Scanning electron microscopy combined with energy dispersive X-ray analysis (SEM/EDX) was used to identify the gunshot residue (GSR) particles discharged by lead-free Sintox ammunition. Sintox GSR particles are characterized by spheroidal particles mainly consisting of titanium (Ti) and zinc (Zn). The results obtained in this study are in agreement with the hypothesis that GSR particles are formed by rapid condensation and solidification of vaporized and molten primer and bullet materials as a result of sudden temperature quench. The surface morphology of Ti-Zn particles is an essential criterion for their identification as gunshot residue particles and for discrimination against Ti-Zn environmental particles.

Within the framework of the ENFSI Expert Working Group “Firearms,” a proficiency test on the detection and identification of GSR by SEM/EDX was organized and performed. The test material was designed by the Bundeskriminalamt and manufactured to order by an external company for SEM accessories. The participating laboratories were requested to determine the total number of PbSbBa-containing particles on the test samples following their own laboratory specific methods of automated GSR particle search and detection by SEM/EDX. Two similar samples with synthetic GSR particles were dispatched to all participants in order to gain additional information on systematic errors within the obtained results (split-level study), whereas one sample was supplied only with PbSbBa particles, and the second one was additionally contaminated with some environmental particles. This report summarizes the results of the study as well as a statistical evaluation and comparison with previous studies.

Within the framework of the ENFSI Expert Working Group “Firearms,” every second year, a proficiency test on the detection and identification of GSR by SEM/EDX is carried out. This proficiency test is a development and extension of the previous proficiency test GSR2001. The test material was again designed by the organization panel and manufactured by an external company for SEM accessories. This time the participating laboratories were requested to determine the total number of PbSbBa containing particles on a test sample following their own laboratory specific methods of automated GSR particle search and detection by SEM/EDX. One synthetic particle sample (SPS) with artificial GSR particles was dispatched to all participants. This paper summarizes the results of the study and assesses the overall performance of the participating laboratories. Furthermore an extended statistical evaluation and a comparison with previous studies was carried out.

Within the framework of the ENFSI Expert Working Group "Firearms" a proficiency test on the detection and identification of GSR by energy-dispersive scanning electron microanalysis (SEM/EDX) is carried out in a 2 years term. The latest test was performed in 2005/2006 and was denoted as GSR2005. Seventy-five laboratories from 28 countries participated in this proficiency test and submitted in total 83 independent data-sets. The participating laboratories were requested to determine the total number of PbSbBa containing particles on a synthetic test sample following their own laboratory specific methods of automated GSR particle search and detection by SEM/EDX. Furthermore size and position of the detected particles had to be reported by the laboratories and were evaluated statistically. The results were compiled by means of z-scores according to the IUPAC and EURACHEM guidelines-assessing individual laboratory achievements (inter-laboratory) as well as intra-laboratory performance-and were compared to the results of the previous proficiency test run GSR2003 (1). The comparison shows that there is a noticeable improvement in the method's detection capability.

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