Confirmation of benzodiazepines in urine as trimethylsilyl derivatives using gas chromatography-mass spectrometry

A confirmation procedure for the identification and quantitation of various benzodiazepines in urine is presented. The urine sample is first hydrolyzed enzymatically because of the glucuronide conjugation of some benzodiazepine metabolites, then extracted using bonded-phase columns. After elution into an organic solvent, the samples are evaporated, converted to the trimethylsilyl ether derivatives and analyzed by electron ionization GC-MS. Quantitation was performed using selected-ion monitoring for each benzodiazepine using prazepam as the internal standard. The method provides excellent linearity and sensitivity for the trimethylsilyl derivatives.