Determination of diltiazem in human whole blood and plasma by high-performance liquid chromatography using a polymeric reversed-phase column and utilizing a salting-out extraction procedure

Abstract

A rapid, simple and sensitive reversed-phase high-performance liquid chromatography method for the separation and measurement of the concentration of diltiazem in human whole blood and plasma has been developed. The method involves a simple one-step solvent extraction of the drug from biological samples followed by salting-out the organic solvent using ammonium sulfate. A 15 cm × 4.1 mm, PRP-1, pH-stable (pH 1–13) polymeric reversed-phase column was used with an isocratic elution of acetonitrile—0.01 M tetrabutylammonium hydroxide (60:40, v/v). Diltiazem was monitored at 254 nm and 0.50–0.005 a.u.f.s. The completion time for assay was less than 15 min, and the limit of detection was 10 ng/ml at a signal-to-noise ratio of 3 for a 50-μl injection volume. Using this method, the pharmacokinetic parameters (elimination rate constant, elimination half-life and area under the curve) were calculated from a whole blood concentration versus time profile of diltiazem.