the peak widths, retention times, and peak overlap could be varied for different classes of analytes. The GC/IMS system shows versatility in the various compound classes that can conveniently be analyzed by a hand-portable version. Mixtures included phosphonates, phosphates, alkyl ketones, and chlorophenois with total separation times in the 7-s to 2-min time range. Positive or negative ion polarities in IMS were used depending upon the functional group.

Performance Advances in Ion Mobility Spectrometry through Combination with High-Speed Vapor Sampling, Preconcentration and Separation Techniques

Dworzanski, J.P.; Kim, M.-G.; Snyder, A.P.; Arnold, N.S. and Meuzelaar, H.L.C.
Anal. Chimica Acta, 1993 (in press). Funded by Chemical Research Development and Engineering Center and Battelle.

Rugged, low weight, hand-held ion mobility spectrometry devices, initially developed for chemical warfare detection purposes, possess attractive characteristics as field-portable instruments for paramilitary (treaty verification, chemical demilitarization, drug interdiction, counterterrorism operations) and civilian (environmental monitoring, forensic characterization, process control) applications. Generally, however, such devices tend to exhibit limited resolution, narrow dynamic range, nonlinear response and long clearance times which severely limit their usefulness for qualitative and quantitative analysis of mixtures. To overcome these restrictions a prototype combined gas chromatography/ion mobility spectrometry (GC/IMS) unit was constructed by replacing the membrane inlet of a military IMS device known as the CAM (Chemical Agent Monitor) with suitable front-end modules. These modules enable high speed automated vapor sampling (AVS), microvolume preconcentration/thermal desorption, and isothermal GC preseparation of analytes using a short capillary column while operating the IMS source and cell at subambient pressures as low as 0.5 atm. The AVS-GC/IMS methodology sharply reduces competitive ionization and facilitates identification of mixture components, thereby enabling quantitative of volatile and semivolatile compounds over a broad range of concentrations in air. At higher concentral levels (e.g.>1 ppm) using the AVS inlet in automatic attenuation control (AAC) mode maintains excellent linear response. At ultralow concentration levels, e.g. < 10 ppb, a microvolume, trap-and-desorb type preconcentration module, maintains adequate signal to noise levels, thereby expanding the effective dynamic range of the method to appox. 6 orders to magnitude (100 pp 5-100 ppm). The resulting "hyphenated" GC/IMS technique has the potential of evolving into the first hand-portable combined chromatography/spectroscopy instruments for field screening applications.

Thermogravimetry/Gas Chromatography/Mass Spectrometry and Thermogravimetry/Gas Chromatography/Fourier Transform Infrared Spectroscopy: Novel Hyphenated Methods in Thermal Analysis

McClennen, W.H.; Buchanan, R.M.; Arnold, N.S.; Dworzanski J.P. and Meuzelaar, H.L.C.
Analytical Chemistry, 65:2819-1823, 1993. Funded by Hewlett Packard and ACERC.

Two doubly hyphenated, thermogravimetry-based analytical techniques, viz. TG/GC/MS and TG/GC/IR, are described. A valveless, quartz, heated sample path between TG furnace and GC column minimizes losses of products. Furthermore, combination of a pulsed automated vapor-sampling inlet and a transfer line type GC column permits high-speed GC identification of individual TG products while maintaining sufficiently high temporal resolution with the ~1-min sampling interval to provide kinetic information about the underlying reaction mechanisms. Example analyses on poly (alpha-methylstyrene), a styrene-isoprene block copolymer, and wood demonstrate the techniques' capability for monitoring specific minor products and isomers.

Interfacting High-Speen Transfer Line Gas Chromatography to Ion Trap Mass Spectrometry; Advantages and Limitations

Arnold, N.S.; McClennen, W.H. and Meuzelaar, H.L.C.
Proceedings of the 41st ASMS Conference on Mass Spectrometry and Allied Topics, San Francisco, CA, June 1993. Funded by US Army/Electrical Research Development and Engineering Center and ACERC.

The Ion Trap Detector (ITD, Finnigan-MAT) was originally introduced as a gas chromatography (GC) detector for laboratory bench top GC/MS analyses. Its introduction coincided with a rising interest in a vacuum outlet short column GC/MS for high-speed chromatographic separations. Advantages for such short column applications, including high operating pressures (10-3 torr) sensitivities (.1 fg/s) and scan speeds (5500 amu/s) relative to conventional quadruple instruments, have fueled interest in ion trap based instruments for high speed, high resolution GC/MS analyses. Subsequent interest has been fueled by new developments in mobile instruments, high sensitivity MSn capability, AGC-based dynamic range enhancement, and axial modulation based resolution enhancement.

The Next Step in Miniaturization Toward Personal GC/IMS

Arnold, N.S.; Dworzanski, J.P.; Meuzelaar, H.L.C. and McClennen, W.H.
Proceedings of US Army Electrical Research Development and Engineering Center Science Conference on Chemical Defense Research, Aberdeen, MD, November 1993. Funded by US Air Force.

Field portable gas chromotography/ion mobility spectrometry (GC/IMS) techniques have been identified as an important area of development for CW detection. Recent developments of smaller, personal IMS detection devices offer new prospects for miniaturization of a combined personal GC/IMS unit that would have considerable size and cost advantages over its larger predecessors. The following is a preliminary examination of feasibility of personal GC/IMS based on an automated vapor sampling-transfer line gas chromatography (AVS-TLGC) approach previously used in developing hand portable GC/IMS instrumentation. Special focus is placed upon developing low power GC interfacing strategies for an existing prototype miniature IMS device. Parameters such as GC column position and flow as well as IMS purge flows are examined for their effects on sensitivity and resolution.

Portable, Handheld Instrumentation: Gas Chromatography/Ion Mobility Spectrometer

Snyder, A.P.; Harden, C.S.; Brittain, A.H.; Kim, M.-G.; Arnold, N.S. and Meuzelaar, H.L.C.
Proceedings of the International Symposium on Field Screening Methods for Hazardous Waste and Toxic Chemicals: 831-841, Las Vegas, NV 1993. Funded by US Army and University of Utah.

The concept of a one hand-portable gas chromatography/ion mobility spectrometry (GC/IMS) device is introduced. The potential of the GC/IMS unit is investigated for the separation and characterization of vapor mixtures of various chemical classes. The column temperature was varied to determine the effects on speed and resolution for separating and characterizing mixtures. The GC/IMS system shows versatility in the various compound classes that can conveniently be analyzed by a hand-portable version. Mixtures included amines, alcohols and drug synthesis/purification solvents with total separation times in the 7-30 sec time range, and all were analyzed in the positive ion mode.

Chemical Characterization of Single Aerosol Particles Via Combined Electrodynamic Balance/Ion Trap Mass Spectrometry Techniques

Hars, G.; Arnold, N.S., Meuzelaar, H.L.C.
Proceedings of American Chemical Society Meeting, Chicago, IL, August 1993. Funded by US Army Research Office.

A multifunction Paul trap is described capable of trapping, stabilizing and analyzing electrostatically charged microparticles as well as a broad range of ions and macro-ions. Typically, particles in the 0.1-10 µm range are introduced by aerosolization from an aqueous suspension, although quasi-electrospray and dry powder type introduction methods can also be used. A new particle trajectory pattern, observed in the equatorial plane, was found to offer a nondestructive, optical method for determining the m/z value of microparticles and macro-ions, with a present accuracy of 1:103 and a potential maximum resolution of 1:106. Recent addition of a more powerful laser (Nd YAG, operating at 1.06 µm) has enabled us to generate laser fragmentation/ionization mass spectra of 1 µm dia polystyrene particles and of Bacillus subtilis spores. Current shot-to-shot reproducibility is still unsatisfactory and some as yet unresolved, mass calibration problems have been encountered. Nonetheless, the high intensity and apparent complex organic nature of the ion signals obtained might herald the emergence of a novel MS technique for chemical and physical characterization of single microorganisms and other components of respirable aerosols.

Performance Advances in Combined Gas Chromatography/Ion Mobility Spectrometry through High-Speed Vapor Sampling, Preconcentration, and Pyrolysis Techniques

Dworzanski, J.P.; Meuzelaar, H.L.C.; Arnold, N.S.; Kim, M.-G. and Snyder, A.P.
Proceedings of US Army Electrical Research Development and Engineering Center Science Conference on Chemical Defense Research, Aberdeen, MD, November 1993 (in press). Funded by US Department of Defense Electrical Research Development and Engineering Center and Battelle.

Detection and characterization of low volatile and nonvolatile organic matter as well as extension of the effective dynamic range of ion mobility spectrometry (IMS) for analysis of volatile organic compounds are achieved by interfacing handheld IMS units to special inlet modules. Modules consist of a high-speed adsorption/desorption or pyrolysis unit (Curie-point heating technique) coupled to an automated vapor sampling (AVS) inlet and a short (2-3m), isothermal GC column. The AVS-GC/IMS methodology allows quantitation of compounds over a broad range of concentrations (i.e., 10 ppb - 100 ppm) in air through a computer-controlled, variable sampling time technique. Minimum detectable concentrations can be further reduced (e.g., to 90 ppt) by means of a microvolume, trap-and-desorb type preconcentration module, thereby expanding the effective dynamic range to approx. 6 orders of magnitude. Finally, when operating in pyrolysis mode the instrument can be used to obtain reproducible and characteristic GC/IMS pyrograms for a broad range of polymers.

The Next Horizon in Portable GC/MS for Field Air Monitoring Applications

Arnold, N.S.; Cole, P.A.; Hu, D.W.; Watteyne, B.; Urban, D.T. and Meuzelaar, H.L.C.
International Symposium on Field Screening Methods for Hazardous Wastes & Toxic Chemicals, Pittsburgh, PA, 2, 915-931, 1993. ( Also presented at 1993 International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1993 and presented at the 41st ASMS Conference on Mass Spectrom. All. Topics, San Francisco, CA, January 1993). Funded by Hewlett Packard and ACERC.

Over the past few years, GC/MS has struggled out of the laboratory and into field applications. In spite of its complexity and size limitations, the sheer analytical power of this hyphenated technique has helped it earn its place in the field. A number of workers have demonstrated "transportable" GC/MS systems that may be moved to a field site and operated via personnel bringing samples to the instrument or via long heated sample transfer lines. The next horizon is to bring truly field-portable equipment to the field analytical problem. This horizon can be reached via the so-called "man-portable" GC/MS systems that can be operated while moving with an individual and are thus capable of addressing problems in situ, rather than just on-site.

The requirements of such systems are stringent. We suggest that realistic goals include high speed GC separation, low ppb sensitivity, remote control capability for hazardous environments, 25 lbs total system weight and 60 W total system power consumption. To obtain these goals innovative low power pumping techniques, lightweight materials and small mass analyzers are an absolute necessity. The present paper discusses the engineering design specifications of an integrated man-portable GC/MS system. Trade-offs to obtain sufficient GC flow rates and operating pressures are considered together with weight and power consumption issues for various mass analyzer configurations. The available pumping technology and its ability to meet stringent power and weight requirements will also be considered.

An existing demonstration prototype system developed in our laboratory and utilizing an HP 5971A mass analyzer system, an automated vapor sampling "transfer line" GC interface and a novel bulk getter pumping system along with remote laptop computer operation will be used as a benchmark. This system has already broken through the 100 W barrier with an approx. 50 lbs weight while utilizing a trap-and-desorb approach to obtain ppb level sensitivities. It is already clear that this system can meet many of the analytical challenges posed, but some discussion will be presented of the remaining hurdles required to meet power and weight requirements.

Man-Portable GC/MS; Opportunities, Challenges, and Future Directions

Meuzelaar, H.L.C.
International Symposium Field Screening Methods for Hazardous Wastes and Toxic Chemicals, 1:35-54, Pittsburgh, PA, 1993. (also presented at the International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, June 1993. Funded by Hewlett Packard, US Department of Defense and ACERC.

Simultaneous advances in miniaturized mass spectrometry (MS) equipment and in field-portable gas chromatography (GC) devices have brought development of man portable GC/MS instruments within reach. Among the various levels of man portability, viz. "luggable," "wearable" or "hand-portable," the latter category is likely to remain an elusive target for GC/MS for the remainder of this millennium. Since hand-portables are unlikely to become feasible soon and "luggables" obviously leave much to be desired, "wearable" GC/MS systems would appear to constitute a logical development benchmark for the immediate future.

Our laboratory has described a wearable, GC/MS system for air monitoring applications based on the integration of a fully automated, repetitive air sampling inlet, a short isothermal capillary GC column, a low power quadruple mass filter (modified HP MSD), a hybrid (bulk getter/ion getter) vacuum system and a PC notebook computer. The system weights 60 lbs, consumes 90 W of battery power and should run 2-3 hrs on high-density disposable batteries. Other man portable GC/MS prototype systems scheduled for completion in the near future are under development at Jet Propulsion Laboratory and at Lawrence Livermore National Laboratory. Major remaining challenges include the need for: further weight reduction; 102-103 times higher sensitivity; and improved man/machine interfaces. Possible future directions are likely to include: drone-portables; use of neural network processors; and, eventually hand-portable GC/MS systems.

Development of Field-Portable Mass Spectrometric Techniques for Particulate Organic Matter in PM-10

Dworzanski, J.P.; Meuzelaar, H.L.C.; Maswadeh, W.; Nie, X.; Cole, P.A. and Arnold, N.S.
Proceedings of the International Symposium on Field Screenings Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1993. Funded by Southwest Center for Environmental Research and Policy, and the Environmental Protection Agency.

The chemical composition and structure of particulate organic matter can provide important information regarding origin, distribution and fate of respirable aerosols (PM-10) in the environment. Nevertheless, because of a lack of fast and reliable methods for chemical characterization of the organic components of the PM-10 fraction, most source apportionment studies focus exclusively on specification of inorganic components. In view of its inherent sensitivity, specificity and quantitative response, mass spectrometry (MS) offers obvious promise for characterization of the organic fraction. Consequently, special collection and sampling modules suitable for MS analysis of PM-10 have been developed in our laboratory and field-tested. The modules consist of a sampling unit and a low-dead volume Curie-point thermal desorption/pyrolysis inlet interfaced to a temperature programmable "transfer line" capillary column which is coupled to a ruggedized, miniaturized Finnigan MAT ion trap mass spectrometer (ITMS).

From among the PM-10 collection methods for MS investigated in our laboratory quartz fiber filters were selected because of inherent simplicity and high collection efficiency. After PM-10 collection, quartz filters underwent thermal desorption or pyrolysis followed by on-line GC/MS analysis. This approach was used to characterize the organic matter in particulate samples collected at 3-hour intervals at the US/Mexican border. Subsequent principal component analysis of selected mass profiles together with particle density and size distribution data as well as meteorological parameters allowed tentative identification of several PM-10 sources, including automotive emissions, food preparation and wood burning.

1992

Computer-Enhanced Pyrolysis Mass Spectrometry; A New Window on Coal Structure and Reactivity

Yun, Y.; Meuzelaar, H.L.C.; Chakravarty, T.; and Metcalf, G.S.
Chapter 12, Advances in Coal Sprectroscopy, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1992. [Previously published in Computer Enhanced Analytical Spectroscopy, Volume II, (Meuzelaar, H.L.C., ed.), Plenum Publishing Corp., New York, 1990]. Funded by Pittsburgh Energy Technology Center/CFFLS and ACERC.

Coals may be regarded as highly complex, fossilized assemblages of more or less strongly decomposed plant matter, microorganisms and humic substances in addition to a range of possible mineral constituents. Specific coal seams may represent peat-forming palaeoenvironments as diverse as river delta swamps, salt-water marshes or rain forest bogs, thus explaining the intrinsic heterogeneity of coal at the macroscopic as well as microscopic levels. Macroscopically, coal heterogeneity is often readily visible in the form of discrete bands representing successions of different depositional environments or, perhaps, catastrophic events such as floods and forest fires. At the microscopic level most coals display an even broader scale of diversity and heterogeneity in the form of microscopically distinct coal components generally referred to as "macerals."

Advances in Coal Spectroscopy

Meuzelaar, H.L.C.; Schrenk, W.G.; Grove, E.L.; Frei, R.W.; Lawrence, J.F.; Isenhour, T.L.; Small, H.; Freiser, H.; Yergey, A.L.; Edmonds, C.G.; Lewis, I.A.S.; Vestal, M.L.; Wehry, E.L.; Carlson, T.A.; Janata, J. and Griffiths, P.R.
(H.L.C. Meuzelaar, ed.) Plenum Publishing Corp., New York, 1992. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction and ACERC.

In order to promote and increased level of interaction and collaboration between coal spectroscopists, as well as to create an updated record of the current state of the art in this very active field, a three-day Symposium on Advances in Coal Spectroscopy was organized from June 14-16, 1989 at the Snowbird Mountain Resort in Utah. This book contains the keynote lectures presented by a group of preeminent coal spectroscopists involved in a broad range of different techniques and applications thought to represent current trends and developments in the field. Of necessity, the coverage of the field is far from comprehensive and in many ways the topics selected do reflect the personal preference and biases of the editor.

The fifteen chapters of this book focus on novel characterization methods (with special emphasis on sulfur forms), in situ microspectroscopic procedures, on-line process analysis methods, and computerized data analysis techniques.

