title: The development and comparison of collection techniques for inorganic and organic gunshot residues.
abstract: The detection and interpretation of gunshot residues (GSR) plays an important role in the investigation of firearm-related events. Commonly, the analysis focuses on inorganic particles incorporating elements derived from the primer. However, recent changes in ammunition formulations and possibility that particles from non-firearm sources can be indistinguishable from certain primer particles challenge the standard operational protocol and call for adjustments, namely the combination of inorganic and organic GSR analysis. Two protocols for the combined collection and subsequent analysis of inorganic and organic GSR were developed and optimised for 15 compounds potentially present in organic GSR (OGSR). These protocols were conceptualised to enable OGSR analysis by ultrahigh-performance liquid chromatography (UHPLC) coupled with UV detection and triple quadrupole tandem mass spectrometry (confirmation) and IGSR analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). Using liquid extraction, the extraction recoveries from spiked swabs and stubs were ~80 % (50-98 % for swabs, 64-98 % for stubs). When the mixed OGSR standard was applied to the hands and recovered in the way that is usual for IGSR collection, GSR stubs performed significantly better than swabs (~30 %) for the collection of OGSR. The optimised protocols were tested and compared for combined OGSR and inorganic GSR analysis using samples taken at a shooting range. The most suitable protocol for combined collection and analysis of IGSR and OGSR involved collection using GSR stubs followed by SEM-EDX analysis and liquid extraction using acetone followed by analysis with UHPLC.
authors.affiliation: Centre for Forensic Science, University of Technology, P.O. Box 123, Broadway, Sydney, New South Wales, 2007, Australia.
authors.forename: Regina Verena
authors.initials: RV
authors.lastname: Taudte
authors.affiliation: Centre for Forensic Science, University of Technology, P.O. Box 123, Broadway, Sydney, New South Wales, 2007, Australia.
authors.forename: Claude
authors.initials: C
authors.lastname: Roux
authors.affiliation: Centre for Forensic Science, University of Technology, P.O. Box 123, Broadway, Sydney, New South Wales, 2007, Australia.
authors.forename: Lucas
authors.initials: L
authors.lastname: Blanes
authors.affiliation: Forensic Ballistics Investigation Services Group, NSW Police Force, 151-241 Goulburn Street, Surry Hills, Sydney, New South Wales, 2010, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Horder
authors.affiliation: School of Chemical and Physical Sciences, Flinders University, Bedford Park, Adelaide, South Australia, 5001, Australia.
authors.forename: K Paul
authors.initials: KP
authors.lastname: Kirkbride
authors.affiliation: Centre for Forensic Science, University of Technology, P.O. Box 123, Broadway, Sydney, New South Wales, 2007, Australia. alison.beavis@uts.edu.au.
authors.forename: Alison
authors.initials: A
authors.lastname: Beavis
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005389:Firearms; D007287:Inorganic Chemicals / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D009930:Organic Chemicals / Q000032:analysis*; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007287:Inorganic Chemicals; D009930:Organic Chemicals
keywords: Alcohol wipes; GSR stubs; Gunshot residues; Inorganic; Liquid extraction; Organic