Comparison of three collection methods for the sodium rhodizonate detection of gunshot residues on hands

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State: Public
Version: Final published version
License: All rights reserved
Serval ID
serval:BIB_7CB0C4602585
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Comparison of three collection methods for the sodium rhodizonate detection of gunshot residues on hands
Journal
Science & Justice
Author(s)
Werner Denis, Gassner Anne-Laure, Marti Jorina, Christen Stephan, Wyss Philipp, Weyermann Céline
ISSN
1355-0306
ISSN-L
1355-0306
Publication state
Published
Issued date
2020
Peer-reviewed
Oui
Volume
60
Number
1
Pages
63-71
Language
english
Abstract
The aim of this study was to compare three gunshot residue (GSR) collection methods used in conjunction with chemographic detection applied by different regional Swiss police services. The specimens were collected from the hands of a shooter with either filter paper (Filter method) or adhesive foil. The adhesive foil was then either applied against photographic paper during visualisation (AF Photo method) or coated with a layer of polyvinyl alcohol (AF PVAL method). The experiments involved two conditions of the examined hands, i.e. dry and humidified. The residues were revealed using the sodium rhodizonate test (SRT). Preliminary tests assessing the possibility of conducting a confirmatory Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (SEM/EDX) analysis after the chemographic test were performed on a number of specimens by cutting positive spots and mounting them on stubs. Obtained results were compared in terms of effectiveness - number of positive spots, time requirements, quality of subsequent SEM-EDX analysis, ease of use and cost.
The Filter method generally yielded a high-quality detection with both dry and humidified hands, as well as a simple, quick and efficient confirmation by SEM/EDX. The AF Photo performed well on dry hands, but not on humidified hands. The AF PVAL method performance was lower compared to the other methods in both examined conditions of the hands. The SEM/EDX analysis showed that the Filter and AF PVAL method provided satisfactory results when a sufficient carbon coating thickness was applied to the cuttings. It was also observed that the thinner the PVAL layer, the better the quality of the spectra and obtained images in SEM/EDX. Furthermore, the surface of the photographic paper did not seem to be conductive, even after the application of a thick layer of carbon.
In conclusion, the Filter method gave the best overall results, but its application required slightly more time and expertise than the two other methods.
Keywords
Firearm discharge residues, Chemographic detection methods, Filter paper, Adhesive foil, Photographic paper (PVAL), Scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDX)
Pubmed
Web of science
Create date
23/09/2019 19:14
Last modification date
24/03/2020 7:20
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