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Rapid Screening and Confirmation of Organic GSR using Electrospray Mass Spectrometry

NCJ Number
Bruce McCord, Ph.D.; Jennifer Greaux Thomas, B.S.
Date Published
December 2013
125 pages
This project developed a rapid separation and detection method for identifying additives in common smokeless powder - which can be used as the explosive component in pipe bombs and the propellant in modern ammunition - along with their decomposition products, using ultra performance liquid chromatography mass spectrometry.
These additives and their decomposition products are generally described as gunshot residue (GSR). Because each manufacturer changes the composition of the propellant powder so that it performs in a specific manner, it is possible to use variances in composition in order to differentiate between brands and possibly lots of the same powder. Ultra Performance Liquid Chromatography (UPLC) with Tandem Mass Spectrometry (MS/MS) was used to analyze the smokeless powders and organic gunshot residue. UPLC was chosen because it can accommodate higher backpressures and smaller particle column than HPLC. It also enables users to perform a more efficient and rapid separation. MS/MS was used, along with ESCI, in order to detect the wide array of compounds found in smokeless powder. Results of a small-scale study showed that quantifiable differences are present in the additive profile of powders from different brands and lots of smokeless powder; however, a larger population of powders must be characterized in order to determine the probative nature of these differences. In the second phase of the study, gunshot residue samples were collected from the hands of a shooter and analyzed to test the method's applicability in firearm cases. The results found characteristic differences in the UV and MRM profiles based on the type of ammunition fired. These results show the potential of the technique for distinguishing class differences based on ammunition type in addition to the standard determination of GSR on the shooter's hands. Procedures for collection and analysis are described in detail. 47 figures, 25 references, and dissemination information