The analysis of lubricant evidence is a recent development in sexual assault investigations, and in the absence of any biological evidence may assist in linking an assailant to the victim or crime scene. Since lubricants are complex multicomponent mixtures, this study Examined whether different thermal desorption temperatures could elucidate different additives and provide additional information. A low-temperature, high-temperature, and thermal desorption/pyrolysis DART-MS protocol was used to characterize the water-based lubricant sample set. The strength of the methodologies was assessed using positive and negative likelihood ratios that were calculated from inter- and intra-pairwise comparisons using Pearson correlation coefficients. The low-temperature DART-MS protocol afforded valuable information pertaining to volatile additives (e.g., flavors and fragrances) and provided positive likelihood ratios that would provide strong support for true positive and negatives than the high-temperature protocol when associating between individual samples and samples to their respective sub-groupings. The thermal desorption/pyrolysis DART analytical protocol provided enhanced differentiation between samples due to the precise temperature control using a thermal gradient. Moreover, the total ion spectra obtained from the thermal desorption/pyrolysis protocol had high positive and negative likelihood ratios, as well as the most discrimination, as determined by empirical cross entropy plots. (publisher abstract modified)
Temperature-Dependent DART-MS Analysis of Sexual Lubricants to Increase Accurate Associations
NCJ Number
254176
Journal
Journal of the American Society for Mass Spectrometry Volume: 30 Issue: 8 Dated: 2019 Pages: 1343-1358
Date Published
2019
Length
16 pages
Annotation
This study used an ambient ionization technique, high-resolution direct analysis in real-time mass spectrometry (HR-DART-MS) to characterize a sample set of 33 water-based sexual lubricants.
Abstract