Page 1 of 16 Detection of Organic Components of Gunshot Residue on Carbon SEM Stubs by Raman Spectroscopy

Current methods of gunshot residue (GSR) analysis concentrate on identification of the inorganic components of ammunition primer. Single particles with morphology indicative of formation in a high heat environment and containing the elements lead, barium, and antimony are considered characteristic of GSR. Scanning electron microscopy with energy dispersive xray spectrometry (SEM-EDS) is the widely accepted method to determine both elemental composition and morphology. Although this is a very effective method, the probative value of inorganic GSR analysis is limited. Not only are there limitations on the sample containing three component particles, but current and future formulations of “green” lead-free ammunition will lead to an increasing probability of false negatives. The organic component of the GSR has not been utilized during analysis thus far. Chromatography with mass spectroscopy has been proposed as a way to identify the components of these organic compounds, but at the expense of the sample. There would be no way to identify if inorganic components are present after this examination. With recent advancements in Raman spectroscopy technology, new techniques are able to be developed. This study introduces early research into the ability to detect and characterize organic residues deposited on the standard 12.7 mm SEM stubs, while still allowing for subsequent traditional SEM-EDS analysis.