Development of a Polyclonal Antibody Based iCELISA Method for Detecting Marbofloxacin Residue

An icELISA immunoassay for determination of marbofloxacin (MAR) residue has been developed. For this purpose, modified EDC technology was employed to synthesize the immunogen and coating antigen of MAR. UV-vis spectrum and SDS-PAGE identification showed that the artificial antigen was conjugated successfully. New Zealand white rabbits were used to produce anti-MAR polyclonal antibody. Based on the square matrix titration, an icELISA method was established. The dynamic range in assay buffer was from 0.18 to 153.6 ng/mL, with LOD and IC50 value of 0.11 ng/mL and 6.2 ng/mL, respectively. Except for a slight cross-reactivity (16.4%) to ofloxacin, this assay showed negligible cross-reactivity to other FQs tested. To reduce the matrix effects, the least dilutions for muscle extractions were expected to be 10- and 20-fold, for beef and pork, respectively. The results suggest the established immunoassay could be used for detecting of marbofloxacin residue in animal samples.