Abstract:

In this study, a rapid and high sensitive direct competitive enzyme-linked immunoassay (dc-ELISA) method based
on antigen labeled by horseradish peroxidase (HRP) was established and successfully applied to detect fluoroquinolones (FQs)
in animal-derived food. In the direct competitive assay, monoclonal antibody was bound to the surface of a microtiter plate,
and the standards (or the sample) competed with antigen for the antibody binding sites. Under optimized assay conditions,
the IC50 of dc-ELISA was 2.04 μg/L, the limit of detection was 0.15 μg/L, and the linear range was 0.3–15 μg/L. This
method could detect 12 kinds of FQs with recoveries from milk, chicken, fish and shrimp in the range from 70% to 121.5%.

Key words: fluoroquinolones, horseradish peroxidase (HRP)-labeled antigen, multiresidue determination, direct competitive ELISA (dc-ELISA)