C-13 NMR Techniques for Structural Studies of Coals and Coal Chars

Orendt, A.M.; Solum, M.S.; Sethi, N.K.; Pugmire, R.J. and Grant, D.M.
Chapter 10, Advances in Coal Spectroscopy, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1992. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, US Department of Energy and ACERC.

Techniques in C-13 nuclear magnetic resonance spectroscopy applied in the study of coal and coal chars are discussed along with details of the analysis of the spectral results. The results are compared for various methods of analysis: cross polarization with magic angle spinning (CP/MAS), dipolar dephasing (DD), MAS with block decays (BD), and chemical shielding anisotropy (CSA) measurements. Results of the CP/MAS and DD experiments on the Argonne premium coals as well as other coals and coal chars are reported in terms of twelve structural parameters, including aromaticity. Methods used to determine average cluster size and molecular weight are discussed. Models of coal structure and devolatilization processes are presented along with an analysis of the information obtained from the C-13 NMR experiments.

Thermochemical Analysis of US Argonne Premium Coal Samples by Time-Resolved Pyrolysis Field Ionization Mass Spectrometry

Simmleit, N.; Yun, Y.; Meuzelaar, H.L.C. and Schulten, H.R.
Chapter 13, Advances in Coal Spectroscopy, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1992. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, US Department of Energy and ACERC.

Analytical pyrolysis techniques are widely used for the thermochemical analysis of coals and coal-derived products. During heating, complex mixtures of chemical substances are released from coal by distillation, desorption and thermal degradation processes. The amount and chemical nature of the volatilized coal products are dependent mainly on the composition and structure of the coal and on heating conditions. Therefore, the results of chemical analyses of the volatilized coal products should provide information on the original structure of coal. For detailed on-line analysis of volatilized coal products usually chromatographic and/or spectroscopic methods have been used. For positive identification of compounds gas chromatography/mass spectrometry (GC/MS) is a common approach, e.g. in direct combination with pyrolysis techniques. However, due to the relatively long analysis times, in particular for high molecular weight products, GC/MS is not suited for a universal on-line monitoring of evolving coal products during heating. For rapid fingerprinting of volatilized coal products on a molecular basis direct MS analysis is often the preferred method. Small amounts of coal or coal-derived products are heated in front of th ionization region under high vacuum conditions. Depending on the type of mass spectrometer used and the experimental conditions, on-line monitoring of evolving coal products is possible for a wide range of heating rate. Heating rates as low as 10-2 C/s may be used in the combined thermogravimetry (TG)/MS whereas heating rates in the 104 - 106 C/s range can be obtained by CO2 laser heating.

Determining Molecular Weight Distributions of Polar Coal Derived Liquids by Means of Combined GC/MS and Vacuum TG Techniques

Huai, H. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(1):424-431, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction and ACERC.

A novel, low temperature (<300 C) coal liquefaction method described by Shabtai et al., consisting of a mild hydrotreatment (HT) step followed by base-catalyzed depolymerization (BCD) is thought to proceed by selective scission of C-C and C-O type bonds in the bridges connecting the aromatic and hydroaromatic clusters making up the bulk of the coal matrix, while minimizing secondary condensation reactions. Consequently, the resulting liquid products are expected to consist primarily of "monomeric" building blocks of the type and size inferred from solid state NMR measurements, i.e., corresponding to (hydro)aromatic structures with 10-15 aromatic carbons, 2-3 aliphatic carbons and 1-2 substituted oxygens (in addition to more sporadic sulfur, nitrogen or metal substituents) depending on coal rank, maceral composition, depositional environment and weathering status. In agreement with these expectations, the cyclohexane soluble "oil" fractions of the HT-BCD product, comprising up to 70% of the daf coal, were found to be completely vacuum distillable and to contain significant quantities of volatile, low MW components when analyzed by combined gas chromatography/mass spectrometry (GC/MS).

In order to further verify the mechanistic assumptions underlying the HT-BCD method as well as to obtain valuable information regarding type and size of the monomeric building blocks in coals, we decided to determine the precise molecular weight distribution (MWD) of HT-BCD oil fractions. The term MWD will be used interchangeably here with MMD (molecular or molar mass distribution). In view of the relatively low molecular weight and high polarity of the HT-BCD oil fractions, the use of gel permeation chromatography (GPC), also referred to as size exclusion chromatography, techniques was rejected in favor of mass spectrometry (MS) using "soft ionization" methods, such as field ionization (FI) and chemical ionization (CI), which tend to produce little or no fragmentation of molecular ions. Direct probe FIMS measurements were performed by Dr. H.R. Schulten (Fresenius Institute, Wiesbaden, GFR) whereas CIMS analyses were carried out in our laboratory using on-line preseparation by short column capillary gas chromatography (GC) and sample injection by means of Curie point flash evaporation. Well-known shortcomings of MS techniques include: possible loss of volatile components during sample introduction (in particular during direct probe MS); incomplete transport of low volatile components into the ion source (especially when using GC/MA); compound dependent response differences; and inability to analyze nonvolatile residues. Therefore, vacuum thermogravimetry (VTG) was selected as a tool for quantitative calibration, similar to its well-established use for calibrating simulated distillation (SIMDIS) methods. The results of these DP-FIS, GC/CIMS and VTG experiments with a mixture of coal liquid like model compounds as well as with HT-BCD oil fractions from three ANL-PCSP (Argonne National Laboratory - Premium Coal Sample Program) coals, viz. Beulah Zap lignite, Illinois #6 hvCb and Blind Canyon hvBb coals, will be reported here.

Structure/Reactivity Studies of Single Coal Particles at Very High Heating Rates by Laser Pyrolysis GC/MS

Maswadeh, W.; Fu, Y.; Dubow, J. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(1):699-706, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by ACERC.

Recently, Maswadeh et al. reported on the design, construction and testing of a single particle levitation/laser devolatilization apparatus featuring an on-line gas chromatograph/mass spectrometer (GC/MS) system, enabling coal devolatilization experiments of heating rates in the 10-5-106 K/s range. Analysis of bituminous coal particles revealed a high degree of qualitative correspondence with pyrolysis patterns obtained at much slower (10-2-100 K/s range) TG/MS heating rates, thus providing mechanistic justification for extrapolating kinetic parameters obtained by slow pyrolysis techniques (e.g., TG/MS and TG/IR) to the high heating rates characteristic of full scale, suspension fired coal combustors.

A second observation made with the aid of laser pyrolysis GC/MS was that the distribution of devolatilization products observed at very high heating rates was not measurably influenced by the presence or absence of air. A subsequent redesign of the system permitted the use of electron microscopy (EM) grids to support individual coal particles, thereby simplifying the experimental set up, improving collection efficiency of volatile products and facilitating optical alignment of the particles (microscopy, optical micropyrometry) as well as retrieval of residual char particles.

Development of a Single Chamber EDB/ITMS System for Laser Pyrolysis MS Analysis of Individual Microparticles

Arnold, N.S.; Hars, G.; Cole, P.A. and Meuzelaar, H.L.C.
US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense Research, Aberdeen Proving Ground, MD, November 1992. Funded by Army Research Office.

A novel technique for laser mass spectrometry of individual particles, e.g. microorganisms, is being developed. Present paper gives a detailed discussion on the theoretical and experimental aspects of trapping a submicron size charged particles pressures from atmospheric down to <10-7 torr. The ability to trap particles under UHV conditions has provided a new opportunity to study "ion trajectories" as they perform the solution of Mathieu equation.

Individual microparticles, mainly microorganisms, have been aerosolized and charged by a quasi-electrospray technique. A Paul type three-dimensional quadruple "trap" was constructed to combine the properties of an EDB (Electro-Dynamic Balance), capable of capturing the stabilizing micro-sized particles, with those of an ITMS (Ion Trap Mass Spectrometer), capable of trapping and mass selectivity detecting ionic species up to several thousand amu. A TEA CO2 laser (300 mJ per 200 µsec pulse) with focusing optics designed to produce a 50-80 µm beam waist through the center of the trap is used. A typical analysis cycle starts with the trap in EDB mode, thereby enabling capture and stabilization of one or more particles, followed by evacuation of the trap to high vacuum (<10-3 torr).

Portable, Hand-Held Gas Chromatography/Ion Mobility Spectrometer

Snyder, A.P.; Harden, C.S.; Brittain, A.H.; Kim, M.-G.; Arnold, N.S. and Meuzelaar, H.L.C
Analytical Chemistry, 1992 (in press). (Also included in American Laboratory, October:32B, 1992). Funded by US Army/Chemical Research Development and Engineering Center.

The general applicability of gas chromatography (GC) in combination with its reliability, to more complex chemical mixtures has made this technology particularly valuable in environmental and medical applications. Such monitoring are conducted in laboratory settings, in mobile field laboratories, and increasingly, in the field with hand-held portable analyzers. Hand-held systems have made significant technical gains in recent years to complement existing logistical attractions of coat and speed of analysis.

Ion mobility spectrometry (IMS) is an attractive technique in conjunction with GC for the determination of constituents in a mixture. The analyses of mixtures of amines, alcohols, and, in particular, the drug solvents performed in this study illustrate the effectiveness of IMS as a true additional dimension of detection for a GC system. Significant advantages to rapid screening, detection, and identification of both indoor and outdoor scenarios can be realized with the GC-IMS concept as a hand-held portable device.

Development of Microscale Reactors Directly Interfaced to GC/IR/MS Analytical System for High-Temperature Pyrolytic Degradation Studies of Jet Fuels in the Gas Phase or Under Supercritical Conditions

Dworzanski, J.P.; Chapman, J.; Meuzelaar, H.L.C. and Lander, H.R.
ACS National Meeting, San Francisco, CA, April 1992). Funded by Rocketdyne and ACERC.

Detailed knowledge of the thermal stability and pyrolytic degradation of jet fuels will play an important role in the design of advanced hypersonic (mach 5-8) aircraft systems making use of an endothermic reaction of the fuel prior to combustion (1). However, after decades of study fundamental processes leading to deposition of solid materials on fuel system components and thermal decomposition of fuels are not fully understood, largely due to the complexity of the processes involved which include fuel degradation chemistry, heat transfer and fluid mechanics.

Therefore, in our laboratory, new systems for pyrolytic degradation studies of jet fuels have been developed based on microscale laboratory reactors for the gas phase and liquid phase pyrolysis coupled directly to a doubly "hyphenated" analytical system consisting of a Hewlett-Packard has chromatograph/mass spectrometer/infrared spectrometer (GC/MS/IR) combination.

On-Line GC/MS Analysis of High Pressure Reactions

Dworzanski, J.P.; Huai, H.; Arnold, N.S. and Meuzelaar, H.L.C.
Proceedings of the Fortieth ASMS Conference on Mass Spectrometry and Allied Topics, 762-767, Washington, DC, 1992. Funded by Consortium for Fossil Fuel Liquefaction, Rocketdyne and ACERC.

The growing demand for real-time monitoring of industrial processes performed in reactors under conditions of high pressure and temperature indicates that MS technology, especially in combination with GC preseparation potential could fulfill many current requirements. To achieve these goals we have expanded the application of our valveless vapor sampling inlet for on-line analysis of atmospheric gases and vapors by "transfer line" GC/MS to monitor chemical processes at high pressures (1000-2000 psi) through the construction of a special capillary restrictor to reduce the pressure to near ambient conditions. The restrictor effluent is coupled to the automatic vapor-sampling inlet via a dilution chamber. This allows repetitive GC/MS analyses to be obtained at 1-15 minute intervals.

Kinetic parameters and yields of primary and secondary decomposition products of jet fuels as well as model compounds in coal liquefaction processes have been obtained in a fraction of time needed for conventional off-line measurements and indicate that the proposed approach may be easily applied to a broad range of existing reactor types and potential processing environments.

On-Line GC/MS Analysis of High Pressure Conversion Reactions of Model Compounds for Coal-Derived Liquids

Huai, H.; Tsai, C.H.; Shabtai, J.S. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(2):925-932, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Consortium for Fossil Fuel Liquefaction.

Direct coal liquefaction involves complex and insufficiently defined chemical reactions. In order to improve direct coal liquefaction processes, it is necessary to improve our understanding of key chemical reactions. Unfortunately, due to the high pressure and high temperature requirements of most coal liquefaction processes, real-time on-line reaction monitoring by advanced spectroscopic and/or chromatographic techniques has generally been impossible until now. Thus, relatively little is known about the precise reaction pathways as well as the intermediate reaction products involved. This is particularly true for conversion reactions carried out in batch reactors such as autoclaves. Due to the relatively long residence times primary reaction products formed in batch type autoclaves are quite susceptible to secondary, or even tertiary reactions. Consequently, real-time on-line monitoring experiments are needed to elucidate reaction pathways in autoclaves.

Although several on-line systems have been developed for coal conversion at near-ambient pressure or high vacuum conditions, there are no repots of on-line chromatography/spectroscopy based systems built for monitoring high-pressure conversion reactions. Therefore, the development of a direct GC/MS interface for near-real time analysis of high-pressure reaction products, while minimally disturbing the reaction process, has been undertaken in our laboratory.

It is well established that coal contains fused aromatic and hydroaromatic ring clusters, composed of an average of two to tour condensed ring units, connected by various alkylene, ether, sulfide and direct (Ar)C-C(Ar) bridges. Liquefaction reactions are primarily thought to involve these connecting bridges, especially ether linkages and alkylene linkages. In recent years, a number of workers have subjected coal-model compounds to various coal conversion conditions in order to confirm that certain coal structures are reactive during coal conversion and to infer the conversion mechanisms of real coals from mechanisms determined for such compounds.

The present paper reports the design and testing of a newly developed on-line GC/MS monitoring system for high pressure reactions and its application to the investigation of hydrogenation and hydrodeoxygenation (HDO) of model compounds, such as diphenyl methane and dibenzyl ether, under both catalytic and thermal conditions.

Coherent Anti-Stokes Raman Spectroscopy (CARS) in Pulverized Coal Flames

Hancock, R.D.; Boyack, K.W. and Hedman, P.O.
Chapter 15, Advances in Coal Spectroscopy, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1992. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, US Department of Energy and ACERC.

Coherent anti-Stokes Raman spectroscopy (CARS) is a diagnostic technique involving the use of high powered lasers to determine the temperature and concentration of the various major species found in combustion processes. This laser diagnostic technique allows in situ temperature and species concentration measurements to be obtained without disturbing the flame, as would most traditional thermocouples and sampling devices. Furthermore, there is no temperature limit associated with CARS because it is purely an optical technique.

CARS was first introduced by Taran and his co-workers at ONERA in France and was quickly recognized by other researchers throughout the world as a valuable diagnostic technique. Soon, numerous theoretical discussions, innovations, and practical applications of the CARS technique were introduced to the scientific community. CARS research has been implemented by various laboratories in the United States, Canada, England, France, Germany, Japan, and the Soviet Union.

Initially, CARS was applied to clean gas flames. However, as the instrument evolved, its diagnostic strengths were used to probe increasingly complex combustion environments. One such complex environment is that created by the introduction of particles into gas flames. Several researchers have studied such particle-laden flames and found them more difficult to probe, with the resulting CARS spectra more complex to analyze. These researchers have demonstrated that CARS measurements are possible in particle-laden flames.

Particle-laden flames are more difficult to probe because the particles attenuate the laser beams and can induce breakdown. Attenuation of the laser beams results in a loss of beam and signal strength. Breakdown alters the shape and intensity of the experimental spectra. The focus of this study was to develop methods by which consistent CARS measurements could be made on a regular basis in laboratory-scale particle-laden flames with coal loadings similar to those encountered in industrial burners.

This study extended the existing CARS instrument capability at Brigham Young University to a new laminar flame reactor that was designed to study flame speeds in pulverized coal flames. The facility modifications required the CARS laser beams to be transmitted over a 23-meter path length from the optical table to the reactor. The CARS signal was returned from the test chamber to the spectrometer with a fiber optic cable. The CARS signals were analyzed employing a modified version of the fitting code FTCARS from Sandia National Laboratories, using temperature and concentration libraries calculated with the CARS spectra code developed at Mississippi State University.

1991

Canonical Correlation Analysis of Multisource Fossil Fuel Data

Meuzelaar, H.L.C.; Statheropoulos, M.; Huai, H. and Yun, Y.
Computer-Enhanced Analytical Spectroscopy, 3:185-214, (P.C. Jurs, ed.), Plenum Publishing Co., New York, 1991. Funded by ACERC and US Department of Energy.

The following sections of this chapter will demonstrate the application of Canonical Correlation Analysis (CCA) to multisource fossil fuel data generated by the application of three different spectroscopic methods: Pyrolysis Low Voltage Electron Ionization Mass Spectrometry (LVMS); Pyrolysis Field Ionization Mass Spectrometry (FIMS); and Photo-acoustic Fourier Transform Infrared Spectroscopy (FTIR) to a single suite of eight U.S. coals obtained from the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP). Consequently, the three data sets obtained describe the same suite of samples but are markedly different with respect to number as well as type of variables.

