The Studies On Recognition Of Pyrethroids In Food Using Fragment Imprinted Technology

In this paper, a series of imprinted polymers for recognition of pyrethroids weresynthesized by using fragment imprinting technology. Fragment imprinting polymers wereprepared by bulk, suspension and precipitation polymerization. The conditions of experimentwere optimized and binding characteristics were evaluated. Scanning electron microscopywas employed to monitor morphology of the polymers. It was also evaluated by solid phaseextraction column packed of polymers combined with gas chromatography to determine tracepreservatives in honey sample.1. Two pseudo-template molecules have been selected from analogues of the pyrethroids.Compared with the red-shifted of maximum absorption wavelength and the rebinding test,phenyl ether-biphenyl was chosen as the pseudo-template finally.2. