Development of an indirect competitive enzyme-linked immunosorbent assay for detection of danofloxacin residues in beef, chicken and pork meats

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of danofloxacin (DAN) in beef, chicken and pork muscle meats using polyclonal antisera. The half-maximum inhibition concentration (IC50) and limit of detection (LOD) of the ELISA in assay buffer were 5.4 and 0.10 ng/ml, respectively. The assay showed little cross-reactivities with quinolones structurally related to DAN. No significant changes were found for IC50 values when the pH values of the assay buffer ranged from 5 to 7 and NaCl concentrations ranged from 1 to 4%. The ELISA can tolerate up to 10% methanol, 2.5% acetone or 2.5% acetonitrile in the assay buffer without significant effects on IC50. The average recoveries of DAN from fortified control beef, pork and chicken samples were in the ranges of 85-101%, 87-101% and 92-105%, respectively. The average intra-assay and inter-assay coefficients of variation were in the ranges of 2-7% and 3-12%, respectively.