Forensic Chemistry, March 2022
Michelle N. Torres | Florida International University
José R. Almirall | Florida International University
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 μL 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.
- Development of an Extraction Technique for Ignitable Liquid Residues (ILR) in the Field using Capillary Microextraction of Volatiles (CMV) and Person-Portable GC-MS
- Comparison of Portable and Benchtop GC–MS Coupled to Capillary Microextraction of Volatiles for the Extraction and Analysis of Ignitable Liquid Residues
- Modifications to Capillary Microextraction in Volatiles for the Extraction of Ignitable Liquid Residues
Funding for this article was provided by the Forensic Technology Center of Excellence and the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice.
The opinions, findings, and conclusions or recommendations expressed in this article are those of the author(s) and do not necessarily reflect those of the U.S. Department of Justice.