Time-of-Flight Mass Spectrometry for Multidimensional Gas Chromatography and Related Fast-GC Techniques

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PROJECT SUMMARY This award provides funds to acquire a time-of-fight mass spectrometer (TOF-MS) to augment existing research systems for the analysis of complex organic mixtures. Such a mass spectrometer permits continuation of research involving development of multidimensional gas chromatography (MDGC) and thermal-gradient programmed gas chromatography (TGPGC). This equipment enhances the ability to develop faster GC-MS investigations of combustion residues and effluents, as well as other types of environmental samples. Because TOF-MS is inherently faster than conventional quadrupole or ion-trap MS systems, it is possible to exploit fast GC technologies (such as TGPGC) and integrate them into developing MDGC work. This greatly increases the information that can be gathered for ongoing efforts relating to combustion effluents, organic residues, and endocrine-disrupting chemicals (EDCs). High-speed gas chromatography is itself a growing and popular research area. Conventional open tubular columns (OTCs) that have small internal column diameters are available for high-speed GC separations. Since many microbore OTC techniques have significant shortcomings in sample solute capacity and detection limits, we continue to develop alternative techniques (such as TGPGC) to conduct high-speed GC that do not require microcolumns and ultra-sensitive detectors. Fast GC systems that possess high-solute capacity have the potential to perform analytical and process control in combustion systems, monitor emissions, and perform routine or established tests more quickly and efficiently. The most difficult aspect of faster GC analyses, however, is that faster-response detectors are absolutely required. Arguably, the most useful and powerful detector for gas chromatography is the mass spectrometer, due to its sensitivity, specificity, and identification ability. However, because it is a scanning instrument, the time required to collect mass spectral tracings is significant in relation to the speed at which a solute zone will elute from the chromatographic column. Therefore, what is needed in order to pursue the development of these analytical instruments is a mass spectrometer that is several orders of magnitude faster in scanning speed, and yet similar in sensitivity to much slower quadrupole and ion-trap MS instruments. Time-of-flight mass spectrometry (TOF-MS) can provide this type of analytical speed without sacrificing sensitivity or qualitative capability. Broader impactStudies are underway to develop and use multidimensional gas chromatography-mass spectrometry (MDGC-MS) to investigate combustion emissions and residues. By identifying as many components as possible from emissions and residues, risk assessments can be more accurately performed and interpreted. Typically, a two-column GC system is used in which a primary column is operated to maximize the resolution of coeluting components, while a secondary sequential column is operated such that remaining analytes are separated very quickly using a stationary phase dissimilar to the primary column. Fast GC within the secondary channel is the critical aspect of this analysis.