Validation of gunshot residue analyses method by lnductively Coupled Plasma Mass Spectrometry on hand swabs at the National lnstitute of Legal Medicine and Forensic Sciences, Bogotá's Regional Branch Office
DOI:
https://doi.org/10.60007/antistio.4545Keywords:
gunshot residues, antimony, barium, lead, inductively coupled plasma-mass spectrometry (ICP-MS)Abstract
A validation method was developed for the determination of antimony, barium and lead as the interest analytes in the analysis of gunshot residues collected from hands by the nitric acid technique. The analytical technique used was inductively coupled plasma mass spectrometry (ICP-MS). The analytical parameters evaluated were: specificity or selectivity, linearity, precision, detection limit, sensitivity, accuracy.
The method is lineal in the range of the studied concentrations (5 ug/l- 500 ug/l) for antimony (121Sb), barium (138Ba) and lead (208Pb). The detection limits for the analites are 0.174, 0.807, 0.153 ug/l, respectively. The method also complies with the precision criteria (CV% < 5%) and allows the determination of the analite levels without interference due to signals arising from the cotton in the swabs and from blood, which are common contaminants in forensic casework. For the studied analites sensitivities greater than 1 were obtained. Using the "Paired T" test it was possible to determine that the validated method is able to differentiate between shot and non shot, allowing to answer in a positive way the question asked at the beginning of chis investigation: is it possible to determine the presence of antimony, barium and lead in samples collected from the hands by the nitric acid technique, as evidence in judicial investigations involving fireguns, by ICP-MS?
Due to all chis, the methodology complies with the parameters taken into account during chis validation study; therefore, the results obtained during the evaluation of samples for analysis of gunshot residues collected from hands are reliable.
Author Biography
María Constanza Moya Jiménez, Instituto Nacional de Medicina Legal y Ciencias Forenses. Bogotá, Colombia
Química. Laboratorio de Evidencia Traza. Instituto Nacional de Medicina Legal y Ciencias Forenses. Bogotá, Colombia.
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