Development of a lateral flow colloidal gold immunoassay strip for the rapid detection of enrofloxacin residues.

A rapid immunochromatographic lateral flow test strip of competitive format has been developed using a gold-conjugated monoclonal antibody for the specific determination of enrofloxacin (ENR) residues in chicken muscles. For this purpose, a specific monoclonal antibody (mAb) for ENR was generated and characterized. The mAb showed negligible cross-reactivity with other related compounds. Using ENR standards prepared in chicken muscle extracts from 0 to 24.3 ng/mL (microg/kg), the method indicated that the detection limit of the test strip, as measured in a strip scanner, was as low as 0.138 microg/kg of ENR and the half-maximal inhibition concentration (IC(50)) was 0.935 microg/kg. For samples spiked at 10, 20, and 30 microg/kg, the recovery was between 85.3 and 96.1% and the coefficient of variation [CV (%)] was between 4.5 and 7.91%. Parallel analysis of muscle samples from chickens fed ENR showed good comparable results obtained from the test strip and LC-MS. Each test requires 5-10 min. The data indicate that the method has high sensitivity, specificity, and the advantages of simplicity and speed of performance. Therefore, the test strip provides a useful screening method for quantitative, semiquantitative, or qualitative detection of ENR residues in chicken muscles.