Structural Comparison of Low-Molecular-Weight Extractable Compounds in Different Rank Coals Using Capillary Column Gas Chromatography

Chang, H.-C.K.; Bartle, K.D.; Markides, K.E. and Lee, M.L.
Advances in Coal Spectroscopy, 141-164, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1991. Funded by Gas Research Institute and ACERC.

In this chapter, results from the analysis of the low-molecular-weight organic constituents in six vitrinite-rich coals of ranks ranging from lignite to low volatile bituminous are reported. Aliphatics, neutral aromatics, nitrogen-containing aromatics, and sulfur-containing aromatics were first isolated from the coal extracts using column absorption and complexation chromatography, and then they were resolved and identified using capillary column gas chromatography coupled with sulfur- and nitrogen-selective detectors, and mass spectrometry.

C-13 NMR Techniques for Structural Studies of Coals and Coal Chars

Orendt, A.M.; Solum, M.S.; Sethi, N.K.; Pugmire, R.J. and Grant, D.M.
Advances in Coal Spectroscopy, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1991 (in press). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, US Department of Energy and ACERC.

Techniques in C-13 nuclear magnetic resonance spectroscopy applied in the study of coal and coal chars are discussed along with details of the analysis of the spectral results. The results are compared for various methods of analysis: cross polarization with magic angle spinning (CP/MAS), dipolar dephasing (DD), MAS with block decays (BD), and chemical shielding anisotropy (CSA) measurements. Results of the CP/MAS and DD experiments on the Argonne premium coals as well as other coals and coal chars are reported in terms of twelve structural parameters, including aromaticity. Methods used to determine average cluster size and molecular weight are discussed. Models of coal structure and devolatilization processes are presented along with an analysis of the information obtained from the C-13 NMR experiments.

Development of Reliable Coal Oxidation (Weathering) Index Slurry pH and Its Applications

Yun, Y. and Meuzelaar, H.L.C.
Fuel Processing Technology, 27:179-292, 1991. Funded by US Department of Energy and Utah Power and Light.

A simple slurry pH titration method was developed as a means of measuring the degree of mild air oxidation in coal, especially for low rank, non-caking coals. The results show that this pH titration method, with prior rehydration at 150ºC, is a practically useful way of determining the degree of air oxidation of a coal sample of known origin but uncertain weathering status. For coals of a lower rank than high volatile bituminous, this method can be simplified to direct measurement of the slurry pH without the rehydration step. Among the variables influencing the rate of mild air oxidation as measured by the slurry pH, temperature is the most important whereas humidity exhibits little or no effect on the initial slurry pH although it has a marked effect on the pH titration profiles. Use of Curie-point pyrolysis-low voltage mass spectrometry on weathered, subbituminous coal samples from a coal storage pile reveals that the main effect of humidity on the composition of the pyrolyzate appears to involve certain sulfur compounds. Application of the initial slurry pH as an oxidation/weathering index yields an activation energy of oxidation/ weathering in the 20-150ºC range of 50-65 kJ/mol (12-16 kcal/mol) and indicates the existence of several different oxidation mechanisms in the temperature regimes between 60 and 150ºC.

Examination of Coal by Combined Thermogravimetry/Infrared Spectroscopy/Mass Spectrometry

Buchanan, R.M.; Holbrook, K.M.; Meuzelaar, H.L.C. and Leibrand, R.
IRD Application Brief, Hewlett Packard, 23:5091-2022E, 1991.

Combined TG/IR and, to some extent, TG/MS techniques are finding increased application for structure/reactivity studies as well as for characterization and quality control of synthetic polymers, natural products, and fossil fuels. Unfortunately, the high cost of commercially available integrated TG/IR and TG/MS (let alone TG/IR/MS) systems has kept these techniques well out of reach for most analytical laboratories.

The advent of low cost bench-top FTIR and MS systems, however, has opened up the possibility of designing and assembling an affordable combined TG/FTIR/MS system. Such a system, developed at the University of Utah, Center for Micro Analysis, consists of a standard HP GC/IRD/MSD system utilizing an HP 5890 gas chromatograph, an HP 5965A IRD, and an HP 5971A MSD coupled to a Perkin Elmer Model 7 TG with a high temperature (1600? K max.) furnace. A specially constructed heated transfer line assembly allows direct coupling of the TG system to the GC injection port. The GC oven acts as a convenient heated coupling and flow distribution module. In this experiment no chromatography is performed with only sample transfer from the TG directly to the detectors.

Chemical Composition and Origin of Fossil Resins from Utah Wasatch Plateau Coal

Meuzelaar, H.L.C.; Huai, H.; Lo, R. and Dworzanski, J.P.
Fuel Processing Technology, 28:119-134, 1991. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC and Advanced Coal Technology Center.

In order to arrive at a more detailed chemical description of fossil coal associated resins we need to distinguish between micropetrographic, organic geochemical and process technological definitions, each of which may encompass varying quantities of constituents unrelated to fossil tree resins. New information on composition and origin of Utah Wasatch Plateau coal resins obtained by Curie-point pyrolysis/evaporation in combination with iso-butane chemical ionization mass spectrometry, as presented in this paper, points to the presence of four more or less distinct resin components: (1) a sesquiterpenoid polymer; (2) sesqui- and triterpenoid monomers and dimers; (3) a suite of triterpenoid alcohols, ketones and acids; and (4) a series of increasingly aromatized hydrocarbons with naphthalene and picene type skeletons. Moreover, a strong similarity is found between the composition of recent dammar resin and fossil. Wasatch Plateau coal resins indicating a possible Angiosperm (fam. Dipterocarpaceae) origin of these Upper Cretaceous coal resins. Some of the technological implications of these findings and the consequent need for a more precise chemical definition and nomenclature are discussed.

The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam

Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 5:688-694, 1991. Funded by US Department of Energy and ACERC.

The objective of the present study is to examine the chemical structure and composition of Utah Wasatch Plateau coal resinite. Macerals were separated from the coal matrix by hand picking, sink-float treatments, and/or density gradient centrifugation (DGC). DGC separation was found to produce highly purified resinite fractions. Resinite-rich Wattis Seam coal samples were collected from fresh mine faces and, after varying degrees of concentration, subjected to C-13 magic angle spinning NMR, Curie-point pyrolysis MS, and Curie-point pyrolysis GC/MS in addition to petrographic analysis and fluorescence microscopy as well as conventional (e.g., ultimate analysis) characterization methods. The data obtained confirm recent findings indicating that the abundant blue/green fluorescing resinite component is a polymeric substance composed of sesquiterpenoid repeat units with a median size of 204 Da, corresponding to the empirical formula C15H24. The monomeric sesquiterpenoid units obtained during pyrolysis appear to represent different degrees of unsaturatization ranging from C15H26 sesquiterpenes to the aromatic C15H18 cadalene. Clearly, sesquiterpenoids constitute the bulk of extractable resinite in Wasatch Plateau field coal and are likely to be important precursors of the abundant extractable alkynaphthalene moieties in such coal.

Vacuum Pyrolysis Mass Spectrometry of Pittsburgh #8 Coal; Comparison of Three Different, Time-Resolved Techniques

Yun, Y.; Meuzelaar, H.L.C.; Simmleit, N. and Schulten, H.R.
Energy & Fuels, 5:22-29, 1991. Funded by ACERC.

Three different vacuum pyrolysis mass spectrometry techniques, viz. Pyrolysis-Field Ionization Mass Spectrometry, Thermogravimetry/Low Voltage Electron Ionization Mass Spectrometry and Curie-point Pyrolysis-Low Voltage Electron Ionization Mass Spectrometry were used to analyze samples of Pittsburgh #8 coal obtained from the Argonne National Laboratory Premium Coal Sample Program. The primary objective was to assess the effects of differences in experimental techniques and conditions, e.g., with regard to heating rates, pyrolysis methods and soft ionization procedures (FI vs. Low Voltage EI) on the mass spectral patterns. A second objective was to further characterize and study the pyrolysis behavior of Pittsburgh #8 coal. The results indicate that the distribution and the type of the primary pyrolysis products are largely independent of marked differences in heating rate (10-2 K/s - 104 K/s range) and sample size (2.5 x 10-5g - 5.0 x 10-2g range) as well as overall vacuum pyrolysis MS configurations and conditions used. All three vacuum pyrolysis MS techniques produce remarkably similar mass spectral patterns when analyzing Pittsburgh #8 coal. The results show that Pittsburgh #8 coal contains a significant amount of low temperature (<380ºC) evolving "bitumen" consisting primarily of alkyl-substituted aromatic components. The bitumen evolution step is followed by a partially overlapping "bulk pyrolysis" step characterized by the evolution of abundant hydroxy- and dihydroxy substituted aromatic compounds, thought to be primarily derived from vitrinitic components. During the bitumen evolution step the average MW of the compounds increases with temperature while maintaining a relatively narrow distribution. By contrast, during the bulk pyrolysis step, the average MW tends to decrease while exhibiting a much broader distribution.

Laser Pyrolysis Gas Chromatography/Mass Spectrometry of Single Spherocarb Particles Impregnated with Bituminous and Polymeric Substances

Maswadeh, W.; Huai, H. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):733-740, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by ACERC.

A major bottleneck in the development of novel coal characterization methods, such as laser pyrolysis GC/MS, capable of analyzing individual coal particles, is the unavailability of suitable standard samples. Although carefully homogenized and characterized standard coals are now available through the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP) such "statistically homogenous" coal powders are of limited value as reference materials for single particle analysis methods. Even if it would be feasible to prepare particles of closely similar chemical composition and size, e.g., by using highly concentrated coal maceral fractions and careful sieving, remaining variations in shape, density, porosity or thermal conductivity could still introduce an unacceptably high level of uncertainty for most optimization and calibration purposes.

In an attempt to find model coal char particles with well-defined chemical and physical properties, e.g., for the purpose of modeling char oxidation reactions, several authors have used Spherocarb® particles. Flagan et al have even prepared spherical char particles spiked with mineral matter components in order to more closely mimic actual coal char particles. Although Spherocarb particles still show considerable variability with regard to size (rel. s.d. ~20% on a volume basis), other characteristics such as shape, density, porosity, thermal conductivity and chemical composition are assumed to be quite constant.

Unfortunately, Spherocarb particles are of little value for modeling coal devolatilization reactions due to their very low volatile matter yields. This prompted us to think of ways to increase volatile matter yields by introducing a variety of model compounds, ranging from low molecular weight, bitumen-like components to polymeric materials such as soluble lignins or resins. To the best of our knowledge this article represents the first reported use of bitumen and polymer impregnated Spherocarb particles for modeling devolatilization processes in individual coal particles.

Characterization of Lignocellulosic Materials and Model Compounds by Combined TG/(GC)/FTIR/MS

Dworzanski, J.P.; Buchanan, R.M.; Chapman, J.N. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):725-732, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC, Hewlett Packard Corp. and US Department of Energy.

Thermal analytical methods have been widely used during the last two decades in the study of biomass thermochemical conversion processes. Biomass, which represents a renewable energy resource, consists primarily of plant cells differentiated into characteristic tissues and organs. Lignins, hemicelluloses and cellulose, as the main components of the cell walls, were therefore extensively analyzed, especially from the point of view of their thermochemical reactivity, which is of basic importance for industrial processing of biomass.

All types of cellulose microfibrils are composed of linearly linked b-(1-->4)-D-glucopyranose units and differ only by the degree of polymerization. The remaining polysaccharides are known collectively as hemicelluloses and exhibit species related composition. These amorphous, complex heteropolymers characterized by a branched molecular structure exhibit a lower degree of polymerization than cellulose. Xylan is the predominant hemicellulose component of angiosperms ("hardwoods") whereas mannan forms the main hemicellulose of gymnosperms ("softwoods"). The third principal component of biomass, viz. lignin, is an irregular, high MW polymer formed by enzyme-initiated, free-radical polymerization of coniferyl alcohol (in hardwoods), coniferyl plus sinapyl alcohols (in softwoods), or coumaryl alcohol plus both above mentioned alcohols (in grasses). Lignins act as binding agents for the cellulose and hemicellulose fibers through a variety of linkages involving ether and carbon-carbon bonds of aromatic rings and propyl side chains.

Thermochemical conversion processes of lignocellulosic materials have been studied using mainly thermogravimetry (TG) or flash pyrolysis (Py) followed by gas chromatographic (GC) separation and identification of the reaction products. Modern analytical techniques based on coupled Py-GC/mass spectrometry (Py-GC/MS) or direct Py-MS as well as TG/MS or TG/infrared spectroscopy (TG/IR) have proved to be especially useful for elucidating the relationships between biomass structure and pyrolysis/devolatilization mechanisms.

A novel TG/(GC)/FTIR/MS system developed at the University of Utah, Center for Micro Analysis and Reaction Chemistry provides the opportunity for combining accurate weight loss measurements with precise information about composition and evolution rates of gaseous and liquid products as a function of temperature. In this paper, the usefulness of TG/FTIR/MS, TG/GC/MS and TG/GC/FTIR for thermochemical characterization of wood, lignins and cellulose will be discussed.

Laser Pyrolysis GC/MS of Single Coal and Coal Model Particles

Maswadeh, W. and Meuzelaar, H.L.C.
Proceedings of the 39th ASMS Conference on Mass Spectrometry and Allied Topics, 192-193, Nashville, TN, May 1991. Funded by ACERC.

Laser pyrolysis GC/MS using an electronically pulsed cw CO2 laser focused at the center of a Paul trap type particle levitation device connected to a Paul trap type spectrometer (Finnigan MAT ITMS) by means of a short, ballistically heated capillary GC column has proved to be a valuable technique for studying the devolatilization (pyrolysis + desorption) behavior of single, 100-150 µm sized coal particles at very high heating rates (105-106 K/s).

A modified experimental set-up, has been designed in which an electrodynamic balance cell is replaced with a simple electron microscopy (EM) grid (400 mesh, 78% open) to support and stabilize particles while providing markedly improved collection efficiency for laser pyrolysis and desorption products. Comparison of the two GC/MS profiles shows a high degree of qualitative similarity while illustrating the higher yield and improved signal to noise ratio of the EM grid technique. The improved signal quality is especially important for detecting and identifying minor components, reflecting subtle changes in pyrolysis mechanisms as a result of the high laser heating rate.

Analysis of Peru Margin Surface Sediments by PY-MS

Eglinton, T.I.; McCaffrey, M.A.; Huai, H. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 36(2):781-789 (201st ACS National Meeting, Atlanta, GA, April 1991).

In offshore Peru high sedimentary organic carbon contents are a direct consequence of the extremely high primary productivity (ca. 1000g Carbon m²/yr) which, in turn, is supported by the upwelling of nutrient-rich waters near the coast. Diatoms represent the major phytoplankton type and give rise to sediments dominated by biogenic silica and planktonic organic matter. The remineralization of this large flux of organic matter to the bottom waters and sediments results in oxygen depletion over large areas of the shelf that, in turn, promotes organic carbon preservation in the underlying sediments. Sulfide from sulfate reduction is prevalent in the bottom waters and with a limited availability of iron (due to the dominant biogenic input coupled with a very low influx of detrital sediments) the excess sulfide is available for reaction with the organic matter. As a result high organic sulfur concentrations are found in the sediments.

The coastal Peru upwelling region is believed to be a modern analogue to the depositional environments of petroleum source rocks such as the Miocene Monterey Formation of the California Borderland. Because organic matter alteration pathways in surface sediments ultimately influence kerogen type and eventual petroleum yield, there has been interest in characterizing surface sediments such as those offshore Peru. Lipid, carotenoid and amino acid constituents as well as general biogeochemistry have been studied previously. However, studies of the macromolecular components of the sediments have been less extensive. This paper describes results from Py-MS analyses of sediment samples obtained from discrete intervals in a 1-meter core obtained from the upper continental shelf of the Peru Upwelling region. Factor and discriminant analysis of the Py-MS data revealed several distinct changes within this 1-meter section.

On-Line Monitoring of Formaldehyde in Comubustion Gases Using Gas Chromatography/Mass Spectrometry

McClennen, W.H.; Sheya, S.A.N.; Arnold, N.S.; Meuzelaar, H.L.C.; Deng, X.-X.; Larsen, F.S. and Silcox, G.D.
Combustion Science and Technology, 1991 (in press). Funded by ACERC.

This paper describes a method for on-line gas chromatography/mass spectrometry (GC/MS) of formaldehyde in combustion gases. The method uses a recently developed vapor-sampling inlet to monitor the concentration of formaldehyde and other products of incomplete combustion (PICs) from the burning of plain and phenol-formaldehyde resin treated wood chips. Other PICs that were simultaneously monitored included ketene, propylene, propyne and acetaldehyde. The direct analysis method has detection limits of less than 1 ppm for the reactive formaldehyde and excellent selectivity for determinations in the complex mixtures of combustion products. The rapid sampling technique allows monitoring of transient events of only a few minutes or less duration. Examples of the technique include the detection of sample line problems and the comparison of PIC concentrations from different points in the combustion exhaust stream.

Vapor Sampling Device for Direct Short Column Gas Chromatography/Mass Spectrometry Analyses of Atmospheric Vapors

Arnold, N.S.; McClennen, W.H. and Meuzelaar, H.L.C.
Analytical Chemistry, 63:299-304, 1991. Funded by ACERC.

