| Four visual fluorescence immunochromatographic assays for rapid detection of bisphenol A(BPA)and dimethyl phthalate(DMP)were established in this paper,which are used to visualy and rapidly detect two plasticizers in food and environment samples.In the development of quantum-dot-labeled immunochromatographic test strip for BPA,the activated ester method was used to prepare quantum dots-antibody(QDs-Ab)conjugates,the optimum coupling molar ratio of quantum dots,antibody and activators is 1:4:1500,the optimum pH of the borate saline buffer is 8.3.The dilution of goat anti rabbit IgG and coating antigen are 1:400 and 1:12 respectively.The type of nitrocellulose membrane is Milipore HF135s.The visual detection limit of this method is 50 μg L-1.There is no cross reaction with other BPA structural analogs,which means the specificity of this method is good.The visual detection limit of BPA in samples is 10 μg kg-1(or μg L-1).In the development of fluorescence quenching immunochromatographic test strip for BPA,the particle size of colloidal gold which is prepared by the method of trisodium citrate reduction is 18 nm to labeled antibody,the optimal amount of K2CO3 added to prepare gold labeled antibody is 10 μL,and the optimum amount of antibody added is 15 L.The dilution of the coating antigen and the quantum dots-bovine serum albumin(QDs-BSA)conjugate are 1:12 and 1:5.7,respectively.The type of nitrocellulose membrane is Milipore HF135s.The visual detection limit of this method is 20 μg L-1.There is no cross reaction with other BPA structural analogs,which means the specificity of this method is good.The visual detection limit of BPA in samples is 4 μg kg-1(or μg L-1).The results of the established method are consistent with those determined by HPLC,the accuracy of this motheds is quite high.In the development of fluorescence quenching immunochromatographic test strip for DMP,the optimal amount of K2CO3 added to prepare gold labeled antibody is 5 μL,and the optimum amount of antibody added is 10 μL.The dilution of the coating antigen and QDs-OVA conjugate are 1:2 and 1:6,respectively.The type of nitrocellulose membrane is Milipore HF135s.The visual detection limit of this method is 20 μg L-1.There is no cross reaction with other phthalates,which means the specificity of this method is good.The visual detection limit of DMP in samples is 4 μg kg-1(or μg L-1).The results obtained by the established method are consistent with those obtained by GC-MS,the accuracy of this motheds is quite high.On the basis of the methods of single component test strip,the fluorescence quenching immunochromatographic test strip for multi residue of DMP and BPA was developed in this paper.The connection modes of two kinds of gold labeled antibodies and the sequence of two antigen are optimized.It was determined that the two antibodies are labeled with colloidal gold individually and then mixed these two compounds for detection.The order of antigen on nitrocellulose membrane from top to bottom is control line,DMP test line and BPA test line.The detection limits of DMP and BPA in this method are 100 μg L-1 and 50μg L-1,respectively.The visual detection limits of DMP and BPA in water samples are 100 μg L-1 and 50μg L-1 respectively. |
