Enantioselective assay of chloroquine and its main metabolite deethyl chloroquine in human plasma by capillary electrophoresis

A sensitive assay for the determination of chloroquine (Clq) and its pharmacologically active metabolite deethyl chloroquine in plasma by capillary electrophoresis (CE) is developed. Plasma levels of drug and metabolite are measured using HeCd laser-induced fluorescence (LIF) detection over a range of three orders of magnitude from 2 to 1000 ng/mL after liquid-liquid extraction. A limit of detection of 0.5 ng/mL is achieved. Validation of the method yields intra- and interday precision data within the limits of 10% (20% at limit of quantitation) and intra- and interday accuracy data greater than 6% throughout the whole working range. The method is applied for the drug monitoring of patients treated with Clq. Based upon this assay, two enantioselective CE-LIF methods for Clq and its main metabolite are developed. Mixtures of substituted gamma-cyclodextrins are used as chiral selectors. A baseline separation of the enantiomers of both analytes in one run is achieved in less than 11 min (method A) and less than 9 min (method B), respectively. Hydroxychloroquine is used as the internal standard for both methods.