DIRECT DETERMINATION OF 7-HYDROXYCOUMARIN AND 7-HYDROXYCOUMARIN-GLUCURONIDE IN URINE BY USING CAPILLARY ELECTROPHORESIS

A method has been developed for the direct determination of 7-hydroxyc oumarin (7HC) and 7-hydroxycoumarin-glucuronide (7HCG) in urine withou t sample clean-up. Separation was carried out in 90% 100 mmol l(-1) ph osphate buffer, 11 mmol l(-1) deoxycholic acid (sodium salt) and 10% a cetonitrile, on a 47 cm uncoated silica capillary at 20 kV with detect ion of the analytes at 320 nm, The linear detection range for concentr ation versus peak area for the assay is from 0 to 100 mu g ml(-1) for both analytes, with a limit of quantitation of 2 mu g ml(-1) for 7HC a nd 5 mu g ml(-1) for 7HCG in urine. Inter- and intra-assay results sho wed s(r) values in peak areas of between 0.5 and 13%, The method was a pplied to the direct determination of 7HC and the glucuronide conjugat e in urine from two volunteers administered with 250 mg of coumarin, T he samples were also analysed by another CE method and by using HPLC, There was no statistical difference between the results determined by each of the methods, Up to 83% of the coumarin administered was excret ed as 7HC or 7HCG. The majority of the 7HC excreted was in the glucuro nide form (98%) with 2% occurring as free 7HC.