Identification and highly selective differentiation of organic gunshot residues utilizing their elemental and molecular signatures

Shelby R Khandasammy; Lenka Halámková; Matthieu Baudelet; Igor K Lednev

doi:10.1016/j.saa.2023.122316

Identification and highly selective differentiation of organic gunshot residues utilizing their elemental and molecular signatures

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Apr 15:291:122316. doi: 10.1016/j.saa.2023.122316. Epub 2023 Jan 3.

Authors

Shelby R Khandasammy¹, Lenka Halámková², Matthieu Baudelet³, Igor K Lednev⁴

Affiliations

¹ Department of Chemistry, University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, United States.
² Department of Environmental Toxicology, Texas Tech University, 2500 Broadway, Lubbock, TX 79409, United States.
³ Department of Chemistry, University of Central Florida, 4111 Libra Drive, Physical Sciences Bld. Rm. 255, Orlando, FL 32816, United States; National Center for Forensic Science, University of Central Florida, 12354 Research Parkway #225, Orlando, FL 32826, United States; CREOL - The College of Optics and Photonics, University of Central Florida, 4304 Scorpius Street, Orlando, FL 32816, United States.
⁴ Department of Chemistry, University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, United States. Electronic address: ilednev@albany.edu.

PMID: 36634494
DOI: 10.1016/j.saa.2023.122316

Abstract

Firearm related evidence is of great significance to forensic science. In recent years, many researchers have focused on exploring the probative value of organic gunshot residue (OGSR) evidence, which is often bolstered by many factors including recoverability. In addition, OGSR analysis has shown the potential to achieve differentiation between OGSRs generated from various ammunition brands and/or calibers. Raman spectroscopy is a vibrational spectroscopic technique which has been used in the past for gunshot residue analysis-including OGSR specifically. Raman spectroscopy is a nondestructive, highly-selective, simple, and rapid technique which provides molecular information about samples. LIBS or Laser-Induced Breakdown Spectroscopy is a simple, robust, and rapid analytical method which requires minimal to no sample preparation and a small amount of sample for analysis. LIBS provides information on the elemental compositions of samples. In this study, Raman spectroscopy and LIBS were used together in sequence in an attempt to achieve the specific identification and characterization of OGSR particles from ammunition types which were closely related. The main goal was to determine if this method had the potential to differentiate between various ammunition types of the same caliber and produced by the same manufacturer, and generated under identical firing conditions. High-resolution optical microscopy documented the OGSR particles' morphologies and Raman spectroscopy was used to identify particles as OGSRs. Finally, LIBS analysis of the OGSR particles was carried out. Advanced chemometric techniques were shown to allow for very successful differentiation between the OGSR samples analyzed.

Keywords: Chemometrics; Forensics; LIBS; Organic gunshot residue; Raman spectroscopy.