Rapid enzyme-linked immunosorbent assay (ELISA) with a visual end-point for detecting quinine in urine, serum and dried blood spots

Abstract

A rapid and simple assay has been developed for the detection of quinine in biological fluids (e.g., urine, serum and dried blood spots). The assay has a coloured end-point and a limit of sensitivity of 3 µg l^–1, using 5-µl samples. No cross-reactivity is observed with examples of commonly administered drugs. The assay was used to screen samples of dried blood spots and urine from a volunteer after taking a dose of 300 mg of quinine. The assay requires no sophisticated laboratory equipment or instrumentation to give a qualitative assessment of the presence of quinine, but may be used with a simple portable microtitre plate reader to give quantitative measurements if required.