Screening, determination and confirmation of tetracycline residues in chicken tissues using four-plate test, ELISA and HPLC-UV methods: comparison between correlation results

Residues of tetracycline (TC) groups were quantified in 120 broiler chickens carcasses (including breast, liver and thigh tissues) by high performance liquid chromatography (HPLC) and also four-plate test (FPT) and ELISA methods as primary screening tests. Results of FPT showed that 25% of carcasses were polluted by antibiotic residues. The ELISA assay indicated that out of 30 positive samples in FPT, 21 liver, 16 thigh and 12 breast muscle samples were positive for TC residues. Frequency of TC-like residues and their concentration ranges in ELISA-positive samples were determined by HPLC method. In comparison between the results of these methods, the correlation between FPT and HPLC (0.940) was higher than ELISA and HPLC methods (–0.726). Moreover, this study revealed that an inhibition test with a medium at pH 6 which seeded with Bacillus subtilis had highest sensitivity for detecting of TC residues.