Evaluating GC-MS and LC-MS Efficacy for Characterization of a Developed Organic Gunshot Residue Standard

Declan Revenew,* Courtney Vander Pyl, William Feeney, and Tatiana Trejos
Department of Forensic and Investigative Sciences West Virginia University, Morgantown WV 26506

Presentation No.: 111

Assigned Category (Presentation Format): Physical Sciences (Poster Presentations)

Student’s Major: Forensic Chemistry

Organic gunshot residues (OGSR) originate from the ammunition propellant during the discharge of a firearm and are released as vaporous mixtures of explosives, plasticizers, and stabilizers. OGSR transfer and persistence influence the interpretation of this type of evidence; therefore, investigating post-deposition trends can strengthen the understanding of these traces while improving collection methods. Historically, studies have been conducted by sampling individuals after discharging a firearm, limiting precision by the random, unknown quantity of OGSR deposited during a firing event. This project aims to study OGSR persistence on surfaces in a systematic approach using characterized standards as ground truth. The validation and comparison of two analytical techniques (GC-MS, LC-MS) is presented for eight common compounds (nitroglycerin, 2,4-dinitrotoluene, diphenylamine, methyl centralite, ethyl centralite, akardite II, 2-nitrodiphenylamine, and 4-nitrodiphenylamine). Results showed that LC-MS had superior LODs and LOQs, but some analytes were only detected by GC-MS. Furthermore, analysis of variance (ANOVA) shows the stability of the standard over a week (3-time intervals) was not affected by solvent type (ethanol or acetone) during preliminary studies by GC-MS.

Funding: National Institute of Justice; Award No. 2018-DU-BX 0186 and RS-Cx-0009

Program/mechanism supporting research/creative efforts: Other