Determination of methadone and eight new psychoactive substances in hair samples by gas chromatography/mass spectrometry

Many new psychoactive substances (NPSs) with different chemical structures have emerged in the illicit drug market in the last decade. The present work was aimed at the development of a simple method in gas chromatography/mass spectrometry (MS) for the determination of NPS of different classes, the use of cannabinoids, and, at the same time, the evaluation of methadone therapy in hair matrix, within our routine analysis control for methadone treatment or from autopsy cases. The determination of synthetic cannabinoids and methadone therapy used an extraction method based on incubation in concentrated sodium hydroxide (NaOH) solution, providing a dissolution of the keratin matrix. The described method was applied on 15 authentic specimens from our cases: five showed the presence of methadone and 2‑ethylidene‑1,5‑dimethyl‑3,3‑diphenylpyrrolidine (EDDP). The described method can be useful not only in the forensic investigation of NPS‑related addiction histories but also in epidemiological and retrospective studies on the spread of NPS among specific safety‑sensitive social workers. The GC instrument was an Agilent 7820A (Agilent Technologies, Santa Clara, CA, USA), and the detection system was an Agilent 5977B single quadrupole MS operating in selective ion monitoring mode. Validation parameters such as limit of detections (LODs), limit of quantifications (LOQs), repeatability, accuracy, and linearity were satisfactory for its application on real specimens. LODs, LOQs, R2, %CV, standard deviation, and the mean concentration for the analyzed compounds are reported in Table 1b. Accuracy and repeatability were acceptable for all the analytes at their respective LOQs. Recovery experiments varied from 58.3% to 103.0%, thus allowing the application on authentic specimens. The described method can be useful not only in the forensic investigation of NPS‑related addiction histories but also in epidemiological and retrospective studies on the spread of NPS among specific safety‑sensitive social workers, such as drivers.