Development Of Colloidal Gold Immunochromatographic Assay For Rapid Detection Of Residues Of Sulfadimidine In Food

Sulfadimidine is often used for the prevention and control of a number of veterinary diseases. As a result, sulfadimidine can be present in food products of animal origin. Sulfadimidine residues in food and animal tissues may be present in minute concentrations but may pose a health threat to consumers. Therefore, it is important to establish a rapid and simple method for the detection of sulfadimidine residues in meat and other animal by-products (honey and eggs) used for human consumption.The colloidal gold strip of sulfadimidine described in this study was developed by means of the competitive immunoassay mechanism. The competitor of sulfadimidine (sulfadimidine-BSA conjugate) was immobilized to the defined detection zone on a nitrocellulose membrane which acted as the capture reagent, and the monoclonal antibody against sulfadimidine was conjugated to colloidal gold particles which served as the detection reagent for the preparation of the one step strips to detect sulfadimidine. With this method, the detection limit of the strip was 10 ng/mL for detecting sulfadimidine in less than 5 min, which had low cross-reactivities to other sulfonamides. The stability test indicated that the test strips can be stored at room temperature for 18 months.The strips could be used for rapid detection of sulfadimidine residues in many kinds of food samples, such as pig muscle, pig liver, pig kidney, chicken muscle, egg, cattle muscle, fish muscle, shrimp muscle and honey. These food samples were spiked with sulfadimidine. The acetonitrile was used as the extract solvent, and the matrix effect could be eliminated by dilution with PB. The LOD of sulfadimidine in nine samples were lower than maximum residue limit of China (MRL 100μg/kg).This method is simple, sensitive, rapid, unexpensive, and specific, which could be widely used for on-site detection of sulfadimidine residues in animal foods including pig muscle, pig liver, pig kidney, chicken muscle, egg, cattle muscle, fish muscle, shrimp muscle and honey on-site.