Determination of clevidipine and its primary metabolite in rat plasma by a dispersive liquid-liquid microextraction method.

Dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet combined with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) was developed for the determination of clevidipine and its primary metabolite in Sprague-Dawley rat plasma samples. During the extraction procedure, to facilitate an efficient procedure, the plasma protein was precipitated first by using a mixture of a zinc sulfate solution and acetonitrile. Several extraction parameters were carefully evaluated and optimized, including the type and volume of the extraction solvent, salt effect, pH and extraction time. Under the optimum conditions, the limits for quantification were 2.5 and 5.0 ng mL(-1) for clevidipine and its primary metabolite, respectively. Sufficient linearity of clevidipine or its primary metabolite was observed with the coefficient of correlation (r) above 0.9979. The method showed good precision and accuracy, with intra- and inter-assay coefficients of variation <6.1% at all concentrations. The proposed pretreatment technique with HPLC was successfully applied to the determinate of clevidipine and its primary metabolite in rat plasma samples. Furthermore, the method, which requires less time than conventional techniques, is environmentally friendly and requires only a small amount of low-toxicity extraction solvent.