HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF SULFADIAZINE AND TRIMETHOPRIM IN CHINOOK SALMON MUSCLE-TISSUE

A sensitive high-performance liquid chromatographic (HPLC) analytical procedure was developed for the quantitative determination of sulphadiazine (SDZ) and trimethoprim (TMP) in Chinook salmon muscle tissue. SDZ and TMP were extracted from salmon muscle tissue using solid-phase extraction, and the extract was subsequently subjected to separate HPLC assay for each of the drugs. An Ultrasphere octadecylsilyl ion-pair column (250 x 4.6 mm I.D.) was used for both assays. A mobile phase of methanol-0.05 M phosphate buffer pH 2.5 (17:83), with ultraviolet detection at 280 nm was used for the SDZ assay. A mobile phase of acetonitrile-0.05 M phosphate buffer pH 2.5 (5:95), with ultraviolet detection at 224 nm was used for the TMP assay. The calibration curves for both assays in Chinook salmon tissue were linear over the concentration range of 0.1 to 10 mug/g for SDZ (r2 = 0.9990) and 0.1-15 mug/g for TMP (r2 = 0.9996). The minimum detectable quantities in Chinook salmon muscle tissue for both SDZ and TMP were 0.1 mug/g at signal-to-noise ratios of 10:1. The average recoveries for the drugs from Chinook salmon muscle tissue were 63% for SDZ and 42% for TMP.