The use of an optimized DRIFTS-FTIR method for the forensic analysis and classification of silicone condom lubricants

Forensic Discrimination of condom lubricants using ATR-FTIR spectroscopy in combination with chemometrics- effect of matrices, pre-coital and post-coital conditions

The escalating rates of rape and sexual assault cases underscore the essential need to analyze associative evidence of sexual assault to ensure justice. The condom, when used during the act of sexual assault/rape, leaves behind traces of lubricant that could be instrumental in establishing the link between the victim and perpetrator. This leading evidence is crucial especially when the traditional DNA analysis is challenging owing to the lack of biological evidence. The present study employs the use of ATR FTIR spectroscopy coupled with the chemometric, to discern the chemical discrimination of condom lubricants. The study also aimed to investigate simulated real-case scenarios by analysing the effect of different matrices such as vaginal fluid, menstrual blood, and undergarment substrates (cotton, polyester and nylon) on condom traces. The difference in the spectral profile of pre-coitus and post-coitus samples was also investigated. The results of the present study are noteworthy, unveiling the efficacy of discriminating the condom lubricants of different brands and other frequently used household lubricants with 100% sensitivity, specificity, and accuracy. Condom lubricants are detected despite the presence of contaminants such as menstrual blood, and vaginal fluid, across different substrates and, in post-coital conditions. In conclusion, this study presents a comprehensive approach to analysing condom lubricants, offering a potential breakthrough in the investigation of sexual assault cases, coupled with the ability to counter false accusations.

Forensic aspects of condom evidence: Analysis, interpretation, and recent trends

In recent years, collection and analysis of condom evidence in sexual assault investigations are becoming more common in forensic caseworks. Condom analysis can provide investigative leads or establish potential contact between the suspect and victim in the absence of DNA evidence or supplement biological evidence. Recent forensic literature shows significant advancements in the analysis of condom lubricants, including casework samples. There is an increasing trend in the use of chemometric tools for the comparison and interpretation of the results. This review highlights the advances in common analytical techniques used for the analysis of condom lubricants with a particular focus on the developments occurring in recent years, including chemometric interpretation. The analysis of reference and casework samples (swab samples, samples on skin, clothing and fingermark) are discussed separately. For casework samples, the transfer and persistence of different lubricant formulations are discussed, along with their detection with various analytical approaches. The issues with the interpretation of lubricants are also discussed in another section, with particular emphasis on samples such as personal hygiene products which have similar formulations with sexual lubricants and the interpretation of negative profiles. The current challenges in the field and prospects for future research are also discussed.

LMJSSP for analysis of prophylactic lubricants, spermicides and residues

DNA evidence in sexual assault cases have proven increasingly difficult to obtain and analyse due to increased condom use. With more interest in alternatives to DNA evidence, prophylactic lubricants, spermicides and residues may be interesting prospects. Current interest in the analysis of prophylactic residues focuses on the evaluation and identification of lubricants and constituents, primarily through gas chromatography or Fourier transform infrared spectroscopy. Though cost-effective methods, extensive sample preparation and destructive modes of analysis remain an area for improvement. As a result, the focus has since shifted to ambient ionization methods that offer adequate sensitivity and reduced sample preparation. The Liquid Microjunction Surface Sampling Probe (LMJSSP) is a versatile ambient ionization source that employs a probe that supports a continuously flushing droplet that extracts analytes when placed in contact with a surface. The analytes are aspirated into the mass spectrometer with a Venturi pressure. In this work we use the LMJSSP to analyse the trace transfer of condom lubricant to different types of fabric (cotton, cotton-spandex, and denim). Furthermore, we examine the sensitivity and storage conditions for the direct analysis method on different swab types (cotton, silicone, and foam). Additionally, Principal Component Analysis (PCA) and Maximally Collapsing Metric Learning (MCML) are utilized for visualization of differentiability of commercially available condom brands including Durex™ and Trojan™, and product subtypes. The results present an interesting multi-disciplinary approach of using a direct liquid extraction ambient ionization technique and machine learning to improve the overall workflow for the analysis of lubricants, swabs and fabrics. Machine learning algorithms were able to differentiate between inherent differences of Durex™ and Trojan™ condoms.

