Fast and Sensitive Method for the Determination of 17 Designer Benzodiazepines in Hair by Liquid Chromatography–Tandem Mass Spectrometry

In recent years, identification and analysis of designer benzodiazepines have become a challenge in forensic toxicology. These substances are analogs of the classic benzodiazepines, but their pharmacology is not well known, and many of them have been associated with overdoses and deaths. As a result, there has been a surge in efforts to develop analytical methods to determine these compounds in different biological samples. Our aim was to develop and validate a fast, sensitive and specific method for determining 17 designer benzodiazepines (adinazolam, clobazam, clonazolam, delorazepam, deschloroetizolam, diclazepam, etizolam, flualprazolam, flubromazepam, flubromazolam, flunitrazolam, N-desmethylclobazam, nifoxipam, nitrazolam, meclonazepam, pyrazolam and zolazepam) in hair by liquid chromatography–tandem mass spectrometry (LC–MS-MS). Hair samples were decontaminated and pulverized, and a 20 mg aliquot was incubated in methanol in an ultrasound bath (1 h, 25°C). The supernatant was evaporated and reconstituted in 200 µL of mobile phase, and the extracts were filtered (nano-filter vials) before injection into LC–MS-MS. All analytes were eluted from the chromatographic column in 8 min, and two multiple-reaction monitoring (MRM) transitions were used to identify each compound. The limits of quantification were 5 or 25 pg/mg depending on the analyte, and the calibration functions were linear to 200 pg/mg. Imprecision was 70% and displayed ion suppression between −62.8% and −23.9% (n = 10). The method was applied to 19 authentic cases. Five samples were positive for flualprazolam ( 200 pg/mg) and/or etizolam (47.4–88.5 pg/mg). In conclusion, the present validated method has proven to be fast, sensitive, specific and capable of determining 17 designer benzodiazepines in hair using LC–MS-MS.