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A new quantitative method for gunshot residue analysis by ion beam analysis.
Matthew E Christopher1, John-William Warmenhoeven, Francesco S Romolo
1Surrey Ion Beam Centre, University of Surrey, GU2 7XH, UK.
The Analyst
|June 19, 2013
Summary
A new proton microbeam method offers faster, quantitative analysis of gunshot residue (GSR) particles. This technique accurately groups ammunition types with over 99% confidence, improving forensic evidence discrimination.
Area of Science:
- Forensic Science
- Materials Science
- Analytical Chemistry
Background:
- Scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) is a standard but limited technique for gunshot residue (GSR) analysis.
- Existing methods face challenges with trace element sensitivity and quantitative results from small particles.
Purpose of the Study:
- To present a novel, faster, and non-destructive method for quantitative elemental analysis of single GSR particles.
- To assess the precision of the new method and its ability to discriminate ammunition types.
Main Methods:
- Utilized a scanning proton microbeam with Particle Induced X-ray Emission (μ-PIXE) and Elastic Backscattering Spectrometry (EBS).
- Analyzed GSR particles for elemental composition, focusing on lead (Pb), barium (Ba), and antimony (Sb).
- Applied multivariate analysis to determine ammunition grouping behavior.
Main Results:
- The μ-PIXE and EBS method provides non-destructive, quantitative elemental analysis of single GSR particles.
- The method demonstrated high precision in elemental composition assessment.
- Multivariate analysis successfully grouped different ammunition makes with >99% confidence.
Conclusions:
- The presented μ-PIXE and EBS protocol offers a significant advancement over traditional SEM-EDS for GSR analysis.
- This new technique enhances the discrimination power for forensic evidence by accurately grouping ammunition types.
- The method's speed and quantitative accuracy make it a valuable tool in forensic investigations.
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