The Analytical Possibilities of FT-IR Spectroscopy Powered by Vibrating Molecules

This paper discusses the state of advancement in the development of spectroscopic methods based on the use of mid (proper) infrared radiation in the context of applications in various fields of science and technology. The authors drew attention to the most important solutions specific to both spectroscopy itself (ATR technique) and chemometric data processing tools (PCA and PLS models). The objective of the current paper is to collect and consistently present information on various aspects of FT-IR spectroscopy, which is not only a well-known and well-established method but is also continuously developing. The innovative aspect of the current review is to show FT-IR's great versatility that allows its applications to solve and explain issues from both the scientific domain (e.g., hydrogen bonds) and practical ones (e.g., technological processes, medicine, environmental protection, and food analysis). Particular attention was paid to the issue of hydrogen bonds as key non-covalent interactions, conditioning the existence of living matter and determining the number of physicochemical properties of various materials. Since the role of FT-IR spectroscopy in the field of hydrogen bond research has great significance, a historical outline of the most important qualitative and quantitative hydrogen bond theories is provided. In addition, research on selected unconventional spectral effects resulting from the substitution of protons with deuterons in hydrogen bridges is presented. The state-of-the-art and originality of the current review are that it presents a combination of uses of FT-IR spectroscopy to explain the way molecules vibrate and the effects of those vibrations on macroscopic properties, hence practical applications of given substances.

On the impact of DNA extraction procedure on the recovery of condom evidence

On the international level, different protocols exist for sampling condom traces, similarly to DNA traces. Usually collected with cotton swabs, some protocols use nylon swabs, which were found more efficient for the desorption of DNA, because they offer a better desorption of the compounds during the extraction. In addition, not all the protocols do contain swabs for other evidence than DNA. Depending on the protocol, the forensic scientist will either benefit from a swab purely dedicated to condom evidence or will have to prioritize which evidence to analyse first. It is more likely that priority will be set to DNA, but in the eventuality that no DNA would be recovered, it is necessary to know whether the swab can still be used for condom evidence recovery or not. This work aimed to use Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS-FTIR) to investigate whether DNA extraction affects the recovery of condom traces. Traces were simulated by either rubbing condoms on the swabs or soaking the swabs in solutions containing different concentrations of polydimethylsiloxane (PDMS), the most common condom lubricant found on the market. DNA extraction was found to generate a loss of silicones, when processed prior to condom silicone extraction. Therefore, results show that protocols should contain cotton swabs dedicated to condom traces collection.

A preliminary investigation of underwear as a support for condom evidence in rape and sexual assault cases

Condom lubricants have been found to be a new type of evidence to investigate and analyze in sexual assaults and rape cases. Casework studies highlighted two main types of trace evidence supports collected from the victim and send to forensic laboratories: cotton swabs and victims' underwear. If cotton swabs have been used in most of the recent published research papers, the underwear and the textile effects on the recovery of condom lubricants are under investigated although such studies are very important for the interpretation of the evidence, as highlighted in the Regina v. Andrew Nicholas Malkinson case. This work employed Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS-FTIR) and Attenuated Total Reflectance (ATR-FTIR) to investigate the content of various feminine underwear and the effect of a laundry procedure on the recovery of any type of evidence. 7 laundry detergents and 9 slips from common brands/models were purchased for this study. No silicones were detected in the laundry detergents, which indicates they are unlikely to generate false positive in terms of detection of silicones. However, silicones were detected in most of the brand new underwear, which was found to be an issue when interpreting the evidence. The laundry procedure was found to significantly affect the evidence, with a strong decrease of the absorbance pre and post washing. Unfortunately, no trend regarding the temperature or the type of textile could be drawn.