Simple and cost-effective liquid chromatographic method for determination of pyrimethamine in whole blood samples dried on filter paper

Abstract: A cost-effective HPLC method for determination of pyrimethamine (PYR) in human whole blood samples dried on filter paper (Whatman®) is reported. Trimethoprim (TMP) was used as an internal standard. Whole blood spiked with PYR was transferred (100μl) onto filter paper and dried at room temperature. Capillary blood samples (100μl) after ingestion of three tablets of sulfadoxine-pyrimethamine (SP) by one subject were also tested. PYR and an internal standard (IS) TMP were extracted into di-isopropyl ether as bases and then re-extracted with 150μl mobile phase. A C-18 column was used and the mobile phase consisted of phosphate buffer (0.05M, pH 5):acetonitrile:concentrated perchloric acid (750:300:2.5, v/v/v). The absorbances of PYR and IS were monitored at 270nm. The limit of quantification was 40ng/ml. The within- and between-assay coefficient of variations were <10% at the limit of quantification. [Copyright &y& Elsevier]