Abstract: A time-resolved fluoroimmunoassay (TRFIA) was developed for the rapid and sensitive detection of enrofloxacin (ENR). In indirect TRFIA format, the envelope antigen composed of ENR and ovalbumin (OVA) was coated onto the microplate, and followed by the incubation with free ENR and anti-ENR polyclonal antibody. A goat anti-rabbit IgG conjugated with europium (Eu3+) was used for the detection. The intra-assay CV (coefficient of variation) of the developed method was less than 10% and the inter-assay CV less than 15%. The average recovery rate was 91.62% and the sensitivity was 5 ng/L. The antibody had a linear response over the range from 0.01μg/L to 100μg/L. The ED20, ED50 and ED80 (80%, 50% and 20% effective doses) were 0.088, 3.40μg/ L and 32.81μg/ L, respectively. The high stability and broad detection range allows the TRFIA method to have promising application prospects.

Key words: enrofloxacin, time-resolved fluoroimmunoassay, veterinary drug residues