Study On The Immunochrographic Test Strip For The Determination Of Tetracycline

In this study, a colloidal gold immunochromatographic rapid test strip was developed and effectively applied for repid determination of tetracycline in animal-derived food.The coating antigen was prepared by conjugating to cationic bovine serum albumin (cBSA) according to the formaldehyde method. Anti-tetracycline polyclonal antibodies were purified by protein A-sepharose4B. Gold chloride was reduced using sodium citrate to make colloidal gold(20nm). And the optimum pH of gold labled antibody was8.0and the optimum antibody was24μL. The coating antigen (TC-cBSA) and goat anti-rabbit secondary antibody were immobilized on nitrocellulose membrane as the test line and control line. The polyclonal antibody was solidified to glass optimal conditions with dilutions of TC-cBSA, goat anti-rabbit IgG, gold labeled antibodies of1:1,1:100and1:3, respectively. The detection limit of the tetracycline test strip:the visual detection limits were40μg/L. The detection time was5minutes.Milk, honey, beef, pork, chicken, squid, big eye snapper, halibut, salmon, sea bass and shrimp were used as real samples. The visual detection limits of the tetracycline in in all the samples were lower than all the maximum residue limits (MRLs). The visual detection limit in milk was40μg/L. The visual detection limit in the other ten samples was80μg/kg. The established tetracycline immunochromatographic analysis method was consistent with ELISA, verifying its high accuracy.The immunochromatographic rapid test strips stayed at room temperature for3months. Several days were used to detect tetracycline without obvious change. This method has the characters of high sensitivity, specificity, fast, convenience and reliability, which can be used for mass screening of tetracycline residues in animal food on-site.This research also preliminarily explored grapheme oxide-colloidal gold immunochromatographic test strip for tetracycline determination. Gold chloride was reduced with sodium citrate to make GO-colloidal gold with the optimum pH of gold labled antibody at8.0and the optimum antibody at24μL. The visual detection limits were20ug/L, which was better than the traditional colloidal gold test strip.