Determination of quinine in serum, plasma, red blood cells and whole blood in healthy and Plasmodium falciparum malaria cases by high-performance liquid chromatography.

A normal-phase high-performance liquid chromatographic method using dichloromethane-methanol-1 M perchloric acid (100:9:0.4, v/v) at a flow-rate of 0.8 ml/min on a Zorbax-Sil column with fluorescence detection has been developed for the separation of quinine and quinidine from other antimalarials. Within-day and day-to-day coefficients of variation averaged 0.74 and 7.56%, respectively. The extraction recovery of quinine for plasma, serum, red blood cells and whole blood (filter paper) was 88.13, 87.12, 78.0 and 77.5%, respectively. The method is capable of separating quinine from dihydroquinine, a compound usually found as an impurity in authentic quinine samples. The method has been used for the determination of quinine in plasma, serum, red blood cells and whole blood (filter paper) of six healthy and twenty Plasmodium falciparum malaria cases. The average quinine concentration in P. falciparum malaria cases was three to four times higher than that in healthy volunteers. Quinine was absorbed much less in red blood cells than in plasma or serum.