Investigating TNT loss between sample collection and analysis.

Explosives residues are often collected from explosion scenes, and from surfaces suspected of being in contact with explosives, by swabbing with solvent-wetted cotton swabs. It is vital that any explosives traces present on the swabs are successfully extracted and detected when received in a laboratory. However, a 2007 proficiency test initiated by the European Network of Forensic Science Institutes (ENFSI) Expert Working Group on Explosives involving TNT-spiked cotton swabs highlighted that explosives may not always be detected from such samples. This paper outlines work performed to determine potential reasons for this finding. Cotton swabs were spiked using a solution of TNT and stored in nylon bags and glass vials for periods of 1, 2 and 4weeks. Simulated swab extracts were also prepared and investigated. The samples were stored in a freezer, or at room temperature either in the dark or exposed to daylight. Overall, the cotton swabs stored at room temperature and exposed to daylight showed a very rapid loss of TNT over time, whereas cotton swabs stored in the freezer, and all simulated swab extracts, gave high recoveries over time. These results will be of benefit for practicing forensic explosives laboratories and for persons undertaking cold-case reviews involving explosive-based samples.

Development of gas chromatography-mass spectrometry (GC-MS) and other rapid screening methods for the analysis of 16 'legal high' cathinone derivatives.

The prevalence of so-called 'legal high' drugs in forensic science drug casework has increased markedly in recent years. This has given rise to both legal and analytical challenges in the identification of these substances. The requirement for validated, reliable and rapid testing methodologies for these compounds is obvious. This work reports the analysis of sixteen synthesised cathinone derivatives encountered in casework using presumptive testing, thin layer chromatography and gas chromatography-mass spectrometry (GC-MS).

Comparison of swabbing and cutting-out DNA collection methods from cotton, paper, and cardboard surfaces.

Choosing an inappropriate method of sample collection can often have a detrimental impact on DNA recovery. Multiple studies highlight the importance of selecting the recovery method based on the type of surface the DNA sample is located on. This study aimed to investigate the efficacy of sample collection via the single cotton swabbing method in comparison to recovery directly from the material cut from the surface. The three types of surfaces included cotton, paper, and cardboard. DNA sources comprised cell-free and cellular DNA, as well as blood and saliva as examples of body fluids commonly encountered at crime scenes. The data analysis revealed that the cutting-out method resulted in higher DNA recovery from all but cardboard surfaces, making it the more efficient collection method. Despite its limitations, the cutting-out method should be considered as the DNA recovery method of choice when suitable.

Detection of anabolic-androgenic steroids in e-cigarettes seized from prisons: A case study.

The administration of new psychoactive substances (NPS), in particular synthetic cannabinoid receptor agonists (SCRAs), via e-cigarettes, within prison settings has been well publicized. This study provides an overview of five e-cigarette case samples seized from Scottish prisons between May 2022 and July 2023 where the anabolic-androgenic steroids (AASs) mestanolone and oxandrolone were identified following gas chromatography-mass spectrometry (GC-MS) analysis. These e-cigarette samples represented 2.9% of all samples containing e-cigarette cartridges (n = 170) and 9.4% of all samples found to contain AASs (n = 53) seized during the same time period. The AASs were detected in combination with other drugs, including cocaine, Δ9-tetrahydrocannabinol (Δ9-THC), SCRAs and nicotine. This represents a new and novel route of administration for AASs.

In vitro cannabinoid receptor activity, metabolism, and detection in seized samples of CH-PIATA, a new indole-3-acetamide synthetic cannabinoid.

The rapidly evolving synthetic cannabinoid receptor agonist (SCRA) market poses significant challenges for forensic scientists. Since the enactment of a generic ban in China, a variety of new compounds have emerged capable of evading the legislation by carrying new structural features. One recent example of a SCRA with new linker and head moieties is CH-PIATA (CH-PIACA, CHX-PIATA, CHX-PIACA). CH-PIATA bears an additional methylene spacer in the linker moiety between the indole core and the traditional carbonyl component of the linker. This study describes detections in 2022 of this new SCRA in the United States, Belgium, and Scottish prisons. CH-PIATA was detected once in a seized powder by Belgian customs and 12 times in Scottish prisons in infused papers or resin. The metabolites of CH-PIATA were investigated via in vitro human liver microsome (HLM) incubations and eight metabolites were identified, dominated by oxidative biotransformations. A blood sample from the United States was confirmed to contain a mixture of SCRAs including CH-PIATA via presence of the parent and at least five of the metabolites identified from HLM incubations. Furthermore, this paper evaluates the intrinsic in vitro cannabinoid 1 and 2 (CB1 and CB2) receptor activation potential of CH-PIATA reference material and the powder seized by Belgian customs by means of ß-arrestin 2 recruitment assays. Both the reference and the seized powder showed a weak activity at both CB receptors with signs of antagonism found. Based on these results, the expected harm potential of this newly emerging substance remains limited.

