Are the NPS commonly used? An extensive investigation in Northern Italy based on hair analysis

New Psychoactive Substances (NPS) are present on the Italian illicit markets but data from the analysis of biological samples to evaluate their real consumption are rare. For this reason, an epidemiological study was carried out by means a UPLC-MS/MS method for the determination of 115 NPS on keratin matrix. A total of 847 hair samples was collected in 2020 and 2021 and analysed. The sample donors were in the age range 18-40 years, from both genders, and were tested either for driving re-licensing or for drug withdrawal monitoring. The UPLC-MS/MS system consisted of a Waters ACQUITY UPLC® I-Class, coupled with a Waters XEVO TQ-XS triple quadrupole mass spectrometer. The method was developed and fully validated according to international guidelines. LODs were set as the minimum criterion to identify positive samples. Overall, 56 samples resulted positive for ketamine, 35 for norketamine, 6 for fentanyl, 3 for norfentanyl, 3 for 4-ANPP, 3 for MDMB-4en-PINACA, 2 for N,N-DMT, 2 for 5-chloro AB-PINACA, 1 for α-PHP and 1 for methcathinone. NPS were detected in a small part of samples (8.4%), which seems in contrast with their apparent wide diffusion in Italy, yet it is congruent with similar investigation based on hair analysis. Future studies will be performed to expand the investigated population, especially in terms of age and origin.