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Initial Evaluation of Inlet Thermal Desorption GC-MS Analysis for Organic Gunshot Residue Collected From the Hands of Known Shooters

NCJ Number
Forensic Chemistry Volume: 2 Dated: November 2016 Pages: 55-62
Date Published
November 2016
8 pages

This research project evaluated a commercially available thermal separation probe that fits directly into the injection port as a means of sample introduction for gas chromatography/mass spectrometry (GC/MS) operated in a selected ion monitoring mode.


The discharge of a firearm produces a wealth of physical and chemical evidence. Traditional forensic analysis has focused on inorganic particulates formed from the primer, referred to as gunshot residue (GSR). The last few years have seen interest in expanding the list of target compounds to include organic constituents of firearm discharge residue (OGSR). To facilitate adoption by the forensic community, new assays ideally should exploit instrumentation commonly found in forensic laboratories, such as GC/MS. In the current study, a statistical approach utilizing bivariate plots linked retention time to ion ratio data to afford a probabilistic interpretation of the results. A total of 27 authentic shooter swabs were collected after firing 1-5 rounds and were analyzed in halves or triplicates. Ethyl centralite was detected in 81 percent of the samples; diphenylamine in 56 percent and 2-nitrodiphenylamine in 14 percent. Dimethyl and dibutyl phthalates were detected in most of the swabs, but also in many of the hand swab blanks. The use of surrogate standards provided a measure of recovery and reproducibility for retention times and ion ratios. (publisher abstract modified)

Date Published: November 1, 2016