Simão, A YTokuyama, P YZampieri, GRocha, VMadruga, CIsicawa, KCidade, L SAlmeida, K Rda Silva, N RBarroso, MárioAndraus, MGallardo, E2026-01-292026-01-292025-06Simão, A. Y., Tokuyama, P. Y., Zampieri, G., Rocha, V., Madruga, C., Isicawa, K., Cidade, L. S., Almeida, K. R., da Silva, N. R., Barroso, M., Andraus, M., & Gallardo, E. (2025). Analysis of drugs of abuse and contaminants in individuals under drug surveillance programs: A study in hair samples. Forensic science international, 371, 112493.1872-6283http://hdl.handle.net/10400.26/61310In this study, over 900 hair samples from individuals using drugs of abuse in São Paulo and Rio Grande do Sul, Brazil were analysed for classical drugs and new psychoactive substances (NPS) in hair samples. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed for the detection of some drugs (25B-NBOMe, 25C-NBOMe, 25E-NBOH, 2C-C, 2C-I, 3,4-MDPHP, 3-MeO-PCP, 5F-MDMB-PINACA, 5-MeO-DMT, cannabidiol, ethylone, JWH 073, ketamine, mephedrone and UR-144) and drug adulterants (levamisole, phenacetin, strychnine); other substances including cocaine, amphetamines, benzodiazepines, opioids, cannabinoids were also analysed. The methods demonstrated good selectivity, linearity with lower limits of quantification ranging from 0.02 to 0.26 ng/mg, as well as precision and accuracy meeting ISO/IEC 17025 criteria. A total of 29.8 % samples were positive for at least one drug. Cocaine and its metabolites were the most frequently detected, with benzoylecgonine (111 cases), cocaine (88 cases), and cocaethylene (37 cases), highlighting prevalent cocaine use. Cannabinoids were also common, with THC (57 cases) and CBN (48 cases) detected. The presence of adulterants such as phenacetin (76 cases), levamisole (14 cases), and strychnine (3 cases) were also identified. Additionally, 5F-MDMB-PINACA was also detected (5 cases), along with ketamine (9 cases). Findings also highlighted a prevalence of poly-drug consumption, where THC was frequently detected with cocaine (20 cases) and benzoylecgonine (26 cases). CBN also showed notable associations with cocaine (16 cases) and benzoylecgonine (22 cases). These findings provide important insights into the evolving drug landscape in Brazil and highlight the effectiveness of hair analysis as a tool for monitoring drug use.enCocaine contaminantsDrugs of abuseHair analysisLC-MS/MSPsychoactive substancesjournal article10.1016/j.forsciint.2025.112493