Development of a polyclonal antibody based icELISA for the determination of lomefloxacin residue

A polyclonal antibody (pAb) based indirect competitive enzyme-linked immunoassay (icELISA) for determination of lomefloxacin (LOM) residue has been developed. For this purpose, NHS ester method was employed to synthesize the artificial antigen of LOM, and anti- serum produced from the immunized rabbits was tested by indirect ELISA and icELISA. By the square matrix titration, an icELISA standard curve was developed. The dynamic range was from 0.062 to 82.5 ng/mL, with LOD and IC₅₀ value of 0.038 ng/mL and 2.2 ng/mL, respectively. Except for a little cross-reactivity (16.2%) to ciprofloxacin, this assay showed negligible cross-reactivity to other fluoroquinolones tested. After optimization, 0.03 mol/L of HCl, or 10% of acetonitrile was used in the assay buffer. Under the 1:20 dilution in poultry, the correlation coefficient (R²) were 0.9572 in chicken, 0.9643 in duck, and 0.9482 in goose. The results suggest the veracity of the immunoassay for detecting LOM residue in foodstuffs.