Simultaneous quantitation of chlormethiazole and two of its metabolites in blood and plasma by gas--liquid chromatography.

A simple and rapid gas chromatographic method for the quantitation of chlormethiazole and two of its pharmacologically active metabolites, 5-acetyl-4-methylthiazole and 5-(1-hydroxyethyl)-4-methylthiazole, in plasma and blood is described. The total analysis time is less than 20 min for a single sample. The method requires 50--500 microliter of plasma or 1 ml of blood. The compounds are detected with a nitrogen--phosphorus detector. An internal standard technique is used for the quantitation. Calibration data are linear over the range 32--2376 ng of chlormethiazole and a similar range of the metabolites in plasma. The method may be used for pharmacokinetic studies.