Feasibility of Gunshot Residue Detection Via Its Organic Constituents. Part I: Analysis of Smokeless Powders by Combined Gas Chromatography-Chemical Ionization Mass Spectrometry

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Abstract
A quick, convenient, and reliable test for detecting gunshot residue is needed to cope with the increasing number of crimes involving handguns. Chemical color tests for nitrates [1] and for antimony, barium, and lead [2] have been used, but these methods lack the required sensitivity and specificity for forensic purposes. Two instrumental techniques, neutron activation analysis and atomic absorption, have found some acceptance by crime laboratories. Neutron activation analysis has been used to detect antimony and barium in hand samples [3], but it suffers from the drawbacks that samples must be sent out for analysis and that it is insensitive to lead. Atomic absorption has been used to detect lead by flame atomization [4], and antimony and barium have been detected with a flameless atomizer [5]. This approach has extended the availability of gunshot residue analysis. However, the costs still limit the number of laboratories with the required equipment. Perhaps a more serious limitation of any technique that is based on the bulk amounts of antimony, barium, or lead on a person's hands is the possibility of environmental or occupational sources of these elements on the hands. This limitation requires setting a threshold often higher than the amount deposited by firing. Furthermore, the amount of residue on the hand declines very rapidly with time.