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New Method for Collection and Identification of Gunshot Residues From the Hands of Shooters

NCJ Number
Journal of Forensic Sciences Volume: 48 Issue: 6 Dated: November 2003 Pages: 1269-1274
Edson L. T. Reis B.S.; Jorge E. Souza Sarkis Ph.D.; Osvalda N. Neto Ph.D.; Claudio Rodrigues Ph.D.; Mauricio H. Kakazu M.S.; Sonia Viebig B.S.
Date Published
November 2003
6 pages
This article discusses a new collection method for gunshot residues (GSR).
In criminal investigations, analyses of GSR are usually required to determine whether or not a suspect discharged a firearm, to confirm a bullet entrance hole, or to estimate a firing distance. Different methods have been used successfully in forensic laboratories for GSR analysis, including neutron activation analysis (NAA). The collection method discussed involves moistened swabs with ethylenediaminetetraacetic acid (EDTA), a powerful and well-known complexing agent. Detection was via a sector-field inductively coupled plasma mass spectrometry (HRICP-MS). The proposed collection and analytical method allowed detection of antimony (Sb), barium (Ba), and lead (Pb) after .38 shot tests, at detection limits in four different areas of the hands of volunteers. A discussion is presented concerning hand areas near the thumb and forefinger as being more suitable for GSR collection. Comparison was made using 2 percent diluted EDTA, 2 percent nitric acid solution, and simple deionized water as collecting solutions. Considering its chemical properties, low cost, and high degree of safety (compared with nitric acid) and that it does not irritate the skin, 2 percent EDTA solution was used for GSR sampling, prior to the determination of Sb, Ba, and Pb. The results show a clear advantage of EDTA for GSR collection, allowing a good recovery of analytes, not only before but also after test shots. Diluted nitric acid performed better than deionized water. Analyte measurements on extracts from some volunteers before any test shots revealed the strong influences of occupational activities and environment, but were not influenced directly by natural components present on the skin instead, since previous studies identified only potassium, sodium, magnesium, phosphorus, calcium, and silicon as the main elements present. 2 figures, 3 tables, 29 references