Vibrational spectroscopic techniques have shown to be highly suitable for the identification and comparison of textile fibres and clothing fabrics. On the other hand, new chemical imaging modes based on these spectroscopic techniques are becoming useful in multiple fields. This is particularly important to, for instance, chemically visualize and screen different samples including forensic evidence (crime scene investigation), chemical and food products (quality control), biological tissues and living beings (medical imaging), among others. This study explores the forensic examination and selective chemical visualization of textile fibres and clothing fabrics using Raman imaging. Four experiments were performed, which were focused on the screening of (i) white different materials made of 100 % cotton (gauze, cotton wool, t-shirt, and swab), (ii) polyester and cotton fabrics evidence of the same colour, (iii) five different coloured cotton fabrics, and (iv) textile fibres of different materials (acrylic, cotton, nylon, polyester, and silk). Several methods of multivariate chemometric analysis including principal component analysis (PCA), multivariate analysis of variance (MANOVA), and multivariate curve resolution (MCR) were applied to enhance the limited visual comparison of the spectra accomplished with the unaided eye. The results evidenced the suitability of Raman imaging to statistically discriminate textile fibres and fabrics due to the chemical composition of both the clothing material and the dyestuff.

This work comprehensively reviews some fundamental concepts about explosives and their two commonly used classifications based on either their velocity of detonation or their application. These classifications are highly useful in the military/legal field, but completely useless for the chemical determination of explosives. Because of this reason, a classification of explosives based on their chemical composition is comprehensively revised, discussed and updated. This classification seeks to merge those dispersed chemical classifications of explosives found in literature into a unique general classification, which might be useful for every researcher dealing with the analytical chemical identification of explosives. In the knowledge of the chemical composition of explosives, the most adequate analytical techniques to determine them are finally discussed.

In post-mortem (PM) investigations, forensic toxicologists attempt to identify legal or illegal substances present before death and determine how they contributed to the cause of death. A critical challenge is ensuring that PM sample concentrations accurately reflect those at the time of death, as postmortem redistribution (PMR) can alter these levels due to anatomical and physiological changes. The PMR phenomenon is called a ‘toxicological nightmare’. PMR significantly affects post-mortem drug concentrations, particularly for lipophilic drugs and those with a high volume of distribution. The emergence of new psychoactive substances (NPSs) has led to a growing recognition of their role as a significant public health concern, frequently associated with fatalities related to polydrug use. These substances are renowned for their ability to induce intoxication at low doses, which has led to the continuous updating of toxicological and forensic methods to improve detection and adopt new analytical standards. The comprehensive detection of NPS metabolites, some of which are still undiscovered, presents an additional analytical challenge, as do their metabolic pathways. This complicates their identification in fatal cases using standard analytical methods, potentially leading to an underestimation of their actual prevalence in toxicological results. Furthermore, the interpretation of analytical results is hindered by the absence of data on PM blood levels and the specific contributions of NPS to causes of death, exacerbated by the lack of knowledge of whether the PMR phenomenon influences them. This paper presents a comprehensive review of the literature on post-mortem cases involving various NPS, categorized according to classifications by the United Nations Office on Drugs and Crime (UNODC) and the European Union Drugs Agency (EUDA). These categories include cathinones, phenylethylamines, arylalkylamines, phencyclidine-type substances, phenmetrazines, piperazines, phenidates, aminoindanes, LSD-like NPSs, tryptamines, fentanyl analogs, designer benzodiazepines, synthetic cannabinoids, and nitazenes. This review covers not only postmortem blood levels but also the stability of the substances studied, the methods of analysis, and attempts to shed some light on the PMR phenomenon. This review used various key terms, such as PMR, NPS, and the names of previously categorized substances and drug analyses across multiple peer-reviewed journals and databases, including Scopus, Google Schoolar, Springer, PubMed, and Wiley Online Library. In addition, references from retrieved articles were examined to identify additional relevant research. Interpreting post-mortem toxicological results is complex and lacks definitive guidelines, requiring a nuanced understanding of its challenges and potential pitfalls. As a result, post-mortem toxicology is often regarded as an art. The primary aim of this review is to provide forensic toxicologists with a comprehensive framework to assist in the evaluation and interpretation of NPS analysis. This guide is intended to complement the existing knowledge and practices applied in forensic laboratories within the toxicological analysis of post-mortem cases.

Few studies have reported the prevalence or incidence about the consumption of new psychoactive substances (NPS). The hair analysis can be useful for this purpose. At the present, ketamine is the most consumed arylcyclohexylamine associated to young consumers and polyconsumption profiles. For this reason, ketamine consumer cases become very interesting to provide information on NPS prevalence. In this work, ten former cases of the National Institute of Toxicology and Forensic Science (INTCF) of Madrid Department (INTCFM), all of them belonging to defendants accused of crimes against public health and who had been found positive to ketamine, were reassessed. At the first toxicological analysis of those hair samples, a positive consume in ketamine had been determined by gas chromatography coupled to mass spectrometry (GC-MS). In this work, the same hair samples were reanalyzed by high-resolution mass spectrometry ( UHPLC-HRMS/MS) using an incubation methanolic extraction combined with a single, simpler, non-selective and direct sample pre-treatment. After corroborating the GC-MS results previously obtained for the same samples, the detection of additional NPS using this new methodology evidenced its benefits and opened the possibility to perform a NPS prevalence study. In brief, in those cases with a positive consumption in ketamine, a polyconsumption of other drugs and NPS was found, including different arylcyclohexylamines as deschloroketamine, 3-MeO-PCP and methoxetamine; and cathinones as methylmetcathinone and N-ethyl-pentylone.