A number of methods are currently used for atmospheric vapor and gas sampling with mass spectrometric detection and identification. Direct mass spectrometry (MS) sample introduction methods include fixed molecular tasks, atmospheric pressure ionization, trap and desorb, and membrane separation, while gas chromatography/mass spectrometry (GC/MS) methods employ trap and desorb, direct bubbler solvent injection, sample loops, and pressurized gas plug introduction. Approaches vary depending upon whether MS, tandem MS, or GC/MS analyses are desired. Direct MS and tandem MS analyses typically give quick response times and high repetition rates but are often sensitive to interferents, including atmospheric constituents, while GC/MS analyses offer greater specificity but with typically lower results.

Hand-Portable Gas Chromatography/Ion Mobility Spectrometry: The "Poor Man's" CB System?

Meuzelaar, H.L.C.; Kim, M.-G.; Arnold, N.S.; Kalousek, P. and Snyder, A.P.
US Army Research Office Workshop on Spectrometry and Spectroscopy for Biologicals, Cashiers, NC, 1991. Funded by US Army/Chemical Research Development and Engineering Center and US Department of Defense/Army Research Office.

The capabilities of ion mobility spectrometry (IMS) with regard to the detection and identification of chemical warfare agents are widely recognized. Tens of thousands of IMS based CAM® (Chemical Agent Monitor) systems manufactured by Graseby Ionics (Watford, U.K.) are currently in use by NATO forces, including US Army Marine Corps.

The hand-held, battery powered CAM draws approx. 500 ml. min-1 of ambient air over a heated silicone rubber membrane covering the entrance to the ionization chamber (a Ni-63 source) and the IMS drift tube region both of which are being operated slightly below ambient pressure. A Faraday cup detector registers the arrival time of mobile ion species traversing the drift tube at different velocities after being admitted into the drift tube region by gating pulses at 20 msec intervals. Typical drift times ("mobilities") of ion species representing volatile organic compounds are in the 5-10 msec range. The CAM can be operated in either positive or negative ion detection mode (switch selectable).

In spite of the successful development and application of the CAM for detecting chemical warfare agents, several remaining shortcomings inherent to IMS based detection devices (e.g., limited ability to distinguish between individual components in complex mixtures as well as low dynamic range and lack of linear response), seriously hamper its application as a quantitative detection tool. Moreover, only organic species that readily pass through the silicone rubber membrane can be detected. This prevents the use of the CAM for detection of nonvolatile materials such as most biological warfare agents.

Feasibility of Drone-Portable Ion Mobility Spectrometry

Arnold, N.S.; Meuzelaar, H.L.C.; Dworzanski, J.P.; Cole, P.C. and Snyder, A.P.
US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense Research, Arberdeen Proving Grounds, MD, November 1991. Funded by US Department of Defense/Army Research Office.

The feasibility of telemetry based, drone-portable IMS (ion mobility spectrometry) and GC/IMS (gas chromatography/-ion mobility spectrometry) for real-time detection and monitoring of atmospheric concentrations of target vapors in otherwise inaccessible locations has been demonstrated using primarily "off the shelf" technology. The test configuration involved a Graseby Ionics CAM (Chemical Agent Monitor) with an ASP type PC interface, a Compaq 386 mother-board with 1 Mbyte RAM, two H-Cubed Corp. and Tekk Corp. digital radio transmitter and receiver sets, CoSession (Triton Technology) communications software and a remote, 386 level computer workstation. On-board system components weigh <15 lbs and use <30W of battery power. Preliminary test results indicate the feasibility of transmitting ion mobility data at up to 9600 baud, corresponding to approximately 20 spectra per minute. Typical range of the tested transceiver system is 1-2 miles. Potential applications include military or law enforcement operations as well as environmental and industrial screening or monitoring.

Remotely Operated, Field Portable Gas Chromatography/Mass Spectrometry System for Monitoring Hazardous Atmosphere Vapors

Arnold, N.S.; Urban, D.T.; Watteyne, R.L.; Cole, P.C. and Meuzelaar, H.L.C.
Proceedings of the 39th Annual ASMS Conference on Mass Spectrometry and Allied Topics, 671-672, Nashville, TN, May 1991. Funded by US Department of Defense and ACERC.

In order to protect and inform personnel involved in monitoring, containment and remediation of hazardous volatiles materials, it is important that exposure to such materials be limited and that personnel working in such environments have sensitive and easily handled tools that do not limit mobility or vision. In order to meet these requirements a man-portable GC/MS system described previously has been modified to meet four objectives: (1) to allow remote instrument operation via a serial data transfer protocol compatible with broadband radio telemetry; (2) to reduce system size for placement in a single backpack or in a small, unmanned reconnaissance plane (drone); (3) to reduce system weight under 50 lbs for worker mobility in man-portable mode and to meet payload requirements for drone aircraft; (4) to increase pumping speed for greater sample throughput and lower detection limits.

The Application of a Mobile Ion Trap Mass Spectrometer System to Environmental Screening and Monitoring

McClennen, W.H.; Arnold, N.S.; Meuzelaar, H.L.C.; Ludwig, E. and Lighty, J.S.
2nd International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1991. Funded by ACERC, Environmental Protection Agency, Finnigan MAT Corp., US Army Chemical Research Development and Engineering Center and Utah Power and Light.

This paper presents examples of the use of a mobile Ion Trap Mass Spectrometer (ITMS, Finnigan MAT) for on-site environmental screening and monitoring of vapors by gas chromatography/mass spectrometry (GC/MS). The instrument is built around a miniaturized ITMS system, with a novel direct vapor-sampling inlet and coupled to a high-speed transfer line GC column (short capillary column with fixed pressure drop). The column is temperature controlled inside the standard ion trap transfer line housing. This provides for high-speed analyses at 10-60 s intervals using an automated sampling system constructed with only inert materials in the sample path.

Specific laboratory and field applications exemplify key characteristics of the system including sensitivity, specificity for a broad range of compounds, ruggedness for field-testing in harsh environments, and general speed for field-testing in harsh environments, and general speed and versatility of the analytical technique. The system has been calibrated for alkylbenzenes at concentrations as low as 4 ppb in air and used to monitor these compounds in an office space. Both the MINITMASS and a simpler Ion Trap Detector (ITD) based system have been used to monitor organic vapors from acetone through 5 ring polycyclic aromatic hydrocarbons produced in laboratory scale reactors for studying the thermal desorption and incinerations of hazardous wastes. The ruggedness of the MINITMASS system has been demonstrated by vapor sampling in the Utah summer desert and at a 600 MW coal fired power plant. Finally, the analysis speed and versatility are described for vapor monitoring of volatile organic compounds at an EPA national priority list waste site.

Development and Testing of a Man-Portable Gas Chromatography/Mass Spectrometry System for Air Monitoring

Meuzelaar, H.L.C.; Urban, D.T. and Arnold, N.S.
2nd International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1991. Funded by Environmental Protection Agency, US Department of Defense, Finnigan MAT Corp., Utah Power and Light, Hewlett Packard Corp. and ACERC.

In situations involving special military or law enforcement operations, as well as industrial accidents or natural disaster, mobile laboratories may be of little use because of limited site access restrictions due to contamination or terrain constraints. Under such conditions man-portable analytical instruments may offer the only acceptable means of carrying out on-site analyses. The current prototype weighs approx 70-75 lbs and uses 150-200 W of battery power. The mass spectrometer and computer are carried in front of the operator by means of a shoulder harness whereas battery pack, carrier gas supply and roughing vacuum system are carried as a backpack. Air samples can be analyzed using a special automated air-sampling inlet. The man-portable GC/MS system is supported by a vehicle transportation "docking station."

1990

Computer-Enhanced Analytical Spectroscopy, Volume II

Meuzelaar, H.L.C., Editor
Plenum Publishing Corporation, 1990 (In press). Funded by ACERC (National Science Foundation and Associates and Affiliates).

The Second Hidden Peak Symposium on Computer-Enhanced Analytical Spectroscopy, held in June, 1988, at the Snowbird Resort (Salt Lake City, Utah), centered around twelve keynote lectures delivered by some of the foremost experts and pioneers in this rapidly expanding field. The primary objective of this volume is to present a representative cross-section of current activities in the field while balancing out the lighter coverage of some topics and areas in Volume I.

An exciting new topic, remote IR sensing, is covered in Chapters 4 and 5. Deconvolution and signal-processing methods have now been extended to UV/VIS (Chapter 1) and GC/MS (Chapter 3) applications. Furthermore, the development and testing of novel factor analysis techniques in the areas of UV/VIS and IR spectroscopy are discussed in Chapters 2 and 12, respectively. Fundamental aspects of library search techniques are presented in Chapters 7 (MS) and 9 (NMR). Chapters 6, 10, and 11 cover selected uses of expert systems in IR, NMR, and MS, respectively. Finally, an integrated expert system approach to the interpretation of GC/IR/MS data is outlined in Chapter 8.

In an attempt to facilitate access to the various topics for the newcomer to the field, the twelve chapters have been organized into two main parts: Unsupervised Methods: Spectral Enhancement, Deconvolution, and Data Reduction, and Supervised Methods: Expert Systems, Modeling, and Quantitation.

All in all, the second volume is intended to constitute a logical complement to Volume I. Consequently, for a more comprehensive update of developments in the field over the past five years or so, the reader is encouraged to consult both Volume I and Volume II.

Thermochemical Analysis of U.S. Argonne Premium Coal Samples by Time-Resolved Pyrolysis Field Ionization Mass Spectrometry

Simmleit, N.; Yun, Y.; Meuzelaar, H.L.C. and Schulten, H.R.
Advances in Coal Spectroscopy, Meuzelaar, H.L.C., Editor, Plenum Publishing Corp., New York, 1990 (In press). Funded by ACERC (National Science Foundation and Associates and Affiliates).

Analytical pyrolysis techniques are widely used for the thermochemical analysis of coals and coal-derived products. During heating, complex mixtures of chemical substances are released from coal by distillation, desorption and thermal degradation processes. The amount and chemical nature of the volatilized coal products are dependent mainly on the composition and structure of the coal and on heating conditions. Therefore, the results of chemical analyses of the volatilized coal products should provide information on the original structure of coal. For detailed on-line analysis of volatilized coal products usually chromatographic and/or spectroscopic methods have been used. For positive identification of compounds gas chromatography/mass spectrometry (GC/MS) is a common approach, e.g. in direct combination with pyrolysis techniques. However, due to the relatively long analysis times, in particular for high molecular weight products, GC/MS is not suited for a universal on-line monitoring of evolving coal products during heating. For rapid fingerprinting of volatilized coal products on a molecular basis direct MS analysis is often the preferred method. Small amounts of coal or coal-derived products are heated in front of the ionization region under high vacuum conditions. Depending on the type of mass spectrometer used and the experimental conditions, on-line monitoring of evolving coal products is possible for a wide range of heating rate. Heating rates as low as 10-2 C/s may be used in the combined thermogravimetry (TG)/MS whereas heating rates in the 104 - 106 C/s range can be obtained by CO2 laser heating.

Computer-Enhanced Pyrolysis Mass Spectrometry: A New Window on Coal Structure and Reactivity

Meuzelaar, H.L.C., Editor
Computer-Enhanced Analytical Spectroscopy, Volume II, Plenum Publishing Corporation, 1990 (In press). Funded by ACERC (National Science Foundation and Associates and Affiliates).

Coals may be regarded as highly complex, fossilized assemblages of more or less strongly decomposed plant matter, microorganisms and humic substances in addition to a range of possible mineral constituents. Specific coal seams may represent peat-forming palaeoenvironments as diverse as river delta swamps, salt water marshes or rain forest bogs, thus explaining the intrinsic heterogeneity of coal at the macroscopic as well as microscopic levels. Macroscopically, coal heterogeneity is often readily visible in the form of discrete bands representing successions of different depositional environments or, perhaps, catastrophic events such as floods and forest fires. At the microscopic level most coals display an even broader scale of diversity and heterogeneity in the form of microscopically distinct coal components generally referred to as "macerals."

C-13 NMR Techniques for Structural Studies of Coals and Coal Chars

Orendt, A.M.; Solum, M.S.; Sethi, N.K.; Pugmire, R.J. and Grant, D.M.
Advances in Coal Spectroscopy, Meuzelaar, H.L.C., Editor, Plenum Publishing Corp., New York, 1990 (In press). Funded by ACERC and US Department of Energy.

Techniques in C-13 nuclear magnetic resonance spectroscopy applied in the study of coal and coal chars are discussed along with details of the analysis of the spectral results. The results are compared for various methods of analysis: cross polarization with magic angle spinning (CP/MAS), dipolar dephasing (DD), MAS with block decays (BD), and chemical shielding anisotropy (CSA) measurements. Results of the CP/MAS and DD experiments on the Argonne premium coals as well as other coals and coal chars are reported in terms of twelve structural parameters, including aromaticity. Methods used to determine average cluster size and molecular weight are discussed. Models of coal structure and devolatilization processes are presented along with an analysis of the information obtained from the C-13 NMR experiments.

The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam

Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 1990 (In press). Funded by ACERC and US Department of Energy.

Although the maceral resinite occurs in most U.S. coals, it is particularly abundant in the coal seams of the Wasatch Plateau coalfield in central Utah. The high resinite content of the coals of central Utah has long been known and commercially exploited but little work has been reported on the elucidation of the chemical composition of this material. Details of the chemical structure of the micropetrographically defined maceral resinite have generally been lacking because it is noncrystalline and is only partially soluble in organic solvents. In contrast with the abundance of spectroscopic and chromatographic data available on some of the better known fossil resin types, e.g., Baltic amber, Utah coal resins appear to have generated relatively little interest among coal scientists. The overall objective of the present study was to examine the structure of Utah Wasatch Plateau coal resinite macerals that have been separated from the coal matrix, purified, and most important, carefully characterized by fluorescence spectral analysis. The samples were then analyzed by means of CP/MAS C NMR and by Curie-point pyrolysis in direct combination with mass spectrometry (Py-MS) or via preseparation by gas chromatography (Py-GC/MS).

Vacuum Pyrolysis Mass Spectrometry of Pittsburgh #8 Coal; Comparison of Three Different, Time-Resolved Techniques

Yun, Y.; Meuzelaar, H.L.C.; Simmleit, N. and Schulten, H.R.
Energy & Fuels, 1990 (In press). Funded by ACERC.

Three different vacuum pyrolysis mass spectrometry techniques, viz. Pyrolysis-Field Ionization Mass Spectrometry, Thermogravimetry/Low Voltage Electron Ionization Mass Spectrometry and Curie-point Pyrolysis-Low Voltage Electron Ionization Mass Spectrometry were used to analyze samples of Pittsburgh #8 coal obtained from the Argonne National Laboratory Premium Coal Sample Program. The primary objective was to assess the effects of differences in experimental techniques and conditions, e.g., with regard to heating rates, pyrolysis methods and soft ionization procedures (FI vs. Low Voltage EI) on the mass spectral patterns. A second objective was to further characterize and study the pyrolysis behavior of Pittsburgh #8 coal. The results indicate that the distribution and the type of the primary pyrolysis products are largely independent of marked differences in heating rate (10-2 K/s - 104 K/s range) and sample size (2.5 x 10-5g - 5.0 x 10-2g range) as well as overall vacuum pyrolysis MS configurations and conditions used. All three vacuum pyrolysis MS techniques produce remarkably similar mass spectral patterns when analyzing Pittsburgh #8 coal. The results show that Pittsburgh #8 coal contains a significant amount of low temperature (<380ºC) evolving "bitumen" consisting primarily of alkyl-substituted aromatic components. The bitumen evolution step is followed by a partially overlapping "bulk pyrolysis" step characterized by the evolution of abundant hydroxy- and dihydroxy substituted aromatic compounds, thought to be primarily derived from vitrinitic components. During the bitumen evolution step the average MW of the compounds increases with temperature while maintaining a relatively narrow distribution. By contrast, during the bulk pyrolysis step, the average MW tends to decrease while exhibiting a much broader distribution.

Modeling and Predicting the Composition of Fossil Fuel Derived Pyrolysis Liquids by Using Low-Voltage Mass Spectrometry and Canonical Correlation Analysis

Chakravarty, T.; Khan, M.R. and Meuzelaar, H.L.C.
Industrial and Engineering Research, 29 (11), 2173-2180, 1990. Funded by Consortium for Fossil Fuel Liquifaction Science.

Low-voltage electron ionization mass spectrometry (LV-EIMS) was performed on 25 fossil fuel samples (21 coals, 2 oil shades, 1 tar sand, and 1 coal resin concentrate) and their respective pyrolysis liquids prepared at Morgantown Energy Technology Center (METC) by means of a fixed-bed reactor. By using principal component analysis, the tar evaporation spectra and the solid fuel pyrolysis spectra were classified in terms of the underlying structural variables. In both data sets, all 4 non-coal samples, as well as 2 less typical coal samples, were found to be outliers. After removing the 6 outliers, canonical correlation analysis was performed on the remaining subsets of 19 coal samples in order to bring out the compositional similarities and differences between the fossil fuel samples and their pyrolysis liquids. By determining the common sources of variance between the two data sets by means of canonical correlation analyses, it was demonstrated that the canonical variate model enabled prediction of the mass spectrum of a given coal tar sample from the measured pyrolysis mass spectrum of the corresponding coal sample. Agreement with the experimental results was reasonably good.

