Continuous vapor sampling of volatile organic compounds associated with explosives using capillary microextraction of volatiles (CMV) coupled to a portable GC-MS

• NCJ Number: 307532
• Journal: Forensic Chemistry Volume: 26 Dated: 2021
• Author(s): Jacqueline L. Rodriguez; José R. Almirall
• Date Published: 2021
• Grant Number(s): DJO-NIJ-21-RO-0002
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical)
• Award: NIJ Co-funding for the NSF Center for Advanced Research in Forensic Science (CARFS)

Annotation

This study examined the coupling of the dynamic sampling and preconcentration device, capillary microextraction of volatiles (CMV), to a portable GC–MS for the rapid field detection of volatile organic compounds (VOCs) associated with explosives and found that the new continuous delivery system achieved significantly higher recoveries (3.0–89%) for all the analytes while requiring less sampling time (∼5 min) and sampling volumes than the other sampling techniques.

Abstract

In this study, the dynamic sampling and preconcentration device, capillary microextraction of volatiles (CMV), is coupled to a portable GC–MS for the rapid field detection of volatile organic compounds (VOCs) associated with explosives. A novel, continuous vapor delivery and sampling system was used, for the first time, to facilitate the delivery of sub-nanogram quantities of explosive analytes.  The new continuous delivery system achieved significantly higher recoveries (3.0–89%) for all the analytes while requiring less sampling time (∼5 min) and sampling volumes than the other sampling techniques. The rapid sampling and preconcentration of sub-ng levels of VOCs in field scenarios was coupled to a ∼10-minute portable GC–MS method that compares favorably to the analytical figures of merit achieved by laboratory benchtop instruments and approximates the detection limits reported for canines. The results of the portable GC–MS were compared to a benchtop GC–MS throughout this study. Sub-nanogram (ng) instrumental detection limits were achieved for each of the following analytes of interest (3-NT, 2,4-DNT, DPA, EC, DBP and 2-NDPA). Three different dynamic sampling methods were used with the CMV to sample and preconcentrate the volatiles prior to analysis. The headspace of a closed system was sampled over 10 min resulting in recoveries between 0.3 and 12%. Simulated open-air vapor sampling using a previously described vapor source resulted in an improvement of analyte recovery (ranging from 1.6 to 25%), for the same 10-minute sampling. (Published Abstract Provided)