An Early Warning Monitoring System for Illicit Drug Use at Large Public Events: ‘Close to Real Time’ Trace Residue Analysis of Discarded Drug Packaging Samples

Inspired by the exchange principle espoused by Edmond Locard (1877-1966), which states “every contact leaves a trace”, we report here the development and application of a strategy for trace residue sampling and analysis of discarded ‘Drug Packaging Samples’ (DPS), as part of an early warning monitoring system for illicit drug use at large public events. Using Direct Analysis in Real Time (DART) - mass spectrometry (MS) and -tandem mass<br>spectrometry (MS/MS), rapid and high-throughput identification and characterisation of a wide range of illicit drugs and adulterant substances was achieved, including those present in complex poly-drug mixtures and at low relative abundances, and with analysis times of less than one minute per sample. 1362 DPS were analysed either ‘off-site’ using laboratory-based instrumentation or in ‘on-site’ in ‘close to real time’ using a transportable mass spectrometer housed within a customised mobile analytical laboratory. 92.2% of DPS yielded positive results for at least one of 15 different pharmacologically active drugs and/or adulterants, including cocaine, MDMA, and ketamine, as well as numerous ‘novel psychoactive substances’ (NPS). Notably, polydrug mixtures were more common than single drugs, with 52.6% of positive DPS found to contain more than one substance, and with 42 different drug and polydrug combinations observed throughout the study. For analyses performed ‘on-site’, reports to key stakeholders including event organisers, first aid and medical personnel, and peer-based harm reduction workers could be provided in as little as 5 minutes after sample collection. Then, following risk assessment of the potential harms associated with their use, drug advisories or alerts were then disseminated to event staff and patrons, and subsequently to the general public, when substances with particularly toxic properties were identified.<br>