Dworzanski, JP
1996
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.
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
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
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.
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.
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.
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.
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
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.
Optimization of Transfer Line Gas Chromatography for Direct Atmospheric Vapor Sampling Ion Mobility Spectrometry Application
Arnold, N.S.; Kim, M.-G.; McClennen, W.H. and Dworzanski, J.P.
Workshop on Ion Mobility Spectrometry, Mescalaro, AZ, June 1992. Funded by US Army/Chemical Research Development and Engineering Center.
An automated vapor sampling (AVS) device has proved powerful for atmospheric (and other) vapor sampling applications when coupled with the "preseparation" available via rapid transfer line gas chromatography (TLGC) prior to detection by a "smart" detector. Initial applications of AVS TLGC utilized mass spectrometric (MS) detection along with rapid repetitive sampling to monitor on-line test reactors and industrial processes. Subsequent work extended this technique to AVS TLGC/FTIR for the monitoring of evolution products from a thermogravimetric analyzer. Most recently this technique has been extended to ion mobility spectrometry (IMS).
Because the AVS device samples directly from the ambient environment at the inlet into the GC column without any intervening mechanical parts (e.g. syringes, pumps, etc.), the GC column itself must function as a pressure restrictor between the sampled environment and a detector operated at reduced pressure. This technique found its first application in AVS TLGC/MS where the merits of vacuum outlet GC and the requirement of capillary flow restriction are obvious. Yet, the extension to detectors that are ordinarily operated at atmospheric pressure (i.e., IMS and FTIR) by pulling up to ½ atmosphere of vacuum on the detector cell has also proved successful.
These successes have motivated a search for "optimal" performance based upon the selection of appropriate column parameters for both separation and flow restriction criteria. Specifically, this paper evaluated the performance for AVS TLGC/IMS separations from the perspective of resolution, speed of separation and sensitivity.
1991
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.
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.
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.
Dworzanski, JP
1996
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.
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
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
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.
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.
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.
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.
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
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.
Optimization of Transfer Line Gas Chromatography for Direct Atmospheric Vapor Sampling Ion Mobility Spectrometry Application
Arnold, N.S.; Kim, M.-G.; McClennen, W.H. and Dworzanski, J.P.
Workshop on Ion Mobility Spectrometry, Mescalaro, AZ, June 1992. Funded by US Army/Chemical Research Development and Engineering Center.
An automated vapor sampling (AVS) device has proved powerful for atmospheric (and other) vapor sampling applications when coupled with the "preseparation" available via rapid transfer line gas chromatography (TLGC) prior to detection by a "smart" detector. Initial applications of AVS TLGC utilized mass spectrometric (MS) detection along with rapid repetitive sampling to monitor on-line test reactors and industrial processes. Subsequent work extended this technique to AVS TLGC/FTIR for the monitoring of evolution products from a thermogravimetric analyzer. Most recently this technique has been extended to ion mobility spectrometry (IMS).
Because the AVS device samples directly from the ambient environment at the inlet into the GC column without any intervening mechanical parts (e.g. syringes, pumps, etc.), the GC column itself must function as a pressure restrictor between the sampled environment and a detector operated at reduced pressure. This technique found its first application in AVS TLGC/MS where the merits of vacuum outlet GC and the requirement of capillary flow restriction are obvious. Yet, the extension to detectors that are ordinarily operated at atmospheric pressure (i.e., IMS and FTIR) by pulling up to ½ atmosphere of vacuum on the detector cell has also proved successful.
These successes have motivated a search for "optimal" performance based upon the selection of appropriate column parameters for both separation and flow restriction criteria. Specifically, this paper evaluated the performance for AVS TLGC/IMS separations from the perspective of resolution, speed of separation and sensitivity.
1991
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.
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.
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.