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The Effect of Environmental Conditions on the Persistence of Common Lubricants on Skin for Cases of Sexual Assault Investigation

Authors

  • Megan Tonkin M.Pharm.,

    1. Discipline of Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA, Australia
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  • Li Foong Yeap M.Pharm.,

    1. Discipline of Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA, Australia
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  • Emma K. Bartle Ph.D.,

    Corresponding author
    1. Centre for Medical Education Research and Scholarship, School of Medicine, The University of Queensland, Herston, Qld, Australia
    2. Discipline of Chemistry, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA, Australia
    • Discipline of Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA, Australia
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  • Anthony Reeder Ph.D.

    1. Discipline of Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, WA, Australia
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  • This research was supported by The University of Western Australia.

Additional information and reprint requests:

Emma K. Bartle, Ph.D.

School of Medicine

The University of Queensland

288 Herston Road

Herston, Qld 4006

Australia

E-mail: e.bartle@uq.edu.au

Abstract

The potential for lubricant trace evidence to be used as associative evidence is often overlooked in forensic investigations. Published studies in this area have focused on the identification of analytical techniques suitable for the detection of this evidence type. However, detection of trace lubricant is also dependent on the length of time it persists on skin and mucosal surfaces. The objective of this study was to investigate the effect of environmental conditions on the persistence of oil- and glycerol-based lubricants on skin surfaces. Lubricated skin samples exposed to three different test environments were swabbed at regular intervals over a 24-h period. Compounds of interest were extracted from the swabs and analyzed using gas chromatography–mass spectrometry (GC-MS). The effect of glycerol derivatization prior to GC-MS analysis was also investigated. In general, oil-based lubricants persisted longer than glycerol-based. Persistence on skin was greatest in lower temperature conditions away from direct sunlight exposure. The results of this investigation are relevant in the context of sexual assault investigations given the possible detection of lubricant on the skin of the external genitalia.

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