Optimization and Validation of an Indirect Competitive ELISA for Detecting Enrofloxacin Residue

This article aimed to optimize a polyclonal antibody based indirect competitive ELISA (icELISA) and compare between the icELSIA method and the LC-MS technology for the determination of enrofloxacin (ENR) residue. Based on the square matrix titration, linear range of the icELISA was from 0.006 to 31.5 ng/mL, with LOD and IC50 values of 0.003 ng/mL and 0.45 ng/mL, respectively. After optimization, 0.03 mol/L of HCl was used in the assay buffer and this ELISA system can tolerate acetonitrile not higher than 10%. The recoveries of ENR were in the range of 98.3-127.5%, 85.7-112.5% and 97.4-103.8% for chicken muscle, liver and kidney. The correlation coefficients (R2) of the ELISA and LC-MS data were 0.9472 in muscle, 0.9843 in liver, and 0.9382 in kidney, respectively.