Study On The Colloidal Gold Immunochromatographic Rapid Test Strip For The Determination Of Sulfonamides Residues

A competitive assay based on the principle of immunoassay using colloidal gold as tracer for the rapid on-site detection of sulfonamides residues in food samples was studied. After optimizing the various factors and conditions of the test, using the anti-sulfonamides polyclone antibody, S₄-OVA, the anti-SMZ antibody and SMZ-OVA, the colloidal gold immunochromatographic rapid test strip was developed for the determination of sulfonamides residues.Gold chloride was reduced with sodium citrate to make 40 nm colloidal gold, then it was labeled to the polyclonal antibody after identification. The hapten-OVA and goat anti-rabbit IgG were dispense 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 SMZ test strip was 1 ug/L, the limits of detection of sulfonamides (STZ, SIZ, SME, SMPD, SP) were 2,2, 5, 5, 5μg/L.Pig muscle, chicken muscle, milk and fish muscle samples were used as real sample (determined to be free of sulfonamides by HPLC) for analysis. These food samples were spiked with sulfonamides. For the one-step strip test, the methanol was used as the extract solvent, and the matrix effect could be removed by dilution with PBST. The LOD of five sulfonamides in four samples were equal to or lower than maximum residue limit (MRL, 100μg/kg). The LOD of SMZ in four samples was equal to or lower than maximum residue limit (MRL, 20μg/kg).The established method was validated by the instrumental method of HPLC. The results obtained by test strip were coherence with the results obtained by HPLC. The results indicated that the test strips can be applied in the rapid detection of sulfonamides residues.The immunochromatographic rapid test strips were placed at 4℃and 37℃for several days and then were used to detect the sulfonamides.The stability test indicated that the reliability of test strips were good at 4℃within 6 months.The method established is sensitive, rapid and simple, and the results could be obtained within 10 minutes. All the results proved that the two test strips could be widely used to detect the sulfonamides residues in animal foods on-site.