High-performance liquid chromatographic method for the determination of quinine and 3-hydroxyquinine in blood samples dried on filter paper

A simple high-performance liquid chromatographic method for the simultaneous analysis of quinine and 3-hydroxyquinine in blood samples dried on filter paper is described. Sample preparation involves liquid-liquid extraction with toluene-butanol 75:25 (v/v) followed by evaporation. A reversed-phase liquid chromatography system with fluorescence detection was used. The limit of determination was 10 nM for both quinine and 3-hydroxyquinine and the recovery varied between 78 and 109%. The within- and between-assay coefficients of variation varied between 2-5% and 4-10%, respectively. No loss of either analyte occurred after storage for 2 months at room temperature or at 37degreesC. This method for sampling has advantages that make it of great value for clinical and pharmacokinetic studies especially in remote regions where storage and transportation is problematic. (C) 2003 Elsevier B.V. All rights reserved.