“…Various methods for the determination of benzodiazepines in biological materials have been reported. Analytical methods for underivatized oxazolobenzodiazepines and other benzodiazepines include thin-layer chromatography (TLC) [2,3], high-performance (HP) TLC [4], gas chromatography (GC) [3,[5][6][7], GC-mass spectrometry (MS) [3,5,[7][8][9], high-performance liquid chromatography (HPLC) [3,10,11], and immunoassays [12]. However, simultaneous determination of methylated oxazolobenzodiazepine drugs by GC or GC/MS has not been reported to our knowledge.…”