The detection and discrimination of sunless self-tanners containing dihydroxyacetone on clothing using instrumental techniques
Palmer, Emily Jayne
MetadataShow full item record
The awareness of health risks associated with sun exposure, primarily ultra violet (UV) radiation, have played a large role in the introduction of sunless self-tanning products. These products, produced by cosmetic companies, are intended to provide the user with a sun-tanned appearance without exposing the skin to harmful UV radiation. While the manufacturers of these products claim that the products are transfer-free, several reports of the tanner depositing onto the wearers clothing have been documented1. As this is a highly undesirable characteristic for the consumer, the product's ability to transfer onto clothing makes sunless self-tanners a potentially valuable piece of forensic evidence in cases where an altercation between two individuals has occurred, specifically in sexual assaults, beatings, and homicides. The presence of self-tanner on an individual's clothing could help corroborate a story and provide an additional piece of evidence and/or leads to an investigation. The purpose of this study was to determine if sunless self-tanners transfer from skin to clothing. Given that a transfer occurs, this research was also intended to both identify and evaluate the differences seen between self-tanning products using instrumental techniques that would typically be used in forensic labs. Sixteen sunless self-tanning products were added to the skin as directed by the manufacturer. After an assigned time interval since application (15 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, or 12 hours) was reached, a white cotton swatch was used to wipe a portion of the sunless self-tanner off of the skin in attempt to simulate a realistic scenario of an altercation between individuals who may be wearing the product. Observations of the cotton swatches were document. Transferred material on the cotton swatches was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). Analysis of the products prepared directly from the packaging as well as two samples containing transferred material were analyzed using Gas Chromatography- Mass Spectrometry (GC-MS). All of the sixteen samples tested transferred from the skin onto the cotton swatch when forcibly wiped at each time interval. FTIR analysis was unable to discriminate between the commercial products but was able to separate the samples into six groups based on similarities seen between the spectra. Analysis using this instrumental technique was useful in identifying the samples as sunless self-tanning products, but was unable to differentiate further. Analysis of the sunless self-tanners prepared directly from their packaging/bottle using GC-MS was able to differentiate between the products, providing a combination of chemical ingredients that were unique to each product. Analysis of the transferred material on the cotton swatches did not identify all of the chemical components that were earlier considered unique to that sample, however, peaks were observed in the chromatogram that were also present in the samples when prepared directly from their packaging. These transferred samples were able to be identified when a known sample was available for comparison. The instrumental techniques used in this study are useful in analyzing and identifying suspected sunless self-tanner stains on clothing in a crime laboratory setting. The results obtained from this analysis can provide probative information in an investigation.