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Comprehensive Modernization of Firearm Discharge Residue Analysis; Advanced Analytical Techniques, Complexing Agents, and Tandem Mass Spectrometry

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Findings and methodology are presented for research that examined the following three analytical techniques for the detection of firearm discharge residue (FDR) evidence in an effort to modernize its analysis and thus increase its evidentiary value: 1) ion mobility spectrometry (IMS); 2) thermal desorption gas chromatography mass spectrometry (TD-GC/MS); and 3) electrospray ionization tandem mass spectrometry (ESI-MS).
The research found that IMS and TD-GC/MS were “adequate” as screening methods for organic gunshot residue (OGSR). An IMS method for OGSR was validated and then used in a population study to determine shooter from non-shooters by analyzing samples taken from a subject’s hands. Peaks corresponding to three OGSR compounds were detected in about 70 percent of shooter samples. Matrix issues associated with the swab material and subjects’ hands complicated spectra. Results show a need for a pattern-based analysis rather than relying on peak identification for characterizing shooters compared with non-shooter hand swabs. Although additional work is required, ESI-MS showed promise for detecting complexed gunshot residue (GSR) metals. The advantage of coupling ESI-MS and complexation is that it allows for the dual detection of OGSR and GSR. Although modernizing the analysis of FDR is the key to increasing its evidentiary value, apparently coupling the detection of OGSR and GSR is the future of FDR analysis. 29 figures and 18 tables
Date Created: November 13, 2017