OXYTETRACYCLINE, SULFADIMETHOXINE, AND ORMETOPRIM RESIDUES IN CHANNELCATFISH BY HPLC

HPLC methods and modified extraction procedures were used to analyze r esidues of oxytetracycline (Terramycin, OTC) or sulfadimethoxine (SDM) and ormetoprim (OMP) in channel catfish fed OTC or Romet-30 under con trolled conditions. Mean recovery rates in fish muscle were 92.5% for OTC over concentrations of 0.05-1.0 ppm and 86.3% for OMP and 87.9% fo r SDM over 0.05-5.0 ppm. SDM and OMP were rapidly depleted from large catfish (about 345g) after 5 days feeding with Romet-30 at 50-100 mg/k g body weight. By day 2 post-treatment, no residue was detected. Resid ues of OTC, SDM and OMP were also detected in fingerling channel catfi sh (about 20.3g) after 4 and 8 wk of feeding with Romet-30 or OTC at 1 2.5, 25, or 50 mg/kg body weight, but not after a S-wk-withdrawal peri od.