Abstract: The aim of this study was to detect fluoroquinolones (FQs), in chicken, chicken liver, and fish, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed based on immunomagnetic beads for sample clean-up and purification. (Method) Optimizing the addition amount of monoclonal antibody, coupling time, pH of buffer solution, the addition amount of quinolone antigen, capture time of antigen, temperature, and encapsulation condition of immunomagnetic beads, an icELISA method based on immunomagnetic beads clean-up was preliminarily established. Results were as follows:1) In 1 mg magnetic beads, the optimal coupling amount of sarafloxacin (SAR) monoclonal antibody was 15 μg, coupling time was 60 min, pH was 4.4; 2) The optimal antigen dosage was 1 ng·mL^-1, capture time was 40 min, and the buffer ion concentration was 0.01 mol·L^-1 PBS. The IC₅₀ was 0.73 ng·mL^-1 with a linear range of 1.0-3.2 ng·mL^-1; 3) The detection limits of fluoroquinolones in chicken, chicken liver and fish were less than 1.33, 2.17 and 2.31 μg·kg^-1, and the recoveries ranged from 76.83%-98.70% with intraday and interday variation coefficients lower than 15%. The recovery results were further confirmed using liquid chromatography-tandem mass spectrometry. The results suggest that, compared with the traditional instrumental detection method, this method can improve the simplicity, selectivity, and detection efficiency of fluoroquinolones, and provide a new idea for fluoroquinolones residue detection.

Key words: enrichment of immunomagnetic beads, quinolones, monoclonal antibody, indirect competitive enzyme-linked immunosorbent assay (icELISA)