Quantification of clotiazepam in human plasma by gas chromatography–mass spectrometry

An analytical procedure was developed and validated for the quantification of clotiazepam in human plasma. After subjecting plasma samples to solid-phase extraction, the extract was evaporated and the residue re-constituted. An aliquot of the mixture was injected onto a gas chromatography–mass spectrometry system. The detector response was linear for clotiazepam concentrations in the range of 5–200 ng/ml. Intra- and inter-day precision for the assay over the concentration range was below 13.1 and 13.5%, and the accuracy ranged between 99.0–107.9% and 92.4–101.3%, respectively. The drug was found to be stable under various processing conditions used. The method is applicable to human pharmacokinetic studies of clotiazepam.