A comprehensive analytical process, from NPS threat identification to systematic screening: Method validation and one-year prevalence study.

Several New Psychoactive Substances (NPS) enter the illicit drug market each year. This constant evolution of compounds to screen is challenging to law enforcement and drug chemists, and even more so to forensic toxicologists, who need to detect such compounds which might be at low concentrations in complex biological matrices. While some technological solutions are better suited than others to address such a challenge (e.g., high resolution mass spectrometry), laboratories with limited instrumental and financial resources are faced with a complex task: systematically screening for a rapidly evolving NPS panel using an accredited method run on standard equipment (e.g., liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)). This work presents a solution to this challenge: a complete workflow from the detection of a regional NPS threat to its implementation in a method accredited under the ISO 17025:2017 norm. Initial LC-MS/MS method included 55 NPS and metabolites (31 Novel Synthetic Opioids (NSO), 22 NSO metabolites and 2 designer benzodiazepines). Following their identification as relevant territorial threats, flualprazolam, then isotonitazene, were added to the contingent. By relying on development aiming for maximal integration to the current analysis workflow, systematic NPS screening using this method was easily implemented. Between March 2019 and March 2020, the 5 079 forensic cases analyzed in the province of Québec (Canada) revealed a NPS positivity rate of 3.4%. While 94% involved designer benzodiazepines, 5% involved NSO. This process, combining high efficiency, simple detection technology, ISO accreditation and rapid response to new threats resulted in a four-fold increase in NPS detection.