A New Multi-Analyte LC-MS-MS Screening Method for the Detection of 120 NPSs and 49 Drugs in Hair

Abstract

Liquid chromatography coupled with mass spectrometry (LC-MS) has been increasingly used for screening purposes in forensic toxicology. High versatility and low time/resource consumption are the main advantages of this technology. Numerous multi-analyte methods have been validated in order to face the analytical challenge of new psychoactive substances (NPSs). However, forensic toxicologists must focus the attention also on "classical" NPSs and medicines, such as benzodiazepines (BDZs) and prescription opioids. In this paper, a new method for the simultaneous detection of 169 substances (120 NPSs and 49 other drugs) in hair by LC-MS-MS is described. After the decontamination of hair samples with dichloromethane, a 20-mg aliquot of the sample was mixed with 1 mL of methanol (MeOH; 0.1% of formic acid) and then sonicated at room temperature for 2 h. The mixture was then dried under nitrogen stream and reconstituted with 100 µL of MeOH. LC separation was achieved with a 100-mm-long C18 column in 35 min, and mass acquisition was performed in dynamic multiple reaction monitoring mode and in positive ionization. The analysis results were very sensitive, with the limit of quantification ranging from 0.07 to 10.0 pg/mg. Accuracy and precision were always within the acceptable criteria. Matrix effect and recovery rate ranges were from -21.3 to + 21.9% and from 75.0 to 99.3%, respectively. The new method was successfully applied in a preliminary study on the prevalence of NPSs, BDZs and other substances in case of driving license issuance. In 14% of cases, BDZs/antidepressants (mainly trazodone, diazepam/nordiazepam and flunitrazepam) were found. Codeine, ketamine, methylone and mephedrone were also detected.