Simultaneous determination of risperidone and 9-hydroxyrisperidone enantiomers in human blood plasma by liquid chromatography with electrochemical detection.

Risperidone is a commonly prescribed antipsychotic drug. An enantioselective HPLC method with electrochemical detection was developed and validated for simultaneous determination of plasma concentrations of risperidone and its active metabolites, 9-hydroxyrisperidone enantiomers. Following solid phase extraction of 1.0 mL blood plasma, a baseline separation of the analytes was achieved on an AGP (alpha1 acid glycoprotein) column using isocratic mobile phase consisting of methanol-phosphate buffer (pH 6.2; 0.1 M) (15:85, v/v). Total analysis run time was 11 min. For the detection of the analytes analytical cell potentials were set at 500, 650, 950, and 950 mV. The method linearity was attained in the range from 1.0 to 100 ng/mL for risperidone and both 9-hydroxyrisperidone enantiomers. The limit of detection was 0.5 ng/mL for all three analytes. The method was precise and accurate and was successfully applied in a clinical study investigating the stereoselectivity of risperidone 9-hydroxylation.