Determination of chlorthalidone in human plasma by reversed-phase micellar liquid chromatography
A micellar liquid chromatographic method for the determination of the diuretic chlorthalidone in human plasma is described. It involves the extraction of the drug and the internal standard xipamide into diethyl ether-isopropanol (19 + 1). Following evaporation of the organic phase, the reconstituted residues are analysed on a C8 reversed-phase column with a mobile phase of 0.05 M sodium dodecyl sulphate-propanol (95 + 5). The drug and internal standard are detected by ultraviolet absorption at 235 nm. The method is precise with mean coefficients of variation of 4.6 and 3.1% for within-batch (intra-assay) and between-batch (inter-assay) runs, respectively. The recovery is greater than 70% and the method has a limit of detection of 50 ng ml–1 of chlorthalidone in plasma.