SIMULTANEOUS DETERMINATION OF SULPHAMONOMETHOXINE AND ITS N-4-ACETYL METABOLITE IN BLOOD-SERUM BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH DIRECT-INJECTION

A high-performance liquid chromatographic method with direct injection has been developed for the simultaneous determination of sulphamonome thoxine and its N-4-acetyl metabolite in serum of animals and fish. A HISEP shielded hydrophobic-phase column (15 cm x 4.6 mm I.D.), a mobil e phase of 0.05 M citric acid-0.2 M disodium hydrogenphosphate-acetoni trile (70:15:15, v/v), and ultraviolet detection at 265 nm were used. The standard calibration curves in serum df chicken, pig, cattle, rain bow trout and yellowtail were linear over the range 0.5-20 mu g/ml. Th e recoveries of sulphamonomethoxine and its N-4-acetyl metabolite from all serum samples determined at different concentrations (0.5, 2.0 an d 10.0 mu g/ml) were 93-103% and 90-103%, respectively. The lowest mea surable sulphamonomethoxine and N-4-acetyl metabolite concentrations w ere 0.04 and 0.1 mu g/ml, respectively, for all serum samples.