title: The effect of environmental conditions on the persistence of common lubricants on skin for cases of sexual assault investigation.
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.
authors.affiliation: Discipline of Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
authors.forename: Megan
authors.initials: M
authors.lastname: Tonkin
authors.forename: Li Foong
authors.initials: LF
authors.lastname: Yeap
authors.forename: Emma K
authors.initials: EK
authors.lastname: Bartle
authors.forename: Anthony
authors.initials: A
authors.lastname: Reeder
mesh_terms: D000818:Animals; D004780:Environment, Controlled; D049429:Forensic Pathology; D008401:Gas Chromatography-Mass Spectrometry; D005990:Glycerol / Q000032:analysis; D006801:Humans; D054327:Lubricants / Q000737:chemistry*; D023421:Models, Animal; D009821:Oils / Q000032:analysis; D011902:Rape; D012867:Skin / Q000737:chemistry*; D013472:Sunlight; D013552:Swine; D013696:Temperature
chemical_list: D054327:Lubricants; D009821:Oils; D005990:Glycerol