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Chemical Discrimination of Lubricant Marketing Types Using Direct Analysis in Real Time Time-of-Flight Mass Spectrometry

NCJ Number
Mark Maric, Lauren Harvey, Maren Tomcsak, Angelique Solano, Candice Bridge
Date Published
January 2017
9 pages
This study characterized by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) 90 personal bottled and condom lubricants from the three main marketing types; i.e., silicone-based, water-based, and condoms.
Compared to other violent crimes, sexual assaults suffer from very low prosecution and conviction rates, especially in the absence of DNA evidence. As a result, the forensic community needs to use other forms of trace contact evidence, such as lubricant evidence, in order to provide a link between the victim and the assailant. In the current study, the instrumental data were analyzed by multivariate statistics, including hierarchal cluster analysis, principal component analysis, and linear discriminant analysis. By interpreting the mass spectral data with multivariate statistics, 12 discrete groupings of lubricants were identified, indicating inherent chemical diversity not only between but within the three main marketing groups. A number of unique chemical markers, both major and minor, were identified, other than the three main chemical components (i.e. PEG, PDMS and nonoxyno 9) currently used for lubricant classification. The data were validated by a stratified 20 percent withheld cross validation, which demonstrated that there was minimal overlap between the groupings. Based on the groupings identified and unique features of each group, a highly discriminating statistical model was then developed that aims to provide the foundation for the development of a forensic lubricant database that may eventually be applied to casework. (Publisher abstract modified)
Date Published: January 1, 2017