A sensitive chromatographic strip test for the rapid detection of enrofloxacin in chicken muscle

A sensitive colloidal gold immunochromatography assay using a specific monoclonal antibody was developed for the rapid detection of enrofloxacin (ENR) residues in chicken muscles. Anti-ENR antibodies with high sensitivity and specificity are generated by immunising BALB/c mice with well-characterised ENR-bovine serum albumin conjugate. An orthogonal L-9(3)(3) test was designed, and various parameters that influenced the assay performance were investigated and optimised. Under the optimised conditions, the cut-off limits of semi-quantitative test strips for ENR were found to be 3 ng/mL in phosphate-buffered saline and 8 mu g/kg in chicken muscle. The ENR test strips showed a 6% cross-reactivity with ciprofloxacin, 3% with norfloxacin, less than 1% with ofloxacin and sarafloxacin and 0.1% with the other eight fluoroquinolones including enoxacin, difloxacin, danofloxacin, pefloxacin, lomefloxacin, sparfloxacin, oxolinic acid and flumequine. Consistent results are produced from the parallel analysis of ENR-contaminated chicken muscle extracts using test strips and ELISA.