Simultaneous determination of benzodiazepines in whole blood or serum by HPLC/DAD with a semi-micro column

A simple and sensitive high performance liquid chromatographic (HPLC) metho d using a semi-micro column, C-8 reversed-phase column (3 mm i.d.) and a lo w flow rate 0.3 ml/min was developed and validated for the determination of five frequently prescribed benzodiazepines: clonazepam, diazepam. flunitra zepam, midazolam and oxazepam. Quantification was performed at 220 nm with methylclonazepam as internal standard. The method involved a simple extract ion fi om alkalinized blood (1 mi) into 1-chlorobutane and provided excelle nt sensitivity, recovery, accuracy and reproducibility for benzodiazepines in therapeutic or toxic concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.