A synthetic fingerprint solution and its importance in DNA transfer, persistence and recovery studies.

A review of the literature on DNA transfer and persistence highlights many difficulties that are encountered when conducting research of this nature. One of the main problems highlighted repeatedly in the literature is the prevalence of inherent uncontrolled variation that accompany these studies, and in turn, the results obtained. This work aims to decrease the amount of intrinsic variability associated with DNA transfer and persistence experiments using a realistic proxy solution which is adaptable, of known composition, reproducible, and capable of being standardised. This proxy is composed of three parts: a synthetic fingerprint solution, cellular DNA, and cell free DNA. In this proof-of-concept study the proxy was tested with a small-scale DNA transfer and recovery experiment and the data obtained suggests that the use of a solution that mimics real fingerprint secretions, over an alternative (such as buffer or a body fluid), is important when working with non-donor provided trace DNA samples. This is because the DNA deposit solution likely impacts the transfer of DNA from fingers/hands to a surface as well as the ability to recover the biological material once deposited.

Evaluation of fentanyl immunoassay test strips for rapid in-situ detection of fentanyl and fentanyl analogs in seized samples and alternative matrices.

BACKGROUND: Ion mobility spectrometry is used for the rapid detection of drugs at points of security but are unable to differentiate some drugs leading to the instrument alarming for a drug not present in the sample. This can be particularly problematic for samples that alarm for fentanyl. In this study, fentanyl immunoassay strips were evaluated for use as a secondary test for fentanyl, including for the testing of alternative matrices, such as powders, e-liquids, and infused papers and textiles. METHODS: The limit of detection of fentanyl immunoassay strips was examined along with their selectivity to 18 fentanyl analogsand 72 other drugs and cutting agents. The effectiveness of the test strips at the detection of fentanyl in the presence of other drugs was examined by testing a series of concentrations of fentanyl in solution in combination with other drugs. The testing of alternative matrices was explored with laboratory prepared samples through sampling with cotton buds and extraction in water. RESULTS: The fentanyl immunoassay strips detected fentanyl at concentrations of 45 ng/mL and reacted with 16 of 18 tested fentanyl analogs with carfentanil and norfentanyl being the only analogs to not react. There was no reactivity with other drugs or cutting agents. The effectiveness of the fentanyl test strips was not reduced when fentanyl was mixed with other drugs. Fentanyl was successfully detected with high sensitivity in all alternative matrices. CONCLUSION: The fentanyl immunoassay strips were found to be an effective secondary test for fentanyl and at least 16 fentanyl analogs in seized drug samples, including when mixed with other drugs. The effectiveness of the sampling methods for alternative matrices should be further evaluated using fentanyl and fentanyl analog casework samples. The use of this method by law enforcement and other agencies should be examined to assess its effectiveness and ease of use in operational settings.

Identification of bullets fired from air guns using machine and deep learning methods.

Ballistics (the linkage of bullets and cartridge cases to weapons) is a common type of evidence encountered in criminal cases around the world. The interest lies in determining whether two bullets were fired using the same firearm. This paper proposes an automated method to classify bullets from surface topography and Land Engraved Area (LEA) images of the fired pellets using machine and deep learning methods. The curvature of the surface topography was removed using loess fit and features were extracted using Empirical Mode Decomposition (EMD) followed by various entropy measures. The informative features were identified using minimum Redundancy Maximum Relevance (mRMR), finally the classification was performed using Support Vector Machines (SVM), Decision Tree (DT) and Random Forest (RF) classifiers. The results revealed a good predictive performance. In addition, the deep learning model DenseNet121 was used to classify the LEA images. DenseNet121 provided a higher predictive performance than SVM, DT and RF classifiers. Moreover, the Grad-CAM technique was used to visualise the discriminative regions in the LEA images. These results suggest that the proposed deep learning method can be used to expedite the linkage of projectiles to firearms and assist in ballistic examinations. In this work, the bullets that were compared were air pellets fired from both air rifles and a high velocity air pistol. Air guns were used to collect the data because they were more accessible than other firearms and could be used as a proxy, delivering comparable LEAs. The methods developed here can be used as a proof-of-concept and are easily expandable to bullet and cartridge case identification from any weapon.

