HPLC analysis of some allowable-antibiotic multiresidues in farmed rainbow trout in Iran

This study aimed to investigate the occurrence of antibiotic residues in rainbow trout muscle samples (n = 74) obtained from Iranian trout farms. The levels of the antibiotics were determined by in-house validated HPLC methods. Oxytetracycline, tetracycline, enrofloxacin, ciprofloxacin, and florfenicol residues were detected in 6.76%, 37.8%, 31.1%, 10.8%, and 14.9% of the samples, respectively; while chlortetracycline was not detected. The detected range of concentrations for positive samples was 8.94-81.2 mu g/kg for oxytetracycline, 7.99-98.4 mu g/kg for tetracycline, 6.75-87.4 mu g/kg for enrofloxacin, 5.83-11.5 mu g/kg for ciprofloxacin, and 49.9-313.6 mu g/kg for florfenicol. None of the samples exceeded the maximum residue levels (MRLs) established by the Institute of Standards and Industrial Research of Iran. The co-occurrence of antibiotics was detected in 40.5% of the analyzed samples. The frequency of co-occurrence of enrofloxacin-tetracycline was the highest (16.2%). Despite the fact that concentrations of the analyzed antibiotics in trout samples did not exceed the MRLs, their co-occurrence in such a level could be a serious public health problem.