Validated method for the therapeutic drug monitoring of flunitrazepam in human serum using liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry with an ion trap detector

An HPLC-MS-MS method for the quantitative analysis of flunitrazepam in human serum was established. The method features a very simple liquid-liquid extraction, the use of a standard 4-mm HPLC column, isocratic elution using a buffer-free solvent, short retention times in connection with good peak resolution and the sensitivity and selectivity of an ion trap MS-MS detector. The procedure enables unambiguous identification of analytes by their product ion spectra, as well as sensitive quantitation (limit of quantitation for flunitrazepam=0.5 ng/ml). This feature was used for the confirmation of HPLC-UV results for nitrazepam. (C) 2000 Elsevier Science B.V. All rights reserved.