Detection of Gunshot Residues from Leaded and Non-leaded Ammunition by Electrochemical Sensors and LIBS

Tuesday, March 09, 2021: 10:45 AM - 11:05 AM

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Description

This study developed a reliable screening of inorganic and organic gunshot residues using laser‐induced breakdown spectroscopy (LIBS) and electrochemical screen-printed carbon electrodes. The methods are capable of detecting GSR in just a few minutes with high specificity and sensitivity. The proposed approach provides a novel alternative to identifying gunshot residues from various substrates (hands, fabrics, glass, wood) and modern ammunition, including leaded and non-leaded. A benefit afforded by this approach is the use of the universal hand's collection method currently used by practitioners and minimal damage to the sample, allowing for further confirmation by SEM-EDS when needed. Neural network algorithms were used to classify samples derived from shooters' hands (leaded, non-leaded, and mixture residues) and non-shooters (background population). Accuracy ranging from 95 to 98% was observed for 2400 samples collected from the hands of 300 non-shooters and 400 shooters. Cross-validation by SEM-EDS and LC/MS/MS was performed for a subset, after LIBS and EC screening. Moreover, LIBS's application to bullet hole identification and shooting distance determination was evaluated on a dataset of 180 fabrics, drywall, and wooden samples. Statistical methods, like principal component analysis and multivariate discriminant analysis, were performed to estimate shooting distances and identify the presence of GSR residues. Significantly superior classification rates were observed for LIBS as compared to traditional color tests. The use of these rapid screening tools, in conjunction with statistical methods, offers objective decisions and more efficient case management in firearm‐related investigations.

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Additional Info

Keywords: Please select up to 4 keywords ONLY:
Laser,Neural Network,Voltammetry,Spectroscopy,Statistics