Assessing the potential fire risk of laundered fabrics after contamination with emollients using ATR-FTIR spectroscopy and chemometrics.

Since 2010, more than 50 UK fire deaths, have been reported as linked with emollients. This prompted the Medicines and Healthcare products Regulatory Agency (MHRA) to issue advice on their safer use in 2018. The advice was in response to concerns raised by the National Fire Chiefs Council, coroners' reports, and flammability tests. The test results show a significant reduction in ignition time of fabrics contaminated with paraffin-based and paraffin-free skin care product residues. The MHRA report also included advice on washing clothing and bedding at high temperatures but warned this may not remove all emollient residues. This paper reports on new research on the removal of skin care products from clothing investigated by laundering contaminated 100% cotton fabric at 30, 40 and 60 °C using both biological and non-biological based detergents. As part of the experiment, non-contaminated (blank) napkin samples were included in the wash experiments to assess the possible transfer from fabrics contaminated with emollients to uncontaminated clean fabrics during washing. Washed and dried fabrics were analysed using Attenuated Total Reflectance, Fourier Transform Infrared (ATR-FTIR) spectroscopy and further interpreted via principal component analysis (PCA) and network analysis. Results suggest that the majority of the 6% white soft paraffin-based lotion and paraffin-free cream were removed at all temperatures. Residues of 21% paraffin-based cream (6% light paraffin/15% white soft paraffin) remain, and more residues persist of the 100% paraffin-based ointment (5% light paraffin/95% white soft paraffin) after washing at 30, 40 and 60 °C. The wash experiments show unequivocal transfer of the 100% ointment from the contaminated napkins to clean control napkins placed within washes at 30 °C. Furthermore, residues of the ointment were observed within the machine drum, and washing machine door seal, though this did not cause secondary transfer to subsequent wash experiments. There were no differences observed when using biological versus non-biological detergents, nor when employing a pre-wash treatment in the removal of residues of the 21% cream and 100% ointment. These results suggest that a single application of an emollient when soaked and dried into a fabric is not removed by a single wash at 30, 40 or 60 °C. Instead, the residue remains a persistent potential fire risk and, its high paraffin content presents an additional fire risk via contamination of other fabrics.

The effect of paint type on the development of latent fingermarks on walls.

Despite recent advances in DNA technology, fingermark evidence remains a fundamental method of ascertaining an individual's identity. Latent fingermarks are the commonest type of fingermark encountered at crime scenes. The Fingermark Visualisation Manual provides crime scene practitioner's with sequential information regarding which enhancement processes are best suited for a range of deposition surfaces (Bandey et al., 2014) [1]. However, there are still many surfaces, such as painted walls where more knowledge is required regarding which development techniques provide optimum results. In this study, four paint types were tested (matt, silk, bathroom and eggshell). Fingermarks were deposited on painted simulated walls and aged for 1 day, 1 week and 1 month. Fingermarks were developed by three processes highlighted as the most frequently used by practitioners (magnetic granular powder, magneta flake powder and ninhydrin). The results showed that overall black magnetic granular powder outperformed both magneta flake powder and ninhydrin on all paint types. This contradicts current UK guidelines for enhancement of fingermarks on matt painted walls, as black magnetic granular powder is not a recommended process at present. SEM and SEM-EDX analysis showed distinct differences between matt paint and the three non-matt paints tested, which provides an explanation for the results obtained.

Efficiency of the dry-wet method for the MALDI-MSI analysis of latent fingermarks.

Matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) has proven to be a powerful analytical tool to investigate problems in several fields of life science. A novel application is in the field of forensics, particularly in the analysis of latent fingermarks. This technology enables images of the fingermark ridge detail and additional intelligence to be simultaneously obtained. Although several methods are available to deposit the MALDI matrix, to make the technology forensically operational, another deposition approach was devised and reported, namely the 'dry-wet' method. In the present study, the efficiency of the dry-wet method was evaluated and compared with the conventional spray coat methodology. Results indicate that the dry-wet method is superior for all the donors' typologies in terms of ion signal intensity and clarity of the ridge details. To underpin the reasons of this efficiency, scanning electron microscopy analyses were carried out in parallel to MALDI-MSI experiments using matrices of different particle size. Results have confirmed that the particle size plays an important role in the efficiency of the method as higher quality images and higher intensity spectra are produced as the matrix particle size decreases.

