Oxytetracycline residues in cultured white shrimp tissue by HPLC and a microbial receptor assay

The residue depletion of oxytetracycline (OTC) from muscle tissue of cultur ed shrimp (Penaeus vannamei) was evaluated. OTC was measured using high per formance liquid chromatography (HPLC) and a microbial receptor assay. Sampl es were taken on days 7, 14 and 21 during the treatment and 23, 25 and 28 a fter the treatment, OTC was detectable in all groups after 7 days depletion time at concentrations of 0.28, 0.19 and 0.05 mu g/g for diets containing 500, 250 and 100 mg/kg OTC, respectively, Results by the microbial receptor assay were in good agreement with those by HPLC.