Detection of Odor Signatures of Smokeless Powders Using Solid Phase Microextraction Coupled to an Ion Mobility Spectrometer

• NCJ Number: 240016
• Journal: Forensic Science International Volume: 188 Dated: 2009 Pages: 112-118
• Author(s): Monica Joshi; Yisenny Delgado; Patricia Guerra; Hanh Lai; José R. Almirall
• Date Published: 2009
• Length: 7 pages
• Grant Number(s): 2006-DN-BX-K027
• Publication Type: Research (Applied/Empirical)

Annotation

This article presents the methodology and findings of a study that extracted odor signature compounds characteristic of smokeless powders, which are low explosives commonly used in homemade explosive devices, followed by their detection by ion mobility spectrometers (IMS).

Abstract

Traditionally, canines have been used as biological detectors of explosives. The compounds that the canines alert to are reported as the odor chemicals of the compounds of interest; however, canine trials have reported that the dogs show little or no interest in some of the volatile molecules detected by instrument techniques in the headspace of the target compound. The study reported in this article involved the IMS detection of some of these compounds extracted from the headspace of different smokeless powders for the first time. The expected mass of the compounds extracted and the method detection limits are also reported. The smokeless powder additives reported include diphenylamine (DPA), ethyl centralite, 2-ethyl 1-hexanol, and 2.4-dinitrotoluene. The pre-concentration of these volatile odor chemicals from various commercial smokeless powers onto a solid phase microextraction (SPME) device followed by IMS analysis was demonstrated. Chosen for this study were five samples of smokeless powder representing double-based and single-based powders from three popular commercial brands. Diphenylamine was found to be a common additive among all the powders tested. The mass of the analytes in the headspace available for detection was determined from response curves of the corresponding standards. The response curves were produced by printing precise amounts of standards onto substrates and analyzing them. The absolute detection limits were also determined from these response curves, with the values ranging from 0.12 to 1.2 ng for the standards. Typical extraction times ranged between 5 and 40 min., and the mass of diphenylamine and ethyl centralite extracted at the lowest extraction times was found to be greater than the LOD of the compounds. 5 figures, 4 tables, and 30 references