NCJ Number
207702
Journal
Journal of Forensic Sciences Volume: 49 Issue: 6 Dated: November 2004 Pages: 1194-1206
Date Published
November 2004
Length
13 pages
Annotation
This study developed an efficient method for extracting and analyzing gunpowder (propellant) residues collected with double-sided adhesive-coated stubs, which are customarily used for collecting gunshot (primer) residues from suspects or their clothing.
Abstract
This report describes the materials used, the analytical equipment, the shooting experiments and sampling of gunpowder residues, and the extraction of gunpowder residues from stubs and their analysis. Both conductive and nonconductive double-sided adhesives were used, and the analysis was conducted by gas chromatography/thermal energy analyzer (GC/TEA) and ion mobility spectrometry (IMS). The optimal procedure for the extraction involved two stages: extraction of the stubs with a mixture of 80 percent v/v aqueous solution of 0.1 percent w/v of sodium azide and 20 percent v/v of ethanol, using sonication at 80 degrees C for 15 minutes; and residues from the obtained extract were further extracted with methylene chloride. The methylene chloride phase was concentrated by evaporation prior to analysis. Extraction efficiencies of 30-90 percent for nitroglycerine and for 2,4-dinitro toluene (2,4-DNT) were found. No significant interferences in the analysis were observed from the adhesives or skin. Interferences were observed in the analysis by the GC/TEA of the samples collected from hair. This method permitted the analysis of gunpowder residues on a double-sided adhesive-coated stub after it was examined for primer residues by scanning electron microscopy/energy dispersive X-ray spectroscopy. The probative value of the evidence may thus be increased by using this method. 10 figures and 17 references