HPLC with ultraviolet detection for the determination of chloroquine and desethylchloroquine in whole blood and finger-prick capillary blood dried on filter paper

A simple, sensitive, selective and reproducible method based on liquid chromatography was developed for the determination of chloroquine (CQ) and its active plasma metabolite desethylchloroquine (DECQ) in finger-pricked capillary blood spot onto filter paper (DBS) and whole blood samples. Both were separated from the internal standard quinine on a reversed phase C18 column, with the mobile phase consisting of a mixture of 1% diethylamine, acetonitrile and methanol (20:55:25, v:v:v) running at a flow rate of 1.0 ml/min. Retention times of QN, DECQ and CQ were 4.5, 5.7 and 6.4 min, respectively. Ultraviolet detection was at the wavelength 256 nm. Sample preparation was done by extraction with hexane and tert-butyl methyl ether (1:1, v:v). Good precision and accuracy were obtained for both within-day repeatability and day-to-day reproducibility. Limit of quantification (LOQ) for both CQ and DECQ was accepted as 50 ng/ml using 80 μl DBS sample and 25 ng/ml using 150 μl whole blood sample. The mean recoveries for CQ, DECQ and internal standard for both whole blood and DBS were between 74 and 87%. The method was successfully applied for a pharmacokinetic study of CQ and DECQ in patients with Plasmodium vivax. Excellence correlation (r = 0.997) was observed between the analysis of both CQ and DECQ in paired whole blood and DBS samples.