A procedure for the determination of 5-fluorouracil in tissue using microbore HPLC and fluorescence detection

For the determination of the cytotoxic drug 5-fluorouracil in tissue, a sensitive and selective assay has been developed based on microbore high-performance liquid chromatography and fluorescence detection after pre-column derivatization with 4-bromomethyl-7-methoxycoumarin. 5-Chlorouracil was found to be an appropriate internal standard. A column switching protocol has been devised to separate the analyte from late eluting matrix components and the natural uracil. The drug can be determined at concentrations in the low ng/g wet tissue range with a detection limit of 3 ng/g; furthermore, the same protocol can be applied to analyze serum and plasma samples. The procedure was employed to determine the drug in samples taken from human liver tumors and metastases after an intra-arterial bolus administration and from epithelial carcinomas after systemic continuous application.