Automated determination of 5-fluorouracil and its metabolite in urine by high-performance liquid chromatography with column switching

We report a quantitative assay of 5-fluorouracil (FU) and its metabolite, 5 -fluorodihydrouracil (FDHU) in human urine by used a column-switching high- performance liquid chromatographic method. The analyses were carried out us ing a molecular exclusion column for sample purification, and a cation -exc hange column for separation. Each sample required only 40 min to analyze, a nd required no preparation other than filtration. Linearity was verified up to 1000 nmol/ml (r>0.993). The recovery of FU was 96-101%; recovery of FDH U was 96-105%. The imprecision (RSD) for FU (10-100 nmol/ml) was <1.5%, sam e-day (n=5), and <1.8%, day-to-day (n=5). The imprecision (RSD) for FDHU (1 0-100 nmol/ml) was <3.2%, same-day (n=5), and <4.0%, day-to-day (n=5). The detection limits were, respectively, 0.1 nmol/ml. We measured FU and FDHU i n urine of seven cancer patients after oral administration of FU. The cumul ative quantity ratio of the FDHU and FU (FDHU/FU) excreted in their urine w ithin 120 min after FU administration was a constant value in all seven pat ients. Based on these results, we believe that our method provides a useful tool for evaluating FU metabolism. (C) 1999 Published by Elsevier Science BN. All rights reserved.