A ground truth data set of gas chromatography mass spectrometry (GCMS) analysed synthesised methylenedioxymethylamphetamine (MDMA).

Controlled drug samples are normally chemically analysed to determine their identity and in some cases, their purity. There are also circumstances where a more broad chemical characterisation of drug samples may also be required. This involves investigating the chemical impurities that may be present in a drug sample as a consequence of their synthesis. This impurity or drug profiling can be derived from drugs which are synthesised chemically or extracted from plant materials and then modified chemically. Impurity profiling can provide some insight into the synthetic methods used and sometimes the starting chemicals used. We report on the data generated from repetitive ( n = 18 ) synthesis of ecstasy (methylenedioxymethylamphetamine or MDMA) made by three different synthetic methods. Each data sample is expressed in multiple formats. This article uses the template for publishing GCMS data provided in Miller et al.(2022)[1]. The template provides a robust and systematic approach to organise GCMS data that is both useful for practitioners and amenable for automated data manipulation by data scientists.

In vitro characterization of the pyrazole-carrying synthetic cannabinoid receptor agonist 5F-3,5-AB-PFUPPYCA and its structural analogs.

The synthetic cannabinoid receptor agonist (SCRA) market is undergoing important changes since the enactment of the 2021 class-wide generic SCRA ban in China, one of the most important source countries for new psychoactive substances (NPS). Recently, various compounds with new structural features, synthesized to bypass this legislation, have entered the recreational drug market. Certain monocyclic pyrazole-carrying "FUPPYCA" SCRAs have been sporadically detected since 2015 without gaining further popularity. However, as evidenced by their recent detection in Scottish prisons, 5F-3,5-AB-PFUPPYCA and 3,5-ADB-4en-PFUPPYCA have re-emerged, potentially triggered by the new legislative ban. The aim of this study was to characterize the in vitro intrinsic CB1 and CB2 receptor activation potential of 5F-3,5-AB-PFUPPYCA and 3,5-ADB-4en-PFUPPYCA, as well as 4 analogs (5F-3,5-ADB-PFUPPYCA, 3,5-AB-CHMFUPPYCA, 5,3-AB-CHMFUPPYCA and 5,3-ADB-4en-PFUPPYCA) using live cell ß-arrestin 2 recruitment assays. Most analogs were essentially inactive at either CB1 or CB2, with only 3,5-AB-CHMFUPPYCA, 5,3-AB-CHMFUPPYCA and 5,3-ADB-4en-PFUPPYCA showing a limited activation potential at CB1. Furthermore, the importance of the position of the tail structure was demonstrated, with 5,3 regioisomers being more active than their 3,5 analogs. Moreover, all compounds exhibited antagonistic behavior at both receptors, which may be associated with their structural resemblance to cannabinoid antagonists and inverse agonists. Although the 3,5 regioisomers of these "FUPPYCA" SCRAs circumvent the Chinese ban, it is unlikely that these SCRAs will pose a major threat to public health, given the lack of pronounced CB receptor activity.

Changing trends in novel benzodiazepine use within Scottish prisons: detection, quantitation, prevalence, and modes of use.

Drug use within prisons is increasingly complex and unpredictable. Benzodiazepines are currently one of the most common drugs detected in individuals leaving Scottish prisons; however, understanding illicit benzodiazepine use within prisons and assessing the potential harm to individuals is challenging due to the lack of available analytical data on the substances circulating. Increasingly, materials, such as paper and clothing, infused with novel benzodiazepines have been identified as a smuggling route into Scottish prisons. Methods were developed for the qualitative and quantitative analysis of benzodiazepines using gas chromatography-mass spectrometry (GC-MS) and applied to 495 seized samples from 11 Scottish prisons, including papers, cards, blotters, powders, tablets, and clothing. Evolution in the benzodiazepines being detected was demonstrated, with etizolam being the most prevalent throughout 2020/2021 following which flubromazepam and bromazolam detections increased. Additionally, significant changes in the smuggling methods and drug formats detected occurred over time following policy changes within prisons. These data represent the first reported widescale etizolam quantitation data and demonstrate high levels of variability across all sample types, most notably within tablets (0.34-2.33 mg per tablet). Additionally, concentration mapping of a whole seized card sample revealed the total concentration of drug present (312.5 mg) and demonstrated variability across the surface of the card (1.16-1.87 mg/cm2 ). These data highlight the challenges of consistent dosing for individuals and the high risks of unintentional overdose. Increased understanding of the challenge of such drug smuggling and benzodiazepine use will aid in the development of strategies to reduce supply and mitigate harm.

