Profiling of cocaine using ratios of GC-MS peaks

Shape matters: The application of activity-based in vitro bioassays and chiral profiling to the pharmacological evaluation of synthetic cannabinoid receptor agonists in drug-infused papers seized in prisons

Synthetic cannabinoid receptor agonists (SCRAs) elicit many of their psychoactive effects via type-1 human cannabinoid (CB₁ ) receptors. Enantiomer pairs of eight tert-leucinate or valinate indole- and indazole-3-carboxamide SCRAs were synthesized and their CB₁ potency and efficacy assessed using an in vitro β-arrestin recruitment assay in a HEK239T stable cell system. A chiral high-performance liquid chromatography method with photodiode array and/or quadrupole time-of-flight-mass spectrometry detection (HPLC-PDA and HPLC-PDA-QToF-MS) was applied to 177 SCRA-infused paper samples seized in Scottish prisons between 2018 and 2020. In most samples, SCRAs were almost enantiopure (S)-enantiomer (>98% of total chromatographic peak area), although in some (n = 18), 2% to 16% of the (R)-enantiomer was detected. (S)-enantiomers are consistently more potent than (R)-enantiomers and often more efficacious. The importance of SCRA-CB₁ receptor interactions in the "head" or "linked group" moiety is demonstrated, with the conformation of the "bulky" tert-leucinate group greatly affecting potency (by up to a factor of 374), significantly greater than the difference observed between valinate SCRA enantiomers. (S)-MDMB-4en-PINACA, (S)-4F-MDMB-BINACA, and (S)-5F-MDMB-PICA are currently the most prevalent SCRAs in Scottish prisons, and all have similar high potency (EC₅₀ , 1-5 nM) and efficacy. Infused paper samples were compared using estimated intrinsic efficacy at the CB₁ receptor (EIE_CB1 ) to evaluate samples with variable SCRA content. Given their similar potency and efficacy, any variation in CB₁ receptor-mediated psychoactive effects are likely to derive from variation in dose, mode of use, pharmacokinetic differences, and individual factors affecting the user, rather than differences in the specific SCRA present.

Chemometrics in forensic chemistry - Part I: Implications to the forensic workflow

The forensic literature shows a clear trend towards increasing use of chemometrics (i.e. multivariate analysis and other statistical methods). This can be seen in different disciplines such as drug profiling, arson debris analysis, spectral imaging, glass analysis, age determination, and more. In particular, current chemometric applications cover low-dimensional (e.g. drug impurity profiles) and high-dimensional data (e.g. Infrared and Raman spectra) and are therefore useful in many forensic disciplines. There is a dominant and increasing need in forensic chemistry for reliable and structured processing and interpretation of analytical data. This is especially true when classification (grouping) or profiling (batch comparison) is of interest. Chemometrics can provide additional information in complex crime cases and enhance productivity by improving the processes of data handling and interpretation in various applications. However, the use of chemometrics in everyday work tasks is often considered demanding by forensic scientists and, consequently, they are only reluctantly used. This article and following planned contributions are dedicated to those forensic chemists, interested in applying chemometrics but for any reasons are limited in the proper application of statistical tools - usually made for professionals - or the direct support of statisticians. Without claiming to be comprehensive, the literature reviewed revealed a sufficient overview towards the preferably used data handling and chemometric methods used to answer the forensic question. With this basis, a software tool will be designed (part of the EU project STEFA-G02) and handed out to forensic chemist with all necessary elements of data handling and evaluation. Because practical casework is less and less accompanied from the beginning to the end out of the same hand, more and more interfaces are built in through specialization of individuals. This article presents key influencing elements in the forensic workflow related to the most meaningful chemometric application and evaluation.

Stability of amphetamine impurity profiles during 12 months of storage

Impurity profiling is a well described forensic tool that may be applied to gain information about the illegal drug market. However, it requires experience to assess the correlation between chemical profiles thereby separating linked from unlinked samples. One of the challenges in this context is that the chemical profiles may change over time, thus complicating an assessment if samples are stored under different conditions. In this study, the impact of different storage conditions on the stability of amphetamine impurity profiles was investigated. We examined the influence of storage time, temperature, sample purity, sample quantity and the presence of methanol on the amphetamine profile stability when stored for up to 12 months. We find that the target compounds in amphetamine impurity profiles are susceptible to all the examined storage conditions. Consequently, this unstable nature of amphetamine profiles may complicate the assessment when comparing amphetamine seizures that has been separated for longer time periods or stored under different conditions prior to seizure. Knowledge about the seizure history is rarely available to the forensic analyst. Therefore, sample stability issues should be taken into account when comparisons of chemical profiles are made.