Development Of The Colloidal Gold Mmunochromatographic Rapid Test Strip For The Determination Of Enrofloxacin Residues

In this paper, the colloidal gold immunochromatographic rapid test strip was developed for the determination of Enrofloxacin residues, which was effectively applied to identify trace Enrofloxacin in animal products, animal metabolites and enviromental samples.The coating antigen was prepared by conjugating Enrofloxacin to OVA according to the mixed acid anhydride method. Anti-Enrofloxacin polyclonal antibodies were purified by protein A-sepharose4B. Gold chloride was reduced with sodium citrate and sodium borohydride to make17nm colloidal golds, which was coupled with the anti-Enrofloxacin polyclonal antibodies as immuno-colloidal gold after identification by transmission electronic microscope. The hapten-OVA and goat anti-rabbit IgG were dispensed on test line and control line respectively and the polyclonal antibody was solidified to glass fibers to prepare immunochromatographic strips.The limit of detection of Enrofloxacin colloidal gold immunochromatographic assay was5μg/L. When the concentration of fifteen kind of fluquinolone medicines and eight kind of common veterinary medicines was1000μg/L, the effect of cross-reactivity could be ignored, which validated the specificity of the test.Nine kind of animal products, pond water and pig urine, determined to be free of the enrofloxacin, were spiked at three concentrations of50,100,200μg/L. After simple pre-treatment, the samples were directly used for analysis by colloidal gold immunochromatographic assay. The visual detection limit of the ENR in spiked milk, ponder water and pig urine were5-25μg/L.The visual detection limit of the ENR in other spiked animal products was50μg/kg. The visual detection limit of the ENR in all the samples were lower than all the Maximum residue limits (MRLs). The results obtained by Colloidal gold immunochromatographic assay were coherence with the results obtained by ELISA.The process of detection is simple, rapid and convenient. The results can be visually read by eyes without instrumentation. The stability and simplicity make it feasible to be detected in the animal products, animal metabolites and enviromental samples.