A comprehensive chromatographic comparison of amphetamine and methylamphetamine extracted from river water using molecular imprinted polymers and without the need for sample derivatization.

This work explores the differences between two GCMS instruments for the determination of amphetamine and methylamphetamine extracted from water samples (ultra pure water and river water) without the necessity for derivatization. The instruments contained different generations of gas chromatograph and mass selective detector components and revealed significantly different results when presented with the same samples. The extraction methodology also compared two SPE systems. The extraction efficiency of commercially available molecular imprinted polymers as a sorbent in SPE was compared with commonly used hydrophilic balance sorbent. Molecular imprinted polymers provided excellent recoveries (81 ± 2% and 108 ± 3% at 30 µg L(-1), and 94 ± 2% and 94 ± 2% at 200 µg L(-1) for amphetamine and methylamphetamine, respectively). The best LOD obtained was sufficient for the determination of both drugs extracted from river water (0.029 ± 0.003 and 0.015 ± 0.004 µg L(-1) for amphetamine and methylamphetamine, respectively). These were comparable to literature values obtained through conventional extraction and analysis using LC-MS/MS but had the advantage of being achieved using an underivatized GCMS method.

Scientometric analysis of the forensic science literature for fibre as an evidence type: Access and data availability.

The large volume of information available within citation databases has become a challenge to manage and distil in all areas of research. In this study, a scientometric approach has been applied to fibres as an evidence type using information contained in Scopus and Web of Science. A comparison was also made with the references listed in the INTERPOL International Forensic Science Managers Symposium Science (IFSMS) reports (2004-2019) where only a limited number of documents were common with the citation databases, illustrating the value of the IFSMS reports. Finally, this study also highlights that data availability and location are generally omitted in publications. The forensic science community has an opportunity to change this culture and lead the way in making their data available, aligning with the ideals of fairness, openness and transparency of the underpinning data upon which scientific developments are based.

A UK-based ground truth data set of GCMS analysed ignitable liquid samples - a template for making chromatographic data accessible as an open source data set.

Fire debris is often recovered as part of a fire scene investigation to determine whether an ignitable liquid might be present which may be evidence of a deliberate fire. The analysis of fire debris produces chromatograms that a forensic chemist uses to determine whether or not an ignitable liquid may be present. Currently there are very few publicly available data sets that can be used for training and statistical modelling in this area. The data set in this paper has been prepared with these two applications in mind and covers a wide range of ignitable liquids available in the UK. We created a data set of 35 ignitable liquids including petrol (gasoline), light, medium and heavy petroleum distillates (i.e diesel) from several retailers. Each ignitable liquid was systematically evaporated to produce six additional samples. Each sample was repetitively analysed to provide an overall data set of 751 analytical outputs (including chromatograms). Each data sample is expressed in multiple formats and the metadata containing any data used in the production of the samples is included. The folder and file names are designed to avoid misplacements and to manipulate folders and files systematically using computer code.

Chemical enhancement of footwear impressions in blood on fabric - part 1: protein stains.

A range of protein stains were utilised for the enhancement of footwear impressions on a variety of fabric types of different colours with blood as a contaminant. A semi-automated stamping device was used to deliver test impressions at a set force to minimise the variability between impressions; multiple impressions were produced and enhanced by each reagent to determine the repeatability of the enhancement. Results indicated that while most protein stains used in this study successfully enhanced impressions in blood on light coloured fabrics, background staining caused interference on natural fabrics. Enhancement on dark coloured fabrics was only achieved using fluorescent protein stains, as non-fluorescent protein stains provided poor contrast. A further comparison was performed with commercially available protein staining solutions and solutions prepared within the laboratory from the appropriate chemicals. Both solutions performed equally well, though it is recommended to use freshly prepared solutions whenever possible.

Chemical enhancement of footwear impressions in blood on fabric - part 2: peroxidase reagents.