Comparison of Low-Voltage Electron Ionization and Field Ionization Mass Spectra of Coal-Derived Liquids from the Wilsonville Pilot Plant

Taghizadeh, K.; Hardy, R.H., Davis, B.H. and Meuzelaar, H.L.C.
Fuel Processing Technology, 1990 (In press). Funded by Consortium for Fossil Fuel Liquifaction Science, Commonwealth of Kentucky, Kentucky Energy Cabinet and US Department of Energy.

Low voltage - Electron Ionization (LV-EI) and Field ionization (FI) mass spectra of coal-derived liquids (CDLs) obtained from the Wilsonville Coal liquefaction pilot plant before and after hydrotreatment were compared. LV-EIMS (12 eV) analysis of Wilsonville CDL'S before and after hydrotreatment produces very similar spectral patterns as obtained by FIMS. This is especially true for the more highly aromatic hydrotreater feed samples since the hydroaromatic compounds that dominate the hydrotreater product sampler tend to fragment more under LV-MS conditions. Canonical variate analysis confirms that the mass spectral patterns produced by both techniques are highly correlated with the exception of the higher mass range (above m/z 300) that is severely under-represented in the LV-EIMS patterns, due to lower inlet temperatures and to mass discrimination effects in quadrupole MS systems. Furthermore, in spite of the highly complex nature of the original spectral profiles, use of multivariate statistical analysis techniques, such as factor analysis and canonical correlation analysis, enables "numerical extraction" of simplified spectral patterns which can be tentatively interpreted in terms of chemical components or compound series.

Mass Spectrometric Studies of the Chemical Composition of Coal Tars Produced in a Laminar Flow Reactor

Lo, R.; Pugmire, R.J.; Fletcher, T.H. and Meuzelaar, H.L.C.
Preprints for Papers Presented at the 200th ACS National Meeting, 35 (3), 697-704, Washington, D.C., 1990. Funded by ACERC and Consortium for Fossil Fuel Liquifaction Science.

Curie-point desorption in combination with Gas Chromatography/Mass Spectrometry (GC/MS) and, alternatively, with direct Low Voltage Mass Spectrometry (LV-MS) was used to investigate the chemical composition and structure of condensed tar vapors produced during rapid devolatilization (heating rate ~10,000 K/sec) of carefully sized coal particles representing the Beulah Zap, Big Blue, Illinois #6, Pittsburgh #8, and Pocahontas #3 seams, respectively, using the laminar flow reactor described by Fletcher et al at two gas temperatures (1050 K and 1250).

Tar samples were collected by means of a special probe at different points downstream of and corresponding to residence times between 70 and 250 ms. GC/MS analyses of the corresponding tars indicate that the degree of aromaticity increased rapidly as a function of residence time at the 1250 K gas temperature condition. Moreover, at 1250 K devolatilization is complete within 70 ms and beginning secondary gas phase reactions of tar vapors (viz. marked increases in PNAH content and corresponding decreases in phenolic components) are observed within less than 100 ms. However, at 1050 K the coal devolatilization process appears to be barely complete after 250 ms and little or no evidence of secondary gas phase reactions is found.

Laser Pyrolysis-Transfer Line Chromatography/Mass Spectrometry of Single, Levitated Coal Particles

Maswadeh, W.; Arnold, N.S. and Meuzelaar, H.L.C.
Proc. of the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, AZ, 599-600, 1990. (Also presented at Pyrolysis 90, Amsterdam, The Netherlands, 1990; ACS Joint 45th Northwest/Rocky Mountain Regional Meeting, Salt Lake City, UT, 1990; ACS Division of Fuel Chemistry and Preprints for Papers Presented at the 200th ACS National Meeting, 35 (3), 755-762, Washington, D.C., 1990). Funded by ACERC.

A laser pyrolysis transfer line gas chromatography/mass spectrometry (laser Py-TLGC/MS) system based on the combination of an electronically pulsed CW C02 laser with an electrodynamic balance (EDB), a heated capillary ("transfer line") GC column and an ion trap mass spectrometer (ITMS) was constructed.

The main purpose of the system is to study the devolatilization behavior of single, levitated coal particles at very high heating rates, e.g., 105 - 106 K/sec, while comparing the composition of the devolatilization products to those observed at much lower heating rates, e.g., 10-2 - 10-2 K/sec.

Development of Novel, Mass Spectrometric Combustion Monitoring Techniques

McClennen, W.H.; Arnold, N.S.; Sheya, S.A.N.; Lighty, J.S. and Meuzelaar, H.L.C.
Preprints for Papers Presented at the 200th ACS National Meeting, 35 (3), 713-720, Washington, D.C., 1990. Funded by ACERC.

An on-line gas and vapor analysis method has been developed to monitor combustion products by short column ("transfer line") Gas Chromatography/Mass Spectrometry. An automated vapor-sampling inlet with only inert materials (quartz and fused silica) in the sample path is utilized to introduce flue gases into a 1 m long "transfer line" capillary GC column for rapid, repetitive chromatographic separation of products. The column effluent is introduced directly into the source of an ion trap type mass spectrometer. Combustion products from a gas fired rotary kiln were monitored by this method using a standard Ion Trap Detector (ITD). Detection limits of 20 to 50 ppb were obtained for various substituted benzenes. Monitoring of polycyclic aromatic hydrocarbons (PAHs) from the thermal desorption of contaminated soils in a fixed bed reactor utilized a modified Ion Trap Mass Spectrometer (ITMS). Varying isothermal column temperature allowed analysis of PAHs from naphthalene through 6 ring PAHs. The ITMS system provides higher sensitivity (~4 ppb for benzene) in addition to tandem MS and chemical ionization capabilities for unambiguous identification of combustion products incompletely resolved by the transfer line GC approach.

A High Performance Thermogravimetry/Infrared Spectroscopy/Mass Spectrometry System Based on Standard Analytical Components

Holbrook, K.M.; Buchanan, R.M. and Meuzelaar, H.L.C.
Proc. of the 38th ASME Conference on Mass Spectrometry and Allied Topics, 900-901, Tucson, AZ, 1990. Funded by ACERC and Hewlett Packard Corp.

Combined TG/IR and, to some extent, TG/MS techniques are finding increased application for structure/reactivity studies as well as for characterization and quality control of synthetic polymers, fossil fuels and natural products. Unfortunately, the high cost of most integrated TG/MS and TG/IR (let alone TG/MS) systems has kept these techniques well out of reach for most analytical laboratories.

Development of a Man-Portable Transfer Line GC/MS System for Direct On-Site Monitoring of Environmental Vapors

Urban, D.T.; Arnold, N.S. and Meuzelaar, H.L.C.
Proc. of the 38th ASMS Conference on Mass Spectrometry and Allied Topics, 615-616, Tucson, AZ, 1990. Funded by ACERC and Hewlett Packard Corp.

In many potentially dangerous situations of environmental contamination from volatile organic compounds, rapid on-site analysis is essential to the protection of human life. Mobile GC/MS laboratories have been developed for this purpose, yet in many situations terrain limitations or decontamination worries make a vehicle-based system undesirable. To circumvent this vehicular limitation and provide in-situ analysis, a man-portable transfer line GC/MS system is being developed.

A Comparative Study of Eight U.S. Coals by Several Different Pyrolysis Mass Spectrometry Techniques

Huai, H.; Lo, R.; Yun, Y. and Meuzelaar, H.L.C.
ACS Division of Chemistry, 35 (3), Washington, D.C., 1990. (Also Proc. of the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, AZ, 601-602, 1990). Funded by Consortium for Fossil Fuel Liquefaction Science.

Eight U.S. coals of different rank and/or composition, obtained through the Argonne National Laboratory Premium Coal Sample Program, were analyzed by means of several different pyrolysis-MS (Py-MS) techniques, namely: direct Curie-Point Py-MS, Curie-point Py-GC/MS (including GC/EIMS, GC/CIMS and "short column" GC/CIMS), and vacuum thermogravimetry/MS (TG/MS). The data obtained were compared to Pyrolysis-Field Ionization MS (Py-FIMS) data.

The results show a very good agreement between all techniques used in spite of the marked differences in pyrolysis techniques (Curie-point, furnace, direct probe), "soft" ionization methods (low voltage EI, CI FI) and mass spectrometer types (quadrupole, ion trap, magnetic sector) used. As might be expected, the most pronounced variations between techniques appear to be due to mass dependent differences in ion transmissivity and detector response, with the type of soft ionization method taking second place and the type of pyrolysis technique showing least effect on the results. Whereas Py-FIMS provides the most complete and detailed overview of the coal pyrolysis tars, Cuire-point Py-MS and TG/MS methods provide more reliable information on relatively light gaseous products, and Curie-point Py-GC/MS shows the detail composition of the 2/3 of the total pyrolysis tars.

The Mobile Phase in Coal Viewed from a Mass Spectrometric Perspective

Yun, Y.; Meuzelaar, H.L.C.; Simmleit, N. and Schulten, H.R.
Recent Advances in Coal Science: A Symposium in Remembrance of Peter H. Given, Schobert, H.; Bartle, K. and Lynch, L., Editors, ACS Symposium Series, American Chemical Society, Washington, D.C., 1990 (In press). Funded by ACERC.

Seven Argonne Premium coal samples ranging from lignite to low volatile bituminous in rank were analyzed by Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS) in order to determine the existence and structural nature of a thermally extractable "mobile phase." In addition, Curie-point Pyrolysis-Low Voltage Mass Spectrometry (Py-LVMS) was employed to demonstrate the importance of mild oxidation on the thermally extractable mobile phase components. Py-FIMS results clearly reveal the existence of a thermally extractable, bitumen-like fraction which is chemically distinct from the remaining coal components.

Py-FIMS results clearly reveal the existence of a thermally extractable, bitumen-like fraction that is chemically distinct from the remaining coal components. In lignite, several biomarker compounds were noticeable in the mobile phase components while bituminous coals contain various alkylsubstituted aromatic compounds in the mobile phase. Blind Canyon coal, which contains 11% resinite, exhibits mobile phase components believed to originate from terpenoid aromatization. Curie-point Py-LVMS results illustrate the importance of the oxidation status of coal for studying the mobile phase since mild air oxidation severely changes the structural characteristics of the thermally extractable mobile phase.

Effect of Mineral Matter on Coal Devolatilization Kinetics

Bae, I.; Maswadeh, W.; Yun, Y.; Meuzelaar, H.L.C. and DuBow, J.
Accepted for publication in the ACS National Meeting Preprints, Boston, Massechusetts,Spring, 1990. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Coal pyrolysis is a fundamental first step in combustion processes. Yet coals exhibit a wide variation in pyrolysis behaviors. The origins of these wide variations are, for a given set of experimental conditions, both structural and compositional in nature. Because of its thermochemical and catalytic properties, mineral matter plays an important role in both the thermodynamics (product mixes, activation energies) and kinetics of coal pyrolysis. The issue is further complicated by the manner in which mineral matter is distributed in various coals. While many classifications are possible, grouping into three classics is most common. These classes are: (1) discrete minerals such as clays, oxides (basic and acidic) and sulfides; (2) organometallic matter such as ion-exchangeable cations; and (3) dispersed trace elements and compounds. A considerable body of research exists for studying equilibrium and non-equilibrium effects of the various forms of coal minerals on coal combustion.

In the present paper the mineral matter effects on coal pyrolysis are being analyzed using an approach whereby observable spectroscopic (TG/MS) differences in the pyrolytic decomposition between fresh coal and demineralized coal are reconstructed from the sum of mineral matter effects on pyrolysis arising from adding back, singly and in pairs, individual minerals in various forms.

Mineral Matter Effects in Coal Pyrolysis

Bae, I.; Anani, M.; Maswadeh, W.; Yun, Y.; Meuzelaar, H.L.C. and DuBow, J.
199th ACS National Meeting, 35 (2), 489-493, Boston, Massachusetts, 1990. Funded by ACERC.

Coal pyrolysis is a fundamental first step in combustion processes. Yet coals exhibit a wide variation in pyrolysis behaviors. The origins of these wide variations are for a given set of experimental conditions, both structural and compositional in nature. Because of its thermochemical and catalytic properties, mineral matter plays an important role in both the thermodynamics (product mixes, activation energies) and kinetics of coal pyrolysis. The issue is further complicated by the manner in which mineral matter is distributed in various coals. While many classifications are possible, grouping into three classes is most common. These classes are: (1) discrete minerals such as clays, oxides (basic and acidic) and sulfides; (2) organometallic matter such as ion-exchangeable cations; and (3) dispersed trace elements and compounds. A considerable body of research exists for studying equilibrium and non-equilibrium effects of the various forms of coal minerals on coal combustion.

In the present paper the mineral matter effects on coal pyrolysis are being analyzed using an approach whereby observable spectroscopic (TG/MS) differences in the pyrolytic decomposition between fresh coal and demineralized coal are reconstructed from the sum of mineral matter effects on pyrolysis arising from adding back, singly, and in pairs, individual minerals in various forms.

Fast, Repetitive GC/MS Analysis of Thermally Desorbed Polycyclic Aromatic Hydrocarbons (PAHs) from Contaminated Soils

McClennen, W.H.; Arnold, N.S.; Roberts, K.A.; Meuzelaar, H.L.C.; Lighty, J.S. and Lindgren, E.R.
Combustion Science and Technology, 1990 (In press). Sponsored by Remediation Technology, Gas Research Institute, ACERC, Finnigan Corp. and IT Corporation.

A system for on-line analysis of organic vapors by short column gas chromatography/mass spectrometry (GC/MS) has been used to monitor products from a thermal soil desorption reactor. The system consists of a unique air-sampling inlet with a 1-meter long capillary column coupled directly to a modified Ion Trap Mass Spectrometer (Finnigan MAT) with demonstrated detection limits for alkylbenzenes in the low ppb range. In this work the mobile instrument is used for repetitive GC/MS and GC/MS (tandem MS) analysis at 30 to 60 sec intervals of PAH products from coal tar contaminated soils in a bed characterization reactor.

Results for napthalene through dibenzanthracenes are compared to conventional, more detailed GC/MS analyses of extracts from the soil before and after thermal treatment.

A combustion map of burnout values was made using the laboratory nozzle at an A/S of 0.7, swirl number of 1.5 and SR of 1.1.

Vapor Sampling Device for Direct, Short Column Gas Chromatography/Mass Spectrometry Analyses of Atmospheric Vapors

Arnold, N.S.; McClennen, W.H. and Meuzelaar, H.L.C.
Analytical Chemistry, 1990 (In press). Funded by ACERC.

A number of methods are currently used for atmospheric vapor and gas sampling with mass spectrometric detection and identification. Direct mass spectrometry (MS) sample introduction methods include fixed molecular tasks (1), atmospheric pressure ionization (2,3), trap and desorb (4), and membrane separation (5), while gas chromatography/mass spectrometry (GC/MS) methods employ trap and desorb (6), direct bubbler solvent injection (7,8), sample loops (9), and pressurized gas plug introduction (10). Approaches vary depending upon whether MS, tandem MS, or GC/MS analyses are desired. Direct MS and tandem MS analyses typically give quick response times and high repetition rates but are often sensitive to interference, including atmospheric constituents, while GC/MS analyses offer greater specificity but with typically lower results.

On-Line GC/MS Sampling of Exhaust Gas from a Rotary Kiln Simulator

Lighty, J.S.; Wagner, D.; Deng, X.-X.; Pershing, D.W.; McClennen, W.H.; Sheya, S.A.N.; Arnold, N.S. and Meuzelaar, H.L.C.
AWMA Specialty Conference on Waste Combustion in Boilers and Industrial Furnaces, Kansas City, MO, 1990. Funded by ACERC.

An on-line, short-column gas chromatography/mass spectrometry (GC/MS) system has been used to monitor the evolution of trace amounts of hydrocarbons evolving from a material which has been combusted in a rotary-kiln simulator. The system uses the isothermally heated, 1-m long transfer line of an Ion Trap Detector (ITD) as the gas chromatograph. The fused silica capillary normally used in the transfer line is replaced by a 1 m, 0 .15-mm inside diameter, 1.2 micron thick methyl silicone stationary phase (DB-1) GC column. Given the short column length and using a direct vapor sampling inlet, the exhaust gas can be sampled quickly, approximately every 10 s in these experiments. Since the column is isothermal, only a limited range of compounds can be analyzed for any given experiment.

Man-Portable Gas Chromatography/Ion Mobility Spectrometry System: GC/CAM

Meuzelaar, H.L.C.; Kim, M.-G.; Arnold, N.S.; Urban, D.T. ; Kalousek, P.; Snyder, A.P. and Eiceman, G.A.
US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense Research, Aberdeen Proving Grounds, Maryland, 1990. Funded by US Army Chemical Research Development and Engineering Center.

