Determination of 5-fluorouracil in human plasma by high-pressure ion-exchange chromatography

A method has been developed for the measurement of 5-fluorouracil by isocratic high-pressure ion-exchange liquid chromatography. Chlorpheniramine was added to the standards and samples before extraction with 16% isopropanol in ethyl acetate. The extracts were then chromatographed using a mobile phase of 0.014 mol/l ammonium dihydrogen phosphate buffer, pH 3.5, at a flow rate of 1 ml/min. Ultraviolet detection at 266 nm was used, and quantitation was by measurement of the peak height ratios of 5-fluorouracil to chlorpheniramine.