Evaluation of capillary microextraction of volatiles (CMV) coupled to a person-portable gas chromatograph mass spectrometer (GC-MS) for the analysis of gasoline residues

A novel dynamic headspace extraction device, the capillary microextraction of volatiles (CMV) was coupled to a person-portable GC-MS for the analysis of ignitable liquid residues (ILR) sampled from simulated fire debris. A benchtop GC-MS was used as a benchmark for the performance of the portable GC-MS. The use of a paper cup in conjunction with the CMV for in-field sampling of the VOCs associated with ILRs is presented for the first time. A five-minute sampling/extraction protocol was sufficient to recover six (6) analytes: toluene, ethylbenzene, mxylene, o-xylene, 4-ethyltoluene, and 1,2,4-trimethylbenzene from a 0.01 mu L spike of gasoline, with typical mass recoveries of 4-24 ng. Extractions from water-logged debris resulted in reliable detection of the same six compounds but up to 62% less was retained relative to dry debris. Recoveries for detected analytes ranged between 1 and 5% at several solution spike volumes suggesting proportional retention by the CMV. The CMV also demonstrated greater extraction capabilities than the portable GC-MS air sampling wand. Out of a 20-component mixture, 17 compounds were detected compared to the wand's 13, with the majority of these at higher overall intensities for CMV. An overall 21-minute analytical method was developed using the CMV/Cup protocol capable of detecting several ILR-associated compounds at up to 10x greater sensitivity than traditional extraction techniques such as activated charcoal strips and SPME fibers.

Automated summary

The novel dynamic headspace extraction device, CMV, when coupled with a person-portable GC-MS, demonstrated effectiveness for the analysis of ILRs in field sampling. The use of a paper cup in conjunction with CMV for in-field VOC sampling was introduced for the first time. CMV showed greater extraction capabilities than portable GC-MS and higher sensitivity compared to traditional extraction techniques.