Field evaluation of a prototype man-portable GC/MS

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. The vacuum system and power supplies were replaced to facilitate operation on 24 Vdc 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 o-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/MS formore » identification and quantitation of unknown vapors.« less