Persistence of transferred fragrance on fabrics for forensic reconstruction applications.

It has recently been established that volatile organic compounds (VOCs) successfully transfer between clothing even with a short contact of 10 s, highlighting the potential to use VOCs in forensic reconstruction scenarios, such as sexual assault cases. The mid and low volatility compounds transferred in greater amounts than high volatility compounds. This study presents empirical data addressing the persistence of transferred VOCs on clothing for the first time. A series of experiments were carried out to determine the persistence of VOCs on clothing for time periods of up 4 weeks, on natural and synthetic fibres, and at three different environmental temperatures. The data indicate that the highest VOC amounts are generally obtained for shorter persistence times of up to 1 d. Whilst high volatility compounds were not recovered in sufficient amounts to allow quantification, the four other transferred VOCs were successfully quantified for persistence times of up to 4 weeks. The persistence for mid-volatility compounds follows decay curve trends in line with those previously obtained for fibres, glass and pollen. When comparing the persistence of VOCs on a natural and a synthetic fibre, for a persistence time of 1 h, the transferred VOCs were retained on a natural fibre in higher amounts than on a synthetic fibre. However, for longer persistence times the concentration of VOCs was similar between the two fabrics. Lastly, lower environmental temperatures resulted in higher recoveries for most VOCs, especially for short persistence times. These findings demonstrate that optimal recovery of VOCs from clothing occurs when the fabric is kept at cooler temperatures and analysed soon after the fragrance transfer occurred, although VOC recovery was possible at higher temperatures and after longer persistence times. Given the transfer and persistence characteristics of VOCs from fragrance, there is potential for fragrance to be used as a form of trace in forensic reconstruction approaches.

Fragrance transfer between fabrics for forensic reconstruction applications.

Sexual assault is a serious crime that often has low conviction rates. Recent literature has demonstrated that there is potential for fragrances to be valuable in forensic reconstructions where there has been contact between individuals. However, developing appropriate evidence bases for understanding the nature of fragrance transfer in these contexts is needed. This article presents three experiments that address the transfer process of fragrances that have been transferred from a primary piece of fabric onto a secondary piece of fabric, in a manner that could occur during an assault. The three variables studied were the ageing time of the fragrances on the first fabric prior to transfer, the contact time between the two fabrics, and lastly the fabric type (of the primary material and the recipient material). The transfer was evaluated using a validated solid phase micro-extraction gas chromatography-mass spectrometry (SPME GC-MS) method. The findings demonstrated that all three variables had an impact on the transfer of fragrances between clothing fabrics. Generally, lower volatility compounds were transferred and recovered in larger amounts than higher volatility compounds. All fragrance compounds were successfully recovered from a secondary piece of fabric even when the contact time was as short as 10 s, and even when the perfume was aged on the primary fabric for as long as 48 h. The nature of the fragrance transfer also depended on the fabric type, so that a clear discrimination was observed between the fragrance transfer that occurred onto a natural fabric (cotton) and onto a synthetic fabric (polyester).

Determination of Calystegines in Several Tomato Varieties Based on GC-Q-Orbitrap Analysis and Their Classification by ANOVA.

In this study, several calystegines (A3, A5, B1, B2, B3, B4, and C1) were determined in tomato. A simple extraction followed by a derivatization step with silylating agents was performed prior to their analysis by gas chromatography coupled to high resolution mass spectrometry (GC-HRMS-Q-Orbitrap), which allowed the monitoring of several ions at accurate mass. The validation of the method has provided suitable values of linearity, trueness (73.7-120.0%), and precision (≤20.0%, except for calystegines B3 and B4 at 0.5 mg/kg). The limit of quantitation was set at 0.5 mg/kg for all analytes. The validated method was successfully applied to the analysis of nine different tomato varieties, and calystegines A3, A5, B2, and C1 were found at concentrations ranging between 0.65 mg/kg (C1) and 12.47 mg/kg (B2). Tomato varieties were classified according to their calystegines content by applying an analysis of variance (ANOVA).

Development of a HS-SPME/GC-MS method for the analysis of volatile organic compounds from fabrics for forensic reconstruction applications.

An analytical method for the determination of trace amounts of volatile organic compounds (VOCs) relevant to the cosmetics industry was optimised, validated and employed for the analysis of commercial perfumes. The method used a combination of headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). In addition to fibre type, three different HS-SPME extraction conditions were investigated simultaneously, namely incubation time, extraction time and extraction temperature, using a central composite design in order to determine the optimal conditions for the extraction of VOCs of interest. The main figures of merit of the proposed method (calibration range, limits of detection and quantification, trueness and precision) were evaluated for six different VOCs in both natural and synthetic fibres in order to validate it and verify its capability for the proposed application. The validated method was applied for the analysis of traces of commercial perfumes from fabrics, and the VOCs of interest were successfully quantified. This simple, highly sensitive, and robust method has the potential to represent a powerful approach for forensic reconstructions where perfumes have transferred between individuals, such as during assaults and sexual assaults.

Rum classification using fingerprinting analysis of volatile fraction by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry.

In this study, targeted and untargeted analyses based on headspace solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) method were developed for classifying 33 different commercial rums. Targeted analysis showed correlation of ethyl acetate and ethyl esters of carboxylic acids with aging when rums of the same brand were studied, but presented certain limitations when the comparison was carried out between different brands. To overcome these limitations, untargeted strategies based on unsupervised treatments, such as hierarchical cluster analysis (HCA) and principal component analysis (PCA), as well as supervised methods, such as linear discriminant analysis (LDA) were applied. HCA allowed distinguishing main groups (with and without additives), while the PCA method indicated 40 ions corresponding to 13 discriminant compounds as relevant chemical descriptors for the correct rum classification (PCA variance of 88%). The compounds were confirmed based on the combination of retention indexes and low and high-resolution mass spectrometry (HRMS). Using the obtained results, LDA was carried out for the analytical discrimination of the remaining rums based on manufacturing country, raw material type, distillation method, wood barrel type and aging period and 94%, 91%, 92%, 95% and 94% of rums, respectively, were correctly classified. The proposed methodology has led to a robust analytical strategy for the classification of rums as a function of different parameters depending on the rum production process.