A method for rapid determination of lorazepam by high-performance liquid chromatography.

A new sensitive method using solid-phase column extraction and high-performance liquid chromatography (HPLC) has been developed for the determination of lorazepam and its glucuronide metabolite in human plasma. Extraction was performed with a C2-Bond Elut column followed by reverse-phase HPLC of the sample. The detection limit of lorazepam in plasma was 0.5 micrograms/L. Standard curves over the concentration range from 2.5 to 75 micrograms/L had good linearity. Intra-assay variability ranged from 2.0 to 6.2% and interassay variability from 4.8 to 8% at the concentration range of 5-50 micrograms/L.