Methods of extraction of gunshot residue (GSR) swabs for determination of antimony (Sb), barium (Ba), and lead (Pb) by flameless atomic absorption spectrophotometry (AAS) have been studied. Optimum extraction parameters were determined using recovery studies of Sb, Ba, and Pb added to swabs at amounts representative of actual GSR and handblank levels. Two difficulties with most extraction-AAS procedures are incomplete extraction of Sb and incorrect Ba results arising from improper matching of sample and standard matrices before AAS determinations. Utilization of standards made by spiking analyte elements on swabs and extraction along with samples by an efficient procedure minimizes errors in Sb, Ba, and Pb determination.
Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was compared with atomic absorption spectrophotometry (AAS) for barium determination in gunshot residue (GSR) collection swabs. Lack of interferences by common swab extract constituents, a wide linear dynamic range, and good precision and accuracy of ICP-AES make it superior to AAS for barium determination in GSR swab extracts.
Two modifications to a previously reported extraction procedure for determination of antimony, barium, and lead in gunshot primer residue swab extract solutions have been studied. Removal of cotton tips from swabs by cutting their shafts results in extraction efficiencies for all elements that compare favorably with those obtained by complete removal of the cotton from the swab shaft. Swab-mounted standards can be made and stored in a dry condition for periods of at least four months before use without adverse effects on analytical results. Long-term relative precision estimates for the combined extraction and analysis are approximately 5% for all three elements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.