Subnanogram quantitation of chlorpromazine in plasma by high-performance liquid chromatography with electrochemical detection.

A specific and sensitive high-performance liquid chromatographic (HPLC) method for the quantitative determination of subnanogram levels of chlorpromazine in plasma is described. Following extraction of chlorpromazine and the internal standard, prochlorperazine, HPLC analysis is carried out on a cyano column with a mobile phase consisting of 0.1 M ammonium acetate in acetonitrile (10:90 v/v). The use of oxidative thin-layer amperometric detection allowed the quantitation of 0.25 ng of chlorpromazine/ml of plasma with a coefficient of variation of 5.1%. The HPLC method has adequate sensitivity to follow plasma concentration-time profiles up to 24 hr following low single oral doses of chlorpromazine in healthy volunteers.