HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF TRIMETHOPRIM AND SULFADIAZINE IN MEDICATED FISH FEEDSTOCK

A high performance liquid chromatographic (HPLC) method for the determination of sulphadiazine and trimethoprim in medicated fish feedstock is described. It is based on the extraction of the drugs into methanol followed by separation on a mu-Bondapak column using an aqueous acetonitrile mobile phase of pH 3.0. The method was validated by determining intra- and inter-assay precision and the coefficient of variation was found to be less than 8% for both drugs. Calibration curves were linear over the range 160-4000-mu-g drug per g of feedstock and the method was applied to the determination of a commercial feedstock formulation.