This study investigates the optimisation of peroxidase based enhancement techniques for footwear impressions made in blood on various fabric surfaces. Four different haem reagents: leuco crystal violet (LCV), leuco malachite green (LMG), fluorescein and luminol were used to enhance the blood contaminated impressions. The enhancement techniques in this study were used successfully to enhance the impressions in blood on light coloured surfaces, however, only fluorescent and/or chemiluminescent techniques allowed visualisation on dark coloured fabrics, denim and leather. Luminol was the only technique to enhance footwear impressions made in blood on all the fabrics investigated in this study.

Novel scientific methods in court.

In recent decades the use of forensic science in investigations and therefore its subsequent presentation within the courts has increased exponentially, fuelled by an increase in scientific advances, development of databases and greater access to scientists and their expertise. This explosion in the use of forensic evidence has not been limited to one single scientific domain, as there are a broad range of scientific disciplines, encompassed by the general umbrella term' forensic science'. Many of these involve commonly applied methodologies and are accepted by the courts with limited scrutiny. Where tensions exist concerning the use of science in the courtroom is when novel or emerging sciences and scientific techniques are introduced. This may be particularly evident when the demands of the investigatory phase, where those working want to apply all possible tools at their disposal to gather as much evidence as possible and the needs of the courts, where the evidence must scientifically robust and admissible for it to be presented before a jury, come together. This paper examines the implications for the court for emerging or novel sciences and scientific techniques. In such cases, the potential rewards of implementing the scientific process and the information these may contribute to an investigation provides a temptation to investigators to push for their operational use, with the unintended consequence of posing an issue to the court when considering whether to admit the evidence into the judicial process.

Colorimetric optical nanosensors for trace explosive detection using metal nanoparticles: advances, pitfalls, and future perspective.

Warfare threats and acts of terror are challenging situations encountered by defense agencies across the globe and are of growing concern to the general public, and security-minded policy makers. Detecting ultra-low quantities of explosive compounds in remote locations or under harsh conditions for anti-terror purposes as well as the environmental monitoring of residual or discarded explosives in soil, remains a major challenge. The use of metal nanoparticles (NPs) for trace explosive detection has drawn considerable interest in recent years. For nano-based explosive sensor devices to meet real-life operational demands, analytical parameters such as, long-shelf life, stability under harsh conditions, ease-of-use, high sensitivity, excellent selectivity, and rapid signal response must be met. Generally, the analytical performance of colorimetric-based nanosensor systems is strongly dependent on the surface properties of the nanomaterial used in the colorimetric assay. The size and shape properties of metal NPs, surface functionalisation efficiency, and assay fabrication methods, are factors that influence the efficacy of colorimetric explosive nanosensor systems. This review reports on the design and analytical performances of colorimetric explosive sensor systems using metal NPs as optical signal transducers. The challenges of trace explosive detection, advances in metal NP colorimetric explosive design, limitations of each methods, and possible strategies to mitigate the problems are discussed.

Creation of a universal experimental protocol for the investigation of transfer and persistence of trace evidence: Part 1 - From design to implementation for particulate evidence.

Understanding the transfer and persistence of different types of trace evidence between different donor and receiving surfaces under specific conditions, circumstances and alleged competing defence and prosecution hypotheses is a significant need. Acquiring such a knowledge base enables hypothesis testing to be undertaken more readily and with greater confidence. A longstanding goal has been to develop a unified approach to transfer and persistence studies which are fit for purpose but also scalable. Here we propose a low cost, universal experimental protocol using a recognised and well researched proxy material for the development and aggregation of ground truth transfer and persistence data at scale. We also propose and provide the tools to enable the creation of an open source and open access data repository of experimental data to act as a resource for practitioners and researchers in addressing transfer and persistence questions.

Creation of a universal experimental protocol for the investigation of transfer and persistence of trace evidence: Part 2 - Implementation and preliminary data.

This is the second paper on the development and implementation of a universal experimental protocol for transfer and persistence of trace evidence. Here, we present the results of five individual researchers who implemented the universal experimental protocol for the first time. Over 2500 images were collected, computationally analysed and statistically compared. The results were shown to be reliable and consistent under all conditions tested and were used to model the rate of loss of transferred particles over a 7-day timescale. The protocol was additionally extended to include a test of camera settings. The protocol was found to be useable and robust in this preliminary trial paving the way for it to be deployed more widely.