Determination of 1,4-benzodiazepines by high-performance liquid chromatography-electrospray tandem mass spectrometry

A sensitive and selective method to determine diazepam, N-desmethyldiazepam, nitrazepam, flunitrazepam and medazepam in human serum and urine was established employing solid-phase extraction and high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) with the selected reaction monitoring (SRM) mode. Using diazepam-d5 and N-desmethyldiazepam-d5 as internal standards, recoveries between 90.4 and 109.7% were determined. The routine quantification limit was set at 2 ng/ml for serum and urine at a signal-to-noise ratio of 10:1.