Development of monoclonal immunoassays for the determination of lomefloxacin residue

A monoclonal antibody (mAb) 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; hybridomas were prepared by fusing NS0 mouse myeloma cells with splenocytes isolated from immunized BALB/c mouse. Finally, a mAb of L3C8 was selected, which was employed to develop the subsequent immunoassay. Based on the square matrix titration, a representative icELISA curve was established. The dynamic range in assay buffer was from 0.03 to 96.4 ng/mL, with limits of detection (LOD) and IC₅₀ value of 0.01 ng/mL and 0.18 ng/mL, respectively. Except for a little cross-reactivity (16.2%) to ciprofloxacin, this assay showed negligible cross-reactivity to other fluoroquinolones tested. To reduce the matrix effects, the least dilutions for chicken extractions were expected to be 1:10. The results suggest the established immunoassay could be used for detecting lomefloxacin residue in animal samples.