Development And Application Of The Colloidal Gold Immunochromatographic Test Strip For Rapid Detection Of Sulfonamides Residues In Swine Urine

A rapid colloidal gold immunochromatographic method was a novel immunoassay that has been a widely used for veterinary medicine. The rapid detection of Sulfonamides(SAs) residue was have played an important role in veterinary drug residue detection.This research was based on the former study of GICA in our laborary, though improving the method to develop GICA for detection of sulfonamides in swine urine. The results of this study were as following:1.Using mixture of 15nm and 25nm labeled colloidal gold served as tracer; 1.0 mg/mL anti-SDL IgG monoclonal antibody (McAb) was conjugated with colloidal gold, and the idea concentration is 77μg/mL for the conjugation; 0.33 mg/mL artificial antigen HSA-SDL(1:20) and 1.0 mg/mL rabbit anti-mouse IgG polyclonal antibody were immobilized on the nitrocellulose membrane as test line and control line for the preparation of colloidal gold immunochromatographic assay to Sulfonamides(SAs). The result shows that the strip has good crossing for Sulfamonomethoxine(SMM)、Sulfametoxydiazine(SMD)、Sulfadimethoxine(SDM)、Sulfadiazine(SD), and the detection was 2 ng/mL, consistent with national dose limited standard:100 ng/mL2.Pigs feed with the therapeutic dose of SMM and detected SMM residues in swine urine with test strips. The recovery rates in swine urine were 62.9%-106.7%, and the coefficient variation were lower than 15%. The result of animal experiment shows that SMM residues in swine urine were more than 100 ng/mL and read for positive detected by test strips in the first, second, third, fourth day of feeding drug and the first,second day after feeding drug, but it was negative in swine urine without feeding drugs; SMM residues in swine urine were less than 100 ng/mL and read for negative detected by test strips in the third, fourth, fifth, sixth day after feeding drug. It shows that the residue of SMM could be converted to negative after 3 days. This method has good agreement with ELISA Kit:85.7%(24/28)for positive samples, 87.1%(27/31)for negative samples, and 92.7% [(24+27)/55] for all animal experiment samples.3.A total of 200 urine samples were collected from some pig farms, which were detected with a rapid test strip of SDL. The residual concentrations below 100 ng/mL or higher than 100 ng/mL judged as negative (-) or positive (+). The test strip results indicated that 1 positive sample was detected, and the remaining were negative. This positive sample and randomly selected 3 negative samples were detected with ELISA kit method. The detection results were:0.051、0.251、0.342、0.549 and their residual concentrations were:126.28 ng/mL,87.35 ng/mL,73.86 ng/mL,50.43 ng/mL which calculated with EILSA standard curve:y=-0.5373x+0.8275, R2=0.9578. This indicates the two methods have 100% agreement.