The analysis and detection of synthetic cathinones in hair - state of the art, challenges, and future aspects

Psychoactive and new psychoactive substance (NPS) analysis in hair has gained significant attention in clinical and forensic toxicology for assessing past and ongoing drug exposure. Synthetic cathinones (SCt), a prominent class of NPS, are widely abused globally and pose significant health risks due to their toxicity. The constant synthesis and marketing of new SCt compounds make their detection a growing challenge. This review summarises and evaluates analytical methods used for detecting SCt in human hair. It addresses (i) the background, prevalence, patterns of use, chemistry, pharmacokinetics, pharmacodynamics, and toxicological effects of SCt on humans and (ii) highlights methods applied in post-mortem analysis, drug-facilitated sexual assault, and workplace drug testing. A thorough search of PubMed and Google Scholar identified studies published since 2012, focusing on analytical methods for SCt detection. Most studies employed liquid chromatography coupled to (tandem) mass spectrometry, with attention to preanalytical steps such as decontamination, analyte extraction, and sample clean-up. SCt concentrations in hair were reported from the low pg/mg to ng/mg range. However, challenges persist, including external contamination, the absence of cut-off values for distinguishing occasional from chronic use, and interpretative difficulties. Advances in analytical techniques are critical to address the dynamic NPS market and ensure new compounds are detected. Sensitive methods and robust extraction procedures are essential for accurate detection, enabling forensic toxicologists to determine patterns of abuse and assess SCt’s role in forensic investigations.