Application of microwave irradiation to fast and efficient isolation of benzodiazepines from human hair

The aim of this research was to develop, optimize and validate a modern and rapid method of preparation of human hair samples using microwave irradiation for the purpose of determination of six benzodiazepines: alprazolam, estazolam, lorazepam, clonazepam, diazepam and tetrazepam, with lormetazepam as an internal standard (IS). Extracts were analyzed ultrahigh performance liquid chromatography with mass spectrometry time of flight detection (UHPLC–MS–TOF). Optimal parameters of microwave-assisted extraction (type of extraction solvent, extraction temperature, extraction time and pH of borate buffer) for these drugs in spiked hair samples were defined. The limit of detection ((0.003–0.025 ng/mg), intra- (1.5–4.3%) and interday (2.3–8.3%) precision (CV) and accuracy of the assay (89.8–105.7%) at three concentration levels: 0.22, 2.22 and 5.56 ng/mg were calculated. The optimized and validated MAE/UHPLC–MS–TOF method was then applied for analysis of clinical hair sample.