Analysis of transferred fragrance and its forensic implications

Abstract

At present, the analysis of volatile organic compounds (VOCs) from fragrances is not employed in forensic science despite its potential as a form of trace evidence. Perfumes are used by many men and women on a daily basis, contain a large and diverse number of fragrances, and are invisible to the naked eye. Moreover, research on VOCs from human scent has shown that solid phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is a robust method for the analysis of these odorous compounds. This enables insights into the transfer and persistence of the VOCs, which is a prerequisite for the use of a trace in forensic reconstructions. This thesis presents the development, optimisation, and validation of a SPME GC-MS method for quantification of VOC traces from clothing. The method created was robust and sensitive, allowing quantification of VOCs from clothing even when the fragrance mixture was diluted up to 1500 times. Experiments that addressed the transfer characteristics of fragrance VOCs demonstrated that fragrances can transfer from one fabric to another even when the contact times between fabrics is as short as 10 s, and even when the perfume was aged on the primary fabric for as long as 48 h before transfer took place. The nature of the fragrance transfer also depended on the fabric type, so that a clear discrimination was observed between the transfer that occurred from a cotton fabric swatch onto a natural (cotton) fabric and onto a synthetic (polyester) fabric. Further experiments considered the persistence of fragrances. The data generated indicate that the highest VOC amounts are generally obtained from recipient fabrics after shorter persistence times of up to 1 d, however VOCs were successfully quantified for persistence times of up to 4 weeks. Lower environmental temperatures resulted in higher recoveries for most VOCs, especially for short persistence times. These findings demonstrate that the optimal recovery of VOCs from clothing occurs when the fabric is kept at cooler temperatures and analysed soon after the fragrance transfer occurred. Therefore, given the ability to recover VOCs from fragrances from clothing, and the transfer and persistence characteristics of these VOCs, there is potential for fragrance to be used as a form of trace in forensic reconstruction approaches to address both source and activity level propositions

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