Analysis of condom evidence in forensic science: Background survey of the human vaginal matrix using DRIFTS and pyrolysis-GC/MS. (April 2021)

• Record Type: Journal Article
• Authors: Hermelin, Anaïs; Fabien, Loïc; Fischer, Julia; Saric, Nikola; Massonnet, Geneviève; Burnier, Céline
• Is Part Of: Forensic science international. Volume 321(2021)
• Publication Date: 2021-04
• Subjects: PCA -- Chemometrics -- Forensic -- Background -- Interpretation; Medical jurisprudence -- Periodicals; Chemistry, Forensic -- Periodicals; Forensic Medicine -- Periodicals; Médecine légale -- Périodiques; Chimie légale -- Périodiques; Gerechtelijke geneeskunde; Gerechtelijke chemie; Gerechtelijke psychiatrie; Chemistry, Forensic; Medical jurisprudence; Electronic journals; Periodicals; Electronic journals; 614.1
• DOI: 10.1016/j.forsciint.2021.110724
• Languages: English
• ISSNs: 0379-0738

Abstract

Abstract: Condom traces are increasingly detected from victims of sexual assault, mostly from vaginal swabs. Protocols have been developed for the analysis of silicone-based condom lubricants using DRIFTS-FTIR and py-GC/MS, but very little research is concerned with the background contribution of the vaginal matrix itself. The present contribution would be an asset for more fundamental research on condom residues in the vaginal matrix, as well as for interpretative purposes in the forensic area. This study investigated vaginal matrix residues using Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS-FTIR) and pyrolysis Gas-Chromatography coupled to Mass Spectrometry (py-GC/MS) to obtain fundamental information about the vaginal matrix's initial composition. Differences between women of a given population were investigated as well as the prevalence of silicone-based residues for natural purposes in the population. Apolar fractions of the samples were investigated after extraction with hexane, as it is the one targeted for silicone-based lubricants used in condoms. Infrared spectroscopy outlined the presence of various proteins and lipids in all the samples, and the spectral regions 1000–1850 cm −1 and 2700–3600 cm −1 were identified as the most relevant zones of the spectra. Pyrolysis-GC results confirmed the presence of lipids, more specifically the presence of cholesterol residues. Chemometrics analyses showed that it was not possible to distinguish the samples based on the qualitative nor semi-quantitative content. This suggest that the same type of compounds are extracted regardless of the donor. None of the samples were found to contain any silicones residues. These results are promising from a forensic evidence interpretation perspective. Further research is required to fully validate such models and assess their robustness and limitation in casework conditions. Highlights: The apolar fraction of the human vaginal matrix exhibits a high degree of complexity. Most informative FTIR spectral region was found to be between 700 and 1850 cm −1 and 2700–3600 cm −1 . 27 compounds were detected using py-GC/MS. Traces of silicone detected via FTIR in 7% of the samples were not confirmed by py-GC/MS. Several uncontrolled factors could affect the sample and were not initially monitored.