Development Of The Visual Immunoassay Methods For The Detection Of Dimethyl Phthalate

The colloidal gold immunochromatographic rapid test strip,quantum dots immunochromatographic rapid test strip and quantum dots immunoaffinity gel detection column for rapid detection of dimethyl phthalate(DMP)were developed in this work.These methods were rapid,simple and specific enough for reliable and accurate on-site screening DMP in food.Glutaraldehyde was used to synthesis DMP coating antigen(DMP-OVA).The diameter of colloidal gold particles was 20 nm.The pH of colloidal gold solution was adjusted 9 and the optimal amount of antibody(1mg/mL)was 20 ?L.The dilution of gold labeled antibody was 1:5.The diluted solution of secondary antibody and coating antigen were PBS,and dilution were 1:130 and 1:3.Millipore HF135s models of nitrocellulose membrane(NC membrane)was blocked by milk powder solution for 1 h.Sample diluent was PBS.The limit of detection was 100 ?g/L.There was good specificity with no cross reaction with other types of plasticizer.Detection time was less than 10 minutes.The limit of detection was 100-500 ?g/L(?g/kg)for detecting DMP in samples.The quantum dot-labeled antibody(QDs-Ab)was prepared by the active ester method.The molar ratio of quantum dots to the N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide(EDC)and antibpdy was 1:1500:10.The pH of the QDs was adjusted 8.4.Gold standard working solution and PB solution(pH 7.4)mixed by the ratio of 1:4 as sample diluent.The dilution of QDs-Ab was 1:500.The dilutions of coating antigen and secondary antibody were 1:12 and 1:220;conjugate pad was treated with 0.1%PEG 200;sample diluent was PBS.The limit detection of this test strip was 50 jig/L.The method has good specificity and there was no cross reaction with other types of plasticizer,t.Detection time was less than 10 minutes.The limit of detection was 50-150 ?g/L(?g/kg)for detecting DMP in samples.The quantum dot-labeled coating antigen(QDs-OVA-DMP)was prepared by the active ester method.The molar ratio of quantum dots to the EDC and coating antigen was 1:4000:30.Sample diluent solution was concentrated 5-fold PB buffer.The dilution of QDs-OVA-DMP was 1:800.The reaction time was 60s.Number of cleanings times was 5.The limit detection of this test strip was 30 pg/L.There was no cross reaction with other types of plasticizer,the method has good specificity.Detection time was less than 10 minutes.The limit of detection was 30-150 ?g/L(?g/kg)for detecting DMP in samples.The immunoassays in this paper were simple,visual results can be obtained,detection time was short,with good prospects for development.