Currently there is widespread interest in extending the capabilities of ion mobility spectrometry (IMS) to various military as well as nonmilitary fields of application, including chemical demilitarization, treaty verification, drug enforcement, explosives detection and environmental monitoring. Characteristic features of IMS are high sensitivity, fast response, low weight, small size, low power requirements, and relatively low cost. An attractive approach is to add a front-end module capable of performing "transfer line gas chromatography" (TLGC). In its present form the TLGC/IMS system consists of a special automated air sampling valve, a short (1-2 m long) capillary GC column with isothermal oven, a Chemical Agent Monitor (CAM) and a small laptop PC. The IMS system is operated below ambient pressures.

Development and Testing of a Man-Portable Gas Chromatography/Mass Spectrometry System for Air Monitoring

Meuzelaar, H.L.C.; Urban, D.T. and Arnold, N.S.
Proceedings of the 1990 US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense, Aberdeen Proving Grounds, Maryland, 1990. Funded by Hewlett Packard Corp. and ACERC.

In situations involving special military or law enforcement operations, as well as industrial accidents or natural disaster, mobile laboratories may be of little use because of limited site access restrictions due to contamination or terrain constraints. Under such conditions man-portable analytical instruments may offer the only acceptable means of carrying out on-site analyses. The current prototype weighs approx 70-75 lbs and uses 150-200 W of battery power. The mass spectrometer and computer are carried in front of the operator by means of a shoulder harness whereas battery pack, carrier gas supply and roughing vacuum system are carried as a backpack. Air samples can be analyzed using a special automated air-sampling inlet. The man-portable GC/MS system is supported by a vehicle transportation "docking station."

Progress in CB Detection by Transfer Line GC/MS Using a Miniaturized Ion Trap Mass Spectrometer

Meuzelaar, H.L.C.; Arnold, N.S.; McClennen, W.H. and Snyder, A.P.
Proceedings of the 1989 US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense, 373-379, 1990. Funded by ACERC, US Army Chemical Research Development and Engineering Center, and Finnigan Corp.

A novel direct vapor-sampling inlet has been tested in combination with Transfer Line Gas Chromatography/Mass Spectrometry (TLGC/MS) using the MINITMASS (Miniaturized Ion Trap Mass Spectrometer) system developed at the University of Utah. Typically, 0.2-0.5 s wide air pulses are injected into the 1 m long transfer line at 15-60 s intervals. Even with relatively complex mixtures of vapors, e.g., produced by desorption and combustion of model compounds in a laboratory-scale fixed bed reactor, sufficient GC separation may be obtained to allow positive identification of minor reaction products by direct library search and matching procedures. Moreover, the high sensitivity of the MINITMASS allows tandem MS analysis of subpicogram quantities of selected model compounds.

1989

Effects of Weathering on the Molecular Structure of Coal

Jakab, E.; Yun, Y. and Meuzelaar, H.L.C.
Chemistry of Coal Weathering, Nelson, C.R., Editor, Chicago, Illinois, Elsevier Science Publishers, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates).

A variety of external oxidative stresses have potential for altering the molecular composition and structure of organic substances. Examples include molecular oxygen, gamma radiation, near-ultraviolet (near-UV) radiation, ozone, and peroxides. The aerial oxidation of organic substances under ambient conditions is a well-known chemical reaction of interest both from an academic and an industrial viewpoint. Numerous types of aerial oxidation processes, e.g., respiration, rancidity, etc., are of profound biological and technical importance. Freshly mined coal is a very air-sensitive material, and atmospheric oxygen is believed to be the principal chemical agent responsible for the progressive coal degradation phenomenon known as weathering. In this article, the types of compositional and structural changes that occur as a result of the reaction of coalified organic matter with molecular oxygen are described in terms of the time evolution of reactant, intermediate, and product structures.

A Flash Pyrolysis and Petrographic Study of Cutinite from the Indiana Paper Coal

Nip, M.; DeLeeuw, J.W.; Schenck, P.A.; Windig, W. and Meuzelaar, H.L.C.
Geochemica et Cosmochimica Acta, 53, 671-683, 1989. Funded by University of Utah.

Samples obtained from the high-volatile bituminous Indiana cuticle-rich and paper coals (Indiana, U.S.A.) were investigated by white light and blue light microscopy and by Curie point pyrolysis-mass spectrometry in combination with multivariate data analysis, Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. Samples obtained from several sites and of different degrees of weathering were analyzed. The maceral cutinite from the same samples was studied as well. The cutinite was concentrated by a standard palynological chemical oxidation technique as well as by density gradient centrifugation. The major constituent of the Indiana paper coal samples appeared to be a recently discovered non-saponifiable polymethylenic biopolymer, present in both recent and fossil plant cuticles. The maceral cutinite is almost exclusively made up of this highly resistant biopolymer. It is shown that upon severe natural weathering this biopolymer, because of its resistance against organic alteration and diagenesis, is relatively enriched and manifests itself in humic coals as the maceral cutinite.

Estimation of Coal Devolatilization Modeling Parameters from Thermogravimetric and Time-Resolved Soft Ionization Mass Spectrometric Data

Yun, Y.; Maswadeh, W.; Meuzelaar, H.L.C.; Simmleit, N. and Schulten, H.R.
ACS Preprint, Div. of Fuel Chemistry, Miami Beach, Florida, 34 (4), 1308-1316, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Nowadays it is widely recognized that the initial pyrolysis step in coal conversion processes has a profound effect on the yield and distribution of end products such as coal-derived liquids, gases, coke, or pollutant emissions. Two general approaches for modeling coal pyrolysis reactions can be distinguished, namely: (a) phenomenological modeling and (b) chemical modeling. The phenomenological modeling approach is useful in conversion processes such as high temperature gasification where detailed chemical information may be advantageous but is probably not indispensable. Other conversion processes, however, e.g., liquefaction and hydropyrolysis, may require more detailed chemical information to predict the distribution of final products. Whether pyrolysis ("devolatilization") models for pulverized coal combustion processes require detailed information on coal structure and reactivity or can be based primarily on a phenomenological approach is still a matter of considerable debate.

Heated screen pyrolysis techniques have been widely used to provide modeling parameters for phenomenological models based on the thermal behavior of light gas components detected by gas chromatography, mass spectrometry (MS) and other spectroscopic techniques. Due to limitations of the analytical techniques used, tar components are generally lumped into a single component.

Since time-resolved mass spectrometry (TR-MS) data can be used to analyze single mass profiles or mass spectra as a function of temperature, TR-MS data. Our estimations will be based on the chemical assignment of tar components observed in soft ionization mass spectra in combination with kinetic evaluation or temperature-resolved intensity profiles of single mass peaks and measured or simulated thermogravimetric weight loss curves.

The Mobile Phase in Coal Viewed From a Mass Spectrometric Perspective

Meuzelaar, H.L.C.; Yun, Y.; Simmleit, N. and Schulten, H.R.
ACS Preprint, Div. of Fuel Chemistry, Miami Beach, Florida, 34 (3), 693-701, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates).

In recent years few topics have generated a more spirited discussion among coal scientists than the issue of the putative binary (mobile + network) phase nature of coals. Initially based on NMR observations, the concept of a "mobile phase" in coal soon came to encompass a broad range of more or less readily extractable and/or distillable lower molecular weight (MW) components, variously referred to as "guest molecules", "clathrates" or simply, and perhaps most succinctly, "bitumen". None of these terms appears to be completely satisfactory. The concept of "mobility" in NMR spectroscopy is quite different from that in the field of separation science, where mobility generally requires a measurable degree of solubility and/or distillability in liquid or gaseous media, respectively. For example, polymethylene-like moieties, such as found in some coal components, are highly "mobile" in NMR terms, without necessarily being extractable by solvents or distillable by nondestructive heating. The term "guest molecules", originally introduced to indicate specifically labeled marker molecules used in NMR studies of coal, is equally unsatisfactory for mobile phase components indigenous to the coal itself. Also, there appears to be insufficient evidence for the presence of sizeable quantities of true "clathrates" to rule out other possibilities, e.g., strong noncovalent bonding rather than physical entrapment. Finally, completely equating the "mobile phase" with solvent (e.g. pyridine) extractable "bitumen" in coal ignores the potential presence of colloidal particulate matter in the pyridine extracts as well as possible solvent-induced scission of weak chemical bonds. Furthermore, the solvent-extractable fraction may well include macromolecular components, such as resinites.

Mass spectrometric observations have thus far played a rather limited role in the "mobile phase" discussions but are starting to shed some light on the key question: is there conclusive evidence for the presence of a chemically and/or physically distinct "mobile phase", as opposed to a continuum of possible molecular sizes and structures? In the context of the present discussion, the term "mobile phase" will be used to describe those components which can be thermally extracted ("distilled" "desorbed") under vacuum at temperatures below the thermal degradation range of the coal. The residue, designated as the nonmobile ("network") phase, is thermally degraded in the pyrolysis temperature range. Of course, the onset of pyrolysis may vary considerably, depending on heating rate, rank and coal type.

Laser Pyrolysis Mass Spectrometry of Single Levitated Coal Particles

Maswadeh, W.; Roberts, K.A.; McClennen, W.H.; Meuzelaar, H.L.C. and Arnold, N.S.
37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami Beach, Florida, 304-305, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates), US Department of Energy, and the State of Utah.

A laser pyrolysis mass spectrometry experiment was designed to study the devolatilization behavior of individual coal particles at high heating rates (104-106 K/s), characteristic of pulverized coal combustion reactors. The experimental set-up consists of an electrostatic particle levitation cell, also known as an "electrodynamic balance", a 50 W cw CO2 laser and a Finnigan-MAT ITMS system. The particle levitation cell was constructed by modifying a regular ion trap electrode assembly in such a way as to provide line-of-sight access to the center of the cell for the CO2 laser beam as well as for visual observation by means of a stereo microscope. Typical cell operating parameters for levitating a 120 mm dia. Spherocarb particle are: ring electrode 3000 V (60 Hz ac), upper end-cap +100 V dc, lower end-cap -100 V dc. The CO2 laser (Apollo 3050 OEM) is capable of electronic pulsed beam operation. The 8 mm dia. beam is split equally into 2 opposing beams focused at the center of the levitation cell (beam waist ca. 400 um, power density ca. 4-10 MW/m2), as a co-linear parfocal HeNe laser beam permits positioning the levitated particle in the optical and electrical center of the cell. Two IR detectors measure the integrated pulse and time-resolved pulse energy.

A heated transfer line column (2m x .18 mm DB5) equipped with a special air sampling inlet enables intermittent sampling of volatiles from the center of the levitation cell into the ITMS vacuum system. Feasibility studies were performed on 120-150 mm Spherocarb particles impregnated with an alkylnaphthalenes mixture and heated with a single 10 ms CO2 laser pulse. Ample signal intensities were obtained with the first laser pulse to permit the recording of "transfer line" GC/MS profiles. By contrast, the second laser pulse produced <10% of the volatiles observed from the first pulse, thereby demonstrating nearly complete devolatilization of the impregnated particle by a single laser pulse.

Finally, a series of experiments was performed with actual coal particles in the 100-130 mm size range, prepared by careful sieving of two coals from the Argonne National Laboratory Premium Coal Sample bank, namely a Pittsburgh #8 seam (Illinois) coal and a Blind Canyon seam (Utah) coal of comparable rank. From previous studies of Pitt. #8 coal using time-resolved Curie-point pyrolysis, pyrolysis temperatures necessary to produce these phenolic building blocks at heating rates of 105 K/sec are estimated to be ca. 900 K. Of course, kinetic parameters obtained at the much lower heating rates of the Curie-point pyrolysis MS experiment (approx. 102 K/s) may only be extrapolated to the laser pyrolysis experiment if the underlying reaction mechanisms are comparable. Evidence supporting this assumption is presented showing similar C1 and C2-alkyl phenol profiles for the Pitt. #8 coal obtained by Curie-point pyrolysis GC/MS using a 15 m fused silica capillary with temperature programming.

Development of a Mobile Ion Trap Mass Spectrometer for Environmental Monitoring

Meuzelaar, H.L.C.; McClennen, W.H.; Arnold, N.S.; Maswadeh, W.; Reynolds, T.K.; Urban, D.T. and Jones, P.R.
Proc. 37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami Beach, Florida, 1424-1426, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Center and Finnigan-MAT Corp.

The objective of the work reported here is to develop a compact, mobile mass spectrometer with EI, CI and MSn capabilities. Moreover, the mobile MS system should be capable of analyzing gases, vapors and aerosols in air at low ppb levels while allowing positive identification of individual components in complex mixtures. In view of the size and weight restrictions inherent in the mobility requirement, a special miniaturized version of the Finnigan MAT Ion Trap Mass Spectrometer (ITMS?) was constructed in close collaboration with the manufacturer. This MINITMASS Miniaturized Ion Trap Mass Spectrometer) system is equipped with automatic gain control, automatic reaction control, selective mass storage and axial modulation options, in addition to the required EI/CI and MSn operating modes. The 2x2x2 ft MINITMASS module is mounted within a 6 ft high mobile rack together with all gas supplies, pumps, inlet controls and a PC 80386 workstation. The entire system requires approx. 1000 W of ac power. A 6x7x8 ft, self-contained mobile laboratory module, which fits on a standard 3/4 ton pick-up truck, enables operation of the MINITMASS in remote locations and rugged terrain. Also, the MINITMASS system can be remotely controlled from a distance up to several miles using a second PC workstation, and Carbon Copy© software. A direct air-sampling inlet enables repetitive collection of 10-50 microliter air samples at 15-60 sec intervals. Use of "transfer line chromatography" provides additional resolution and specificity for complex mixtures. Minimum detectable levels of gases and vapors in air are in the low to medium ppb range without the use of concentration devices. Alternatively, a special automated inlet enables electrostatic precipitation of air particulate matter on a ferromagnetic filament with subsequent analysis by Curie-point pyrolysis (GC)/MSn. The system has been successfully operated in the desert (at temperatures up to 100 F), as well as under a variety of indoor conditions, e.g., for monitoring laboratory-scale combustion reactors.

Direct On-Site Vapor Monitoring by Transfer Line GC/MS

Arnold, N.S.; Roberts, K.A.; McClennen, W.H. and Meuzelaar, H.L.C.
Proc. 37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami Beach, Florida, 1424-1426, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Center and Finnigan-MAT Corp.

A direct atmospheric vapor sampling inlet has been used for on-line monitoring of vapors in laboratory scale reactors. The inlet consists of three concentric tubes with appropriate flow control plumbing and electronics. This inlet provides for direct introduction of a pulse of air (.5 to 2 s) into a short (1 m) coated fused silica capillary column enclosed in the heated transfer line housing of a Finnigan-MAT ITD. Effluent from the column emerges directly into the ion trap. Data presented here were obtained by sampling from a bed-characterization reactor (for waste disposal studies) using the MINITMASS, a modified mobile Ion Trap Mass Spectrometer. (Alternate sampling environments have included a coal combustor, an open air chemical release, a micro-scale laser pyrolysis chamber, and in-building ambient atmospheres.) Vapor samples were obtained repetitively at 60 s intervals, allowing for an isothermal GC separation of various components. A ~1.5 s vapor sample allowed up to 100 ul (@STP) of reactor atmosphere to enter the transfer line for chromatographic separation. A .18 mm ID transfer line with a .4 um DB-5 coating (J+W Scientific) was operated isothermally at either 25º, 80º or 125ºC. Carrier gas (helium) velocity was -2.7 m/s (at column temp=25ºC and 4400 ft elevation). All analyses were performed using electron impact ionization. Detection limits have been established near the 1 ppb level for various substituted aromatic compounds using this (MINITMASS) system and taking advantage of the Axial Modulation* and Selective Mass Storage* features to improve sensitivity. Estimations of concentration in this presentation are provided from the calibration data obtained on toluene, ethylbenzene, o-, m-, and p-xylene and general sensitivity characteristics of ion trap mass spectrometers for the compounds of interest. In the present analyses, halogen-, nitrogen- and oxygen-substituted aromatics have been detected at <100 ppb. Various column temperatures allowed for analysis of compounds with atmospheric boiling points from 80ºC (benzene) to 350ºC (anthracene) present in reactor vapors. To date, test analyses of high boiling compounds than these have required the reactor be run under nitrogen to prevent rapid column degradation, though compounds as involatile as dibenzanthracenes (bp 550ºC) have been detected under test conditions.

A Mobile, Tandem Ion Trap Mass Spectrometer System for Environmental Monitoring of Vapors

Arnold, N.S.; McClennen, W.H.; Maswadeh, W.; Urban, D.T.; Reynolds, T.K.; Jones, P.R. and Meuzelaar, H.L.C.
Proceedings of the 1989 U.S. Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense Research, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Center, Geocenter, Inc. and Finnigan-MAT Corp.

A fieldable, Miniaturized Ion Trap Mass Spectrometer (MINITMASS) was constructed for tandem mass spectrometry of environmental vapors. Furthermore, a vapor sampling inlet for transfer line gas chromatography/mass spectrometry was developed which permits direct on-column introduction of atmospheric vapor samples. The transfer line gas chromatography/tandem mass spectrometry combination provided for direct introduction of complex vapor samples with short overall analysis times for on-line monitoring of changing environmental conditions. Work to date has shown the capability for low ppb analysis of substituted aromatic hydrocarbons, corresponding to subpicogram quantities per compound, in MS as well as MS/MS mode.

