Forensic analysis of smokeless powders has historically focused on the analysis of unburned powder or gunshot residue. The analysis of fired cartridge residues and subsequent statistical association to the corresponding unburned powder has only recently been investigated. Previous work in our laboratory employed liquid chromatography-time of flight-mass spectrometry (LC-TOFMS) and chemometric procedures to investigate association of fired cartridge residues to the corresponding unburned powders.2 While successful association was achieved for some powders, LC-TOFMS is not readily available in forensic laboratories. A widely available alternative is gas chromatography-mass spectrometry (GC-MS). The work presented here demonstrates the use of GC MS for the analysis of unburned powder and fired cartridge residues, followed principal components analysis (PCA) and hierarchical cluster analysis (HCA) to investigate association and differentiation of fired cartridge residues to the corresponding unburned powder. Both PCA and HCA resulted in distinct groupings of the unburned powders, based largely on the abundance of ethyl centralite and dibutyl phthalate. Despite variability and decreased abundances observed in all fired cartridge residues, successful association of the fired cartridges to the corresponding unburned powder was possible but was limited by the original composition of the unburned powder. Overall, this work demonstrates that GC-MS and chemometric procedures are effective tools for the association of fired cartridge residues and unburned powders.
Read
