Optimised determination of clobazam in human plasma with extraction and high-performance liquid chromatography analysis

The analysis of clobazam by high-performance liquid chromatography and UV detection is described herein. After adding an internal standard, 600 μl of plasma were extracted under basic conditions onto disposable cartridges packed with celite. The organic extract was then evaporated to dryness and the residue reconstituted in 200 μl of mobile phase. A 20 μl aliquot was injected into chromatograph. The HPLC system was equipped with an Ultrasphere C8 analytical column coupled with an UV detector set at 235 nm. The mobile phase was an acetate buffer 20 mM, pH 5.5, containing acetonitrile and triethylamine 70:30:0.01 (v/v); the flow-rate was 1.8 ml/min. Using this method, clobazam can be detected with a sensitivity limit of 6 ng/ml and the RSD% intra- and inter-assay were lower than 5%. For its ruggedness and reliability, the proposed method is particularly suitable for therapeutic drug monitoring in epilepsy.