Development of an ultrasensitive ic-ELISA and immunochromatographic strip assay for the simultaneous detection of florfenicol and thiamphenicol in eggs

Abstract

An ultrasensitive monoclonal antibody-based gold nanoparticle immunochromatographic strip assay and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) were developed to detect florfenicol (FF) and thiamphenicol (TAP) in egg samples. The ic-ELISA, with optimized pH, methanol content and sodium chloride content, exhibited an IC50 value of 0.2 ng/mL for FF and 0.27 ng/mL for TAP, with the working range of 0.05–0.77 and 0.05–1.42 ng/mL, respectively. The optimized ic-ELISA showed negligible cross-reactivity with other phenols and broad-spectrum antibiotics. The recoveries in egg samples using the ic-ELISA ranged from 84% to 115% with a coefficient of variation of less than 5%. Based on this monoclonal antibody, a rapid and ultrasensitive immunochromatographic strip assay was developed with a cutoff value of 1 ng/mL for FF and TAP. Our results indicated that both developed methods were highly useful for screening FF and TAP in eggs.