On-Site Transfer Line GC/MSn Analysis of Environmental Vapors Using a Modified Ion Trap Mass Spectrometer

Arnold, N.S.; McClennen, W.H. and Meuzelaar, H.L.C.
Preprints of Papers Presented at the 198th ACS National Meeting, 29 (2),Miami Beach, Florida, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Research Center and Finnigan-MAT Corp.

An air-sampling inlet has been developed for on-column injection of atmospheric vapor samples using transfer line GC/MS analysis. Repetitive sampling at 15 to 60 sec intervals provides for short GC separations of the individual components. On-site GC/MSn analyses have been performed using a modified mobile ion trap mass spectrometer. Sites sampled thus far include a laboratory scale coal combustor, a high temperature soil desorber for hazardous waste disposal studies, an open-air chemical release and in-building ambient atmospheres.

Current detection limits are on the order of 1 ppb for selected compounds. Compounds with boiling points greater than 80ºC (e.g., benzene) can be readily separated with a 1 m DB-5 coated fused silica column. Analyses reported here are primarily aimed at aromatics through benzopyrene including nitrogen-, oxygen- and halogen-substituted compounds.

Progress in CB Detection by Transfer Line GC/MSn Using a Miniaturized Ion Trap Mass Spectrometer

Meuzelaar, H.L.C.; Arnold, N.S.; McClennen, W.H. and Snyder, A.P.
Proceedings of the 1989 US Army Chemical Research Development and Engineering Center Scientific Conference on Chemical Defense Research, 1989. Funded by ACERC (National Science Foundation Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Center and Finnigan-MAT Corp.

A novel direct vapor-sampling inlet has been tested in combination with Transfer line Gas Chromatography/Mass spectrometry (TLGC/MSn) using the MINITMASS (Miniaturized Ion Trap Mass Spectrometer) system developed at the University of Utah. Typically, 0.2-0.5 s wide air pulses are injected into the 1 m long transfer line at 15-60 s intervals. Even with relatively complex mixtures of vapors, e.g., produced by desorption and combustion of model compounds in a laboratory-scale fixed bed reactor, sufficient GC separation may be obtained to allow positive identification of minor reaction products by direct library search and matching procedures. Moreover, the high sensitivity of the MINITMASS allows tandem MS analysis of subpicogram quantities of selected model compounds.

Development and Testing of a Mobile Tandem Mass Spectrometer for Monitoring Gases, Vapors, and Aerosols

Meuzelaar, H.L.C.; Arnold, N.S.; McClennen, W.H. and Maswadeh, W.
Conference on Environmental Chemistry, Jeckyll Island, Georgia, 1989. Funded by ACERC (National Science Foundation Associates and Affiliates), the State of Utah, US Department of Energy, the Department of Defense Chemical Research Development and Engineering Center, Geocenter, Inc. and Finnigan-MAT Corp.

Recent advances in Ion Trap/Mass Spectrometry (ITMS) technology now enable the assembly of compact ITMS systems with Chemical Ionization (CI) as well as tandem MS (MSn) capabilities. In combination with the proven high sensitivity (full spectra have been recorded on less than 1 pg of sample) and the favorable vacuum characteristics, ITMS devices appear especially well suited for a variety of environmental monitoring tasks.

Based on these assessments, we undertook the development of a mobile Miniaturized Ion Trap Mass Spectrometer (MINITMASS) equipped with specialized air sampling inlets for gases/vapors as well as for aerosols. Both inlet systems employ the so-called transfer line chromatography (TLGC) approach in order to increase specificity and minimize exposure of transfer line, ion source and electron multiplier to oxygen.

Gases and vapors are sampled as 1-2 sec wide air "pulses" at 15-60 second intervals depending on the degree of chromatographic separation required. Minimum detectable concentration levels were found in the low to medium ppb range. The aerosol inlet uses electrostatic precipitation of aerosol particles (0.5-5 um range) on a ferromagnetic filament. After a preselected collection period (e.g., 1-10 minutes) the filament is automatically inserted into a Curie-point pyrolysis reactor with subsequent production of the pyrolysis GC/MS patterns of the collected aerosol particles.

Thus far, the system has been tested with synthetic polymers, biopolymers and bacterial spores.

Monitoring the Evolution of Organic Compounds from the Thermal Treatment of Contaminated Soil Samples Using Short Column GC/MS

McClennen, W.H.; Arnold, N.S.; Lighty, J.S.; Eddings, E.G.; Lindgren, E.R.; Roberts, K.A. and Meuzelaar, H.L.C.
Preprints of Papers Presented at the 198th ACS National Meeting, 34 (3), Miami Beach, Florida, 1989. Funded by the Gas Research Institute, Dave Linz, Project Manager, ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, and US Department of Energy.

Incineration is an effective technology for the remediation of organic chemical contaminated wastes. For solid wastes, such as contaminated soils, processes involving separate stages of a primary desorber and secondary afterburner are particularly useful. The desorption stage is currently being modeled using a particle-characterization reactor (PCR, 0-500 g capacity), a bed-characterization reactor (BCR, 0.5-5 kg), and a rotary kiln simulator (2-15 kg) to study fundamental processes such as mass transfer, heat transfer, and volatilization of contaminants. This paper describes the analytical methods and preliminary results from monitoring the evolution of organic compounds in these and smaller reactors.

The samples are soil contaminated with a broad range of polynuclear aromatic (PNA) hydrocarbons such as those derived from coal tars. The analytical methods primarily involve mass spectrometry (MS) with a variety of sample introduction techniques. The on-going analyses include solvent and thermal extractions of soil before and after various thermal treatments as well as on-line monitoring of vapors during desorption.

Fast, Repetitive GC/MS Analysis of Thermally Desorbed Polycyclic Aromatic Hydrocarbons (PAHs) from Contaminated Soils

McClennen, W.H.; Arnold, N.S.; Roberts, K.A.; Meuzelaar, H.L.C.; Lighty, J.S. and Lindgren, E.R.
1st International Congress on Toxic Combustion, 1989. Funded by Remediation Technologies, the Gas Research Institute, ACERC (National Science Foundation and Associates and Affiliates), the State of Utah, and US Department of Energy.

A system for on-line analysis of organic vapors by short column gas chromatography/mass spectrometry (CG/MS) has been used to monitor products from a thermal soil desorption reactor. The system consists of a unique air-sampling inlet with a 1 meter long capillary column coupled directly to a modified Ion Trap Mass Spectrometer (Finnigan MAT) with demonstrated detection limits for alkylbenzenes in the low ppb range. In this work the mobile instrument is used for repetitive GC/MS and GC/MSn (tandem MS) analysis at 30 to 60 sec intervals of PAH products from coal tar contaminated soils in a bed characterization reactor.

Results for naphthalene through dibenzanthracenes are compared to conventional, more detailed GC/MS analyses of extracts from the soil before and after thermal treatment.

1988-1986

Off-Line Process Monitoring of Coal-Derived Liquid Fuels by Computer Assisted Low Mass Spectrometry

Taghizadeh, K.; Davis, B.H.; Windig, W. and Meuzelaar, H.L.C.
Fossil Fuel Analysis by Mass Spectrometry, 1988, T.A. Milne, (ed.), in press. Funded by Commonwealth of Kentucky, Kentucky Energy Cabinet, US Department of Energy and Consortium For Fossil Fuel Liquefaction Science.

Compositional changes of Coal-Derived Liquids (CDL's) during hydrotreatment on fixed bed catalysts can be investigated by Low Voltage (12 eV) MS in combination with multivariate analysis without chromatographic preseparation. Low voltage (12 eV) MS data were obtained and compared under two inlet conditions; MS inlet (1) at ambient temperatures and (2) preheated to about 200ºC. The major trend found in both data sets by Factor analysis was the hydrotreatment effect, namely hydroaromatic (hydrotreater product) vs. aromatic (hydrotreater feed) compounds. A second "time + temperature" trend which reflected the aging of the catalyst as well as the temperature of the hydrotreater reactor was only obtained under ambient inlet temperature conditions. Numerically extracted spectra along the second trend show that more low molecular weight components were found early in the process and also at lower temperatures, whereas more of the higher molecular weight components, primarily alkyl substituted polynuclear aromatics, were obtained later in the process at higher temperatures of the hydrotreater.

A supercritical fluid chromatographic system was constructed to provide separations and fraction collection on a semipreparative scale. Columns packed with silica materials of intermediate particle sizes (30-70 mm) were used to allow dynamic pressure programming with minimum pressure drop of the CO2 mobile phase along the length of the column. A variety of complex coal- and petroleum-derived polycyclic aromatic compound mixtures were fractionated according to the number of aromatic rings using columns packed with an NH2- modified stationary phase bonded on silica particles. The CO2 mobile phase was programmed with an alternating series of linear pressure ramps and isobaric intervals to effect even peak spacing and near base line resolution of compounds of differing ring number in a coal tar. A solvent refined coal heavy distillate and a crude oil were similarly fractionated. Effluents were monitored with an ultraviolet spectrophotometer at 254 nm and a flame ionization detector while fractions were collected in pressurized vessels for subsequent analysis by capillary gas chromatography. Sample capacities of up to 20 mg were possible with this system.

Pyrolysis Short-Column GC/MS Using the Ion Trap Detector (ITD) and Ion Trap Mass Spectrometer (ITMS)

Richards, J.M.; McClennen, W.H.; Bunger, J.A. and Meuzelaar, H.L.C.
Finnigan Application Note, (214), 1988. Funded by Finnigan MAT.

The results in this report show the capabilities of a short column equipped with a flash pyrolysis/evaporation inlet and interfaced directly to an ITD. The system has proven to be capable of rapid analysis of complex natural and synthetic materials, with relatively little loss in resolution relative to longer columns.

Investigation of Structure/Property Relationships of Selected C5 to C10 Hydrocarbons Using Canonical Correlation Analysis of Multisource Data

Hoesterey, B.L.; Meuzelaar, H.L.C. and Pugmire, R.J.
Submitted to Anal. Chem., 1988. 28 pgs. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Twelve physico-chemical and thermodynamic properties including molecular weight, boiling point, flash point, density, refractive index, volumetric, gravimetric, and molar heats of combustion, atomic H/C, carbon number, hydrogen number and the fuel-related threshold sooting index for 47 C5 to C10 hydrocarbons were subjected to factor analysis. Two factors with eigenvalues greater than 1.0 were found, accounting for 95% of the variance. The major groups of variables were interpreted as arising from either molecular size (boiling point, flash point, molar heat of combustion, molecular weight and carbon number) or degree of unsaturation (density, refractive index, volumetric heat of combustion, threshold sooting index, H/C and gravimetric heat of combustion). When three factors from the physicochemical and thermodynamic properties factor space were used for canonical correlation analysis with the Wiener topological index, molecular size related papers were found to correlate with it. Canonical correlation analysis of the properties factor space with mass spectrometry/Kavats retention index data showed that characteristic mass spectral variables correlated closely with the degree of unsaturation by differentiating aliphatic from aromatic compounds. The Kovats retention index variable, not unexpectedly, modeled molecular size related parameters such as carbon number.

Effects of Low Temperature Air Oxidation (Weathering) Reactions on the Pyrolysis of Mass Spectra of US Coals

Jakab, E.; Hoesterey, B.L.; Windig, W.; Gill, G.R. and Meuzelaar, H.L.C.
Fuel, 67, (1), 73-79, 1988. 6 pgs. Funded by US Department of Energy and Utah Power and Light.

Two high volatile bituminous coals (Upper Freeport and Hiawatha seams), a subbituminous coal (Adaville seam) were used to investigate the effect of low temperature air oxidation ("weathering") on the yield and composition of vacuum pyrolysis products. Fresh coal samples were exposed to air at 80º and 100ºC for up to 10 days under controlled laboratory conditions. Curie-point pyrolysis mass spectrometry combined with computerized data analysis was applied to study the weathering induced changes in a series of samples weathered for various lengths of time. It was found that the abundance of small oxygen-containing molecules such as carbon monoxide, carbon dioxide and aliphatic carboxylic acids increased in the pyrolysate of all samples, whereas phenols and dihydroxybenzenes showed decreased yields, especially in the two lowest rank coals. Besides phenols, alkylnaphthalenes and alkyltetralins showed decreased abundances in the pyrolysis mass spectra of the two high volatile bituminous coals. An attempt is made to explain the difference in pyrolysis patterns observed before and after weathering experiments in terms of underlying structural changes.

Comparison of Low Voltage and Field Ionization Mass Spectra of Coal Derived Liquids from the Wilsonville Plant

Taghizadeh, K.; Hardy, R.H.; Davis, B.H. and Meuzelaar, H.L.C.
Submitted to Analytical Chemistry, 1988. Funded by Commonwealth of Kentucky, Kentucky Energy Cabinet, and US Department of Energy.

Low voltage (LV) and field ionization (FI) mass spectral of coal-derived liquids (CDL) before and after hydrotreatment from the Wilsonville Coal liquefaction pilot plant were compared. LV-MS (12eV) analysis of Wilsonville CDL'S before and after hydrotreatment produces very similar spectral patterns as obtained by FI-MS. This is especially true for the more highly aromatic hydrotreater feed samples since hydroaromatic compounds tend to fragment more under LV-MS conditions. Canonical variate analysis confirms that the mass spectral patterns produced by both techniques are highly correlated with the exception of the higher mass range (above m/z 300) that appears to be underrepresented in the LV-MS patterns, primarily as a result of lower inlet temperatures. Furthermore, in spite of the highly complex nature of the original spectral profiles, use of multivariate statistical analysis techniques, such as factor analysis and canonical correlation analysis, enables "numerical extraction" of simplified spectral patterns which can be tentatively interpreted in terms of chemical components or compound series.

Time-Resolved Pyrolysis Mass Spectrometry of Coal: A New Tool for Mechanistic and Kinetic Studies

Chakravarty, T.; Meuzelaar, H.L.C.; Windig, W. and Hill, G.R.
Energy & Fuel, 2, 400-405, 1988. 5 pgs. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Most coal devolatilization studies so far have focused on the determination of reaction rates for reactions occurring under widely different conditions encountered in liquefaction, gasification, coking or combustion processes. Published rates on more or less comparable coals may differ by several orders of magnitude, especially when obtained at high temperatures (>1000 K) and/or high heating rates (10²-105 K/s).

At the present state-of-the-art in coal devolatilization research, more emphasis should perhaps be placed on elucidating the mechanisms of the chemical reactions underlying the observed phenomena. When studying thermal conversion reactions in coal it seems correct to concentrate first on the so-called "primary" reactions before attempting to elucidate the many possible secondary reaction pathways. This is especially true since most secondary reaction pathways are strongly influenced by reactor design and experimental conditions.

The devolatilization behavior of coal will be determined primarily by the chemical composition of coal and secondly by the experimental conditions. Under properly designed vacuum micropyrolysis experiments working with sufficiently small particles (<50 mm diameter), it is possible to avoid mass and heat transport limitations and minimize the secondary reactions. Using unoxidized or well preserved coal samples, the chemical composition can be well defined and possibly characterized by major factors such as rank and depositional environment. Recent advances in pyrolysis mass spectrometry (Py-MS), viz, time-resolved Py-MS (TR Py-MS), along with multivariate analysis techniques enable extraction of underlying chemical components from a single experiment, thus reducing the uncertainty due to varying reactions conditions in different experiments. This paper demonstrates the feasibility of obtaining valuable mechanistic and kinetic data using microgram amounts of carefully selected coal samples under properly designed reaction conditions using TR Py-MS techniques in combination with advanced multivariate data analysis methods.

An Integrated Spectroscopic Approach to the Chemical Characterization of Pyrolysis Oils

Hoesterey, B.L.; Windig, W.; Meuzelaar, H.L.C.; Eyring, E.M.; Grant, D.M. and Pugmire, R.J.
Processing of Pyrolysis Oils, 1988, E.J., Soltes (ed.) ACS Symp. Series, in press. Funded by Consortium for Fossil Fuel Liquefaction Science and US Department of Energy.

The hydrocarbon ("oil") fraction of a coal pyrolysis tar prepared by open-column liquid chromatography (LC) was separated into l6 subfractions by a second LC procedure. Low voltage mass spectrometry (MS), infrared spectroscopy (1R), and proton (PMR) as well as carbon-13 nuclear magnetic resonance spectrometry (CMR) were performed on the first 13 subfractions. Computerized multivariate analysis procedures such as factor analysis followed by canonical correlation techniques were used to extract the overlapping information from the analytical data. Subsequent evaluation of the integrated analytical data revealed chemical information that could not have been obtained readily from the individual spectroscopic techniques. The approach described is generally applicable to multisource analytical data on pyrolysis oils and other complex mixtures.

Simultaneous Thermogravimetric and Mass Spectrometric Observations on Vacuum Pyrolysis of Argonne PCSP Coals

Yun, Y. and Meuzelaar, H.L.C.
ACS Preprint, 1988, Los Angeles. Funded by ACERC (National Science Foundation and Associates and Affiliates).