Spectroscopic imaging based approach for condom identification in condom contaminated fingermarks.

Sexual offenders are increasingly reported to use condoms while committing the crime, mainly to prevent the transfer of DNA evidence. Although condoms are often removed from the crime scene, vaginal swabs can be taken from the victim to prove the presence of condom lubricants and therefore evidence of corpus delicti. However, late reporting to the police and the tendency of the victim to wash immediately after the crime, may compromise the detection of condom lubricants. Recently we showed that Matrix-Assisted Laser Desorption/Ionisation MS Imaging (MALDI MSI) of condom contaminated fingermarks enables images of the fingermark ridge pattern to be obtained simultaneously with the detection of the condom lubricant for two condom brands, thus becoming a potential alternative way to link the assailant to the crime. Building on the value of this information, it would be advantageous to identify the condom brand used during the sexual assault. Here we show the development of a multidisciplinary spectroscopic approach, including MALDI MSI, MS/MS, Raman microscopy and ATR-FTIR spectroscopy, applied to a range of condom brands/types. The techniques have complementary features and provide complementary information to retrieve a "condom brand spectroscopic fingerprint". Unique spectroscopic profiles would greatly aid in the screening and identification of the condom, thus adding intelligence to the case under investigation.

Direct detection of peptides and small proteins in fingermarks and determination of sex by MALDI mass spectrometry profiling.

Matrix Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI MS) can detect and image a variety of endogenous and exogenous compounds from latent fingermarks. This opportunity potentially provides investigators with both an image for suspect identification and chemical information to be used as additional intelligence. The latter becomes particularly important when the fingermark is distorted or smudged or when the suspect is not a previously convicted offender and therefore their fingerprints are not present in the National Fingerprint Database. One of the desirable pieces of intelligence would be the sex of the suspect from the chemical composition of a fingermark. In this study we show that the direct detection of peptides and proteins from fingermarks by MALDI MS Profiling (MALDI MSP), along with the multivariate modeling of the spectra, enables the determination of sex with 85% accuracy. The chemical analysis of the fingermark composition is expected to additionally provide information on traits such as nutritional habits, drug use or hormonal status.

Chemical characterization of latent fingerprints by matrix-assisted laser desorption ionization, time-of-flight secondary ion mass spectrometry, mega electron volt secondary mass spectrometry, gas chromatography/mass spectrometry, X-ray photoelectron spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopic imaging: an intercomparison.

The first analytical intercomparison of fingerprint residue using equivalent samples of latent fingerprint residue and characterized by a suite of relevant techniques is presented. This work has never been undertaken, presumably due to the perishable nature of fingerprint residue, the lack of fingerprint standards, and the intradonor variability, which impacts sample reproducibility. For the first time, time-of-flight secondary ion mass spectrometry, high-energy secondary ion mass spectrometry, and X-ray photoelectron spectroscopy are used to target endogenous compounds in fingerprints and a method is presented for establishing their relative abundance in fingerprint residue. Comparison of the newer techniques with the more established gas chromatography/mass spectrometry and attenuated total reflection Fourier transform infrared spectroscopic imaging shows good agreement between the methods, with each method detecting repeatable differences between the donors, with the exception of matrix-assisted laser desorption ionization, for which quantitative analysis has not yet been established. We further comment on the sensitivity, selectivity, and practicability of each of the methods for use in future police casework or academic research.

A novel matrix-assisted laser desorption/ionisation mass spectrometry imaging based methodology for the identification of sexual assault suspects.

An increase in the use of condoms by sexual offenders has been observed. This is likely to be due both to the risk of sexually transmitted diseases and to prevent the transfer of DNA evidence. In this scenario the detection of condom lubricants at a crime scene could aid in proving corpus delicti. Here we show a novel application of Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) for mapping the fingermark ridge pattern simultaneously to the detection of the condom lubricant within the fingermark itself. Two condom brands have been investigated to prove the concept. Condoms were handled producing lubricant-contaminated fingermarks. Images of the ridge pattern were obtained simultaneously to the detection of two lubricants, even several weeks after the fingermark deposition. The results therefore show the potential of MALDI MSI to link the suspect (identification through fingermark ridge pattern) to the crime (detection of condom lubricant) in one analysis. This would enable forensic scientists to provide evidence with stronger support in alleged cases of sexual assault.