| The research presented herein describes the development and optimization of scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) and inductively-coupled plasma mass spectrometry (ICPMS) for the analysis of gunshot residue (GSR) on decomposing tissue. Two euthanized pigs were obtained from the MSU Swine Facility. One pig was shot 10 times with a Glock 9mm pistol and the other served as the source of the control tissue samples. Each day, a gunshot wound and a control tissue sample was excised from each pig over a 7-day sampling period. Three methods of sample preparation were attempted prior to SEM/EDS analysis; air-drying, freeze-drying, and tape-lifting. GSR consisting of Sb, Ba, and Pb was found by SEM and analyzed by EDS on the tape-lifts from days 1 and 2. ICPMS was used to analyze gunshot wounds and control tissue for 121Sb, 138Ba, and 208Pb after preparing the samples by microwave digestion. GSR was determined in the gunshot wounds throughout the course of the 7-day sampling period in concentrations ranging from 9.19mug of 121Sb per gram of tissue (mug/g) to 0.15 mu/g, 138Ba was determined in the range of 30.67 -- 0.06 mug/g, and 208Pb was determined in he range of 26.71 -- 0.10 mug/g. ICPMS had a linear response between 0 -- 1000 ppb for 121Sb, 138Ba, 208Pb and the limits of detection were 0.002, 0.033, and 0.009 ppb, respectively. |