The most serious limitations of many coal gasification and liquefaction models are due to the lack of char and total volatiles yield data, of accurate kinetic parameters, and of reliable data on the composition of the total volatiles in the initial devolatilization step. Consequently, a vacuum thermogravimetry/mass spectrometry (TG/MS) system of a Mettler TA1 Thermoanalyzer and a Finnigan MAT 32000 quadrupole mass filter was built to obtain accurate quantitative and qualitative data on coal devolatilization processes at heating rates in the 10-2-10-1 K/s range. Hundreds of mass spectra can be obtained during a single TG run, thereby providing detailed information about the concentration of various devolatilization products as a function of temperature while continuously recording the sample weight loss. Moreover, factor-analysis-based methods enable deconvolution of overlapping trends and numerical extraction of chemical component spectra. TG/MS results on four Argonne PSCP coals are discussed.

Prediction of the Composition of Coal Tars from the Pyrolysis Mass Spectra of the Parent Coals Using Canonical Correlation Techniques

Chakravarty, T.; Meuzelaar, H.L.C.; Jones, P.R. and Khan, M.R.
ACS Preprints, 33, (2), 235-241, 1988. Toronto, CA. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Numerical comparison of compositional data on coals and their corresponding pyrolysis tars enables the construction of empirical mathematical models to predict liquid yield and composition from spectroscopic data of the parent coal. This approach was successful when using spectroscopic methods combined with vacuum micropyrolysis techniques, viz. Curie-point pyrolysis mass spectrometry. Nineteen US coals and the corresponding pyrolysis liquids prepared by the SHRODR method were analyzed by means of Curie-point pyrolysis low voltage MS. The pyrolysis mass spectra of the coals were composed of mainly primary pyrolysis products typical of vacuum micropyrolysis and were substantially different from the low voltage mass spectra of the corresponding SHRODR tars produced under batch autoclave conditions which promote the formation of secondary pyrolysis products. Nevertheless, it proved feasible to model and predict SHRODR tar spectra from the vacuum micropyrolysis spectra of the coals with a high degree of precision by means of factor analysis-based canonical correlation methods.

Numerical Comparisons Between the Pyrolysis Mass Spectra of Twelve US Coals and Their Relative Solubility in Microbial Cultures or Alkaline Buffer

Yeh, G.C.; Ward, B.; Quigley, D.R.; Crawford, D.L. and Meuzelaar, H.L.C.
ACS Preprints, 1988, Los Angeles, CA, in press. Funded by US Department of Energy.

Curie-point pyrolysis mass spectra of twelve low-rank US coals with various degrees of natural weathering were correlated with the results of biosolubility screening tests involving six selected microorganisms as well as with a specially designed alkaline solubility test. The main objectives of this study were to determine which mass spectral characteristics, if any correlated with the degree of biosolubilization trends, a main trend which correlates positively with the presence of severely oxidized aromatic moities in the coal and apparently enables biosolubilization by all six microorganisms, and a second trend which correlates with relatively high concentrations of acid components and enables biosolubilization by only two or three of the organisms. The chemical and biological significance of these trends is not yet completely understood. Finally, in agreement with previous reports a strong positive correlation was observed between biosolubility and alkaline solubility.

The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam

Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H. and Karas, J.
Submitted to Coal Geology, 1987. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Although the maceral resinite occurs in most US coals, it is particularly abundant in the coal seams of central Utah. The high resinite content of the coals of central Utah has long been known and commercially exploited but little work has been reported on the elucidation of the chemical composition of this material. Indeed, there is little such information on the resinite of any coal. The resinite occurrences have been described by Spieker and Baker, Tomlinson, Theissen and Sprunk, and Buranek and Crawford. An unusual feature of the coal seams in Utah is that most of the resinite occurs in a secondary manner as cleat, fissure, or other void fillings. Similar occurrences have been reported in British coals by Jones and Murchison and Murchison and Jones. They concluded that the metamorphic effects of coalification in the bituminous rank range caused the resinite to be gently mobilized without the more severe manifestations of metamorphism such as vesiculation or increased refectance. Teichmuller, observed that secondary resinite (exudatinite) seemed to be exuded from other coal macerals during coalification in the lower bituminous range.

Entrained gasification tests with a Utah high-volatile bituminous coal were performed at atmospheric pressure to assess the influence of particle size, coal feed rate, steam-coal ratio and oxygen-coal ratio. Independent argon-carbon balanced and ash balance methods were used to evaluate carbon conversion, with good agreement observed between the methods. A higher O2-coal ratio for finer particles increased the carbon conversion. Carbon conversion and hydrogen formation showed little dependence on the amount of steam injected in the secondary stream, indicating minimal steam-coal reaction. When the coal feed rate was varied from 23 to 27 kgh-1, a small increase in carbon conversion was observed with no significant change in the gas composition.

Determination of Fractional Concentrations and Exact Component Spectra by Factor Analysis of Pyrolysis Mass Spectra of Mixtures

Windig, W.; McClennen, W.H. and Meuzelaar, H.L.C.
Chemometrics and Intelligent Laboratory Systems, 1, 151-165, 1987. 14 pgs. Funded by US Air Force, Army Research Office and BF Goodrich.

Factor analysis of the "correlation around the origin" matrix as applied to (pyrolysis-) mass spectrometry data is described. This approach makes it possible to calculate the spectra of pure components from a data set of mixtures in which these pure components are not present. Further, the fractional concentrations of the components in the mixtures can be calculated. Examples are given of results obtained on data sets consisting of (pyrolysis) mass spectra from biopolymers, jet fuels and technical polymers.

Prediction and Modeling of Coal Conversion Reactions by Pyrolysis Mass Spectrometry and Multivariate Statistical Analysis

Meuzelaar, H.L.C.; Hoesterey, B.L.; Windig, W. and Hill, G.R.
Fuel Processing Technology, l5, 59-70, 1987. 11 pgs. Funded by Electric Power Research Institute and US Department of Energy.

Report on the use of Curie-point pyrolysis MS as a microscale modeling technique for the conversion of four Western US coals into pyrolytic tars and for the production of SO2 during the combustion of l6 Gulf Province lignites.

Self-Modeling Curve Resolution by Factor Analysis of a Continuous Series of Pyrolysis Mass Spectra

Windig, W.; Jakab, E.; Richards, J.M. and Meuzelaar, H.L.C.
Anal. Chem. 59, 317-323, 1987. 6 pgs. Funded by The Center for Micro Analysis.

A self-modeling technique for curve resolution of overlapping processes is presented. This method uses factor analysis combined with the variance diagram technique to resolve the total ion current (TIC) curves from time-resolved pyrolysis mass spectrometry data into chemical component curves and their spectra. Examples are presented of time-resolved pyrolysis mass spectrometry data from a biopolymer mixture (deoxyribonucleic acid, bovine serum albumin, and glycogen), Douglas fir wood, and a rubber copolymer. The analysis of each of these samples resulted in the resolution of the TIC's into chemical component curves. The spectra corresponding to the chemical components were clearly similar to reference spectra.

Characterization of US Lignites by Pyrolysis Mass Spectrometry and Multivariate Analysis

Metcalf, G.S.; Windig, W.; Gill, G.R. and Meuzelaar, H.L.C.
International Journal of Coal Geology, 7, 245-268, 1987. 23 pgs. Funded by US Department of Energy, Phillips Petroleum, and State of Utah.

Sixteen Texas (Gulf Province) lignite samples and six Montana and Wyoming (Northern Plains province) lignite samples were obtained from the Penn state coal sample collection and analyzed in triplicate by pyrolysis mass spectrometrey (Py-MS) using Curie-point pyrolysis (equilibrium temp. 610ºC) in combination with low voltage (12 eV) electron ionization. The spectra obtained were evaluated by means of factor analysis, followed by discriminant analysis using only factors with eigenvalue >= 1 and regarding each set of triplicate spectra as a separate category. The discriminant analysis results showed a definite separation between lignites from the two provinces as well as some clustering of samples from the same seam field or region. Six additional lignite samples obtained from an independent source and representing other regions of the Gulf province were found to cluster with the Texas lignite samples when treated as "unknowns" in the discriminant analysis procedure.

Chemical interpretation of the spectral differences underlying the clustering behavior of the lignite samples in the discriminant analysis procedure was attempted using a newly developed, unsupervised numerical extraction method for chemical components in complex spectra. This procedure the Variance Diagram (VARDIA) technique revealed the presence of six major chemical component axes. Examination of the spectral patterns corresponding to these component axes showed a softwood lignin-like component (high in Northern Plains lignites) and an aliphatic (algal?) hydrocarbon component (high in Gulf lignites) to be primarily responsible for the differences between the two provinces. In addition, two biomarker patterns, namely a terpenoid resin-like component and an unknown component, were shown to be highly characteristic for the Northern Plains and Gulf Province lignites respectively. Two other component axes were found to consist largely of sulfur-containing ion series, one of which appeared to represent an obvious marine influence on the South Texas region of the Gulf province.

Furthermore, a set of seventeen conventional coal parameters, including petrographic, ultimate and proximate analysis data as well as sulfur content, calorific value and vitrinite reflectance, obtained from the Penn State coal data bank on all twenty-two lignite samples, was also submitted to factor analysis. Comparison of the scores of the first two factors from this set with the scores of the first two discriminant functions of the Py-MS data set revealed an overall similarity in clustering behavior of the lignite samples from the two provinces. Subsequently, canonical variate analysis was used to rotate both the conventional and Py-MS data sets to a common set of vectors describing and correlating ("overlapping") portions of both data sets. Examination of the first two pairs of canonical variate functions revealed strong correlations between the conventional data and the Py-MS data, e.g., with regard to aliphatic vs. aromatic or hydrocarbon tendencies, as well as sulfur containing moieties. This enabled a final, tentative synthesis of all the lignite data into several highly simplified schemes relating compositional aspects to depositional environments.

Effect of Low Temperature Oxidation on Time-Resolved Pyrolysis Mass Spectra of Hiawatha Coal

Jakab, E.; Windig, W. and Meuzelaar, H.L.C.
Energy and Fuels, 1, 161-167, 1987. 6 pgs. Funded by US Department of Energy and Utah Power and Light.

Time-resolved Curie-point pyrolysis mass spectrometry (Py-MS) is demonstrated to be a promising new method for studying thermal decomposition reactions in coal. The effect of low temperature oxidation ("weathering") on the structural characteristics of a high volatile bituminous Hiawatha coal was investigated. Microgram amounts of coal were heated to 610ºC at a rate of 10²K/s. As many as 40 low voltage mass spectra were obtained within 8 s and subsequently evaluated by means of factor analysis. The results were compared with those of conventional time-integrated Curie-point Py-MS as well as combined thermogravimetry/mass spectrometry.

It was found that the decomposition of Hiawatha coal takes place in several stages while heating the samples up to 610ºC. The evaporation of "trapped" compounds and the decomposition of labile functional groups around 300ºC represent the first steps followed by the rapid decomposition of the char residue.

The weathered coal sample has undergone substantial changes as reflected by the pyrolysis results. The amount of "trapped" volatile components (primarily alkylnaphthalenes) is markedly decreased in the weathered coal accompanied by a decrease in the abundance of hydroxyaromatic compound series (primarily alkylphenols). Furthermore, the yield of short chain aliphatic carboxylic and carbonylic moieties is strongly increased.

Attempted Development of a "Weathering Index" for Argonne PCSP Coals

Yun, Y.; Hoesterey, B.L.; Meuzelaar, H.L.C. and Hill, G.R.
ACS Preprints, 32, 4, 1987, New Orleans. Funded by US Department of Energy.

In order to develop a reliable, simple procedure for determining the oxidation status ("weathering index") of a coal sample, several candidate methods were tested with all eight coals from the Argonne Premium Coal Sample Program after air oxidation under relatively mild, controlled environmental conditions. Twenty-five gram aliquots of all eight PCSP coals were exposed to a 10-ml/min dry airflow at 100ºC in all-glass reactors for eight days. Weight changes and O2, CO2, and H2O exchange rates were recorded. Among the various characterization methods tested were FSI, slurry pH, Zeta potential and thermogravimetry. Pyrolysis mass spectrometry and Fourier transform IR spectroscopy were used to monitor structural changes. Results obtained to data show that FSI is a good indicator of oxidation state for low-to-medium caking coals of bituminous rank whereas slurry pH appeared to be less useful for most coals. Although Zeta potential and thermogravimetry tests are still underway, it is becoming quite clear that a reliable, generally useful "weathering index" may have to be based on a fairly comprehensive battery of tests rather than on a single technique.

The Role of Aliphatic and Aromatic Coal Structures and Macerals in Low-Temperature Oxidation Processes

Yun, Y.; Jakab, E.; McClennen, W.H.; Hill, G.R. and Meuzelaar, H.L.C.
ACS Preprints, 32, (1), 1987, Denver, CO. Funded by US Department of Energy.

Low temperature (<100ºC) coal oxidation processes are known to have a pronounced effect on important coal properties such as coking and caking behavior, heat of combustion, floatability, slurry pH, tar yield and extractability. However, the mechanisms and kinetics of the chemical reactions underlying such weathering processes in coal are far from well understood. In this article new Py-MS data on low temperature oxidation effects in several US coals of different rank and origin will be discussed with special emphasis on the role of different coal macerals.

Hydrotreatment Effects on Wilsonville Coal Liquids; Computer-Assisted Evaluation of Multisource Analytical Data

Taghizadeh, K.; Davis, B.H. and Meuzelaar, H.L.C.
ACS Preprint, 32, 4, 1987, New Orleans. Funded by Commonwealth of Kentucky, Kentucky, Energy Cabinet, US Department of Energy and Consortium For Fossil Fuel Liquefaction Science.

Due to the high complexity of coal-derived liquids no single analytical method provides adequate compositional information. In this study, low voltage MS data on Wilsonville coal liquid samples from a single 67-day run in the ITSL mode using Illinois #6 coal were combined with available H and C-13 NMR data, as well as conventional characterization data, by means of computerized multivariate analysis techniques, viz. canonical correlation analysis. The low voltage MS data revealed a high degree of correlation with the NMR data as well as the conventional data. As expected, the hydrotreatment step is characterized by an increase in the relative abundance of hydroaromatic compounds accompanied by a decreased abundance of condensed aromatic hydrocarbons, as well as a strong reduction in heteroatomic compounds. Moreover, the combined effect of catalyst aging and reactor temperature is a decrease in the relative abundance of lower molecular weight-compounds and more reactive chemical structures (e.g., alkyltetralins). Furthermore, during the later stages of the run nitrogen- and sulfur-containing moieties appear to be less efficiently removed in the hydrotreatment step.

Novel Mass Spectrometric Techniques for Coal Devolatilization Studies

Meuzelaar, H.L.C.; Roberts, K.A. and Yun, Y.
Western States Combustion Institute Proceedings, 1987. Funded by ACERC (National Science Foundation and Associates and Affiliates).

Among modern spectroscopic techniques applied to the study of coal devolatilization processes Fourier transform infrared spectroscopy (FTIR) has established a prominent position whereas comparatively little use has been made of mass spectrometry (MS), in spite of its widely recognized speed, sensitivity and high information yields.

Computer Enhanced Analytical Spectroscopy

Meuzelaar, H.L.C. and Isenhour, T.L.
Proc. Snowbird Conference, 1987. Funded by Army Research Office.

This book provides a relatively broad overview of recent advances in computerized optimization, data exploration and spectral interpretation methods in mass spectrometry (MS), infrared spectroscopy (NMR) and nuclear magnetic resonance spectroscopy (NMR).

Multivariate Analysis of Time-Resolved Mass Spectral Data

Windig, W.; Chakravarty, T.; Richards, J.M. and Meuzelaar, H.L.C.
Analytical Chemical Acta, 9, 205-2l8, 1986. 13 pgs. Funded by Army Research Office and Hercules.

Multivariate analysis of time-resolved pyrolysis/mass spectrometric data is described. The approach is based on the variance diagram (VARDIA), a recently developed technique that quantifies the clustering of variables in two-dimensional factor analysis (sub)spaces in a rotational scanning procedure. A maximum in the VARDIA plot indicates a correlated behavior of the mass variables, indicating a common origin. This common origin is generally caused by a change in the concentration of a chemical component. With this information the "factor spectrum" and the scores of the component can be retrieved. For time-resolved serial data, consideration of the clustering behavior of the variables as a function of time is more appropriate than a rotational scanning procedure. Adaptation of the VARDIA for serial data, such as time-resolved data, is described. This approach has the advantage that all the factors can be used. It will be shown that the resolution of the obtained curve can be higher than the total ion current curve as a function of time. Examples will be given for time-resolved data of coal, rubber and wood samples.

Differential Coal Liquefaction, An Economically Viable Way of Producing Liquid, Solid, and Gaseous Fuels

Hill, G.R. and Meuzelaar, H.L.C.
Proc. New Fuels Forms Workshop, 1986. Funded by US Department of Energy, Electric Power Research Institute, Utah Power and Light, and State of Utah.

Although liquefaction yields in the 80-100% range have been regularly reported, it is becoming increasingly clear than an economically viable approach to the production of liquid fuels from coals should seek to optimize rather than maximize liquid yields. These considerations have prompted us to pursue new, "differential" liquefaction avenues characterized by disproportionation of the feedstock coal into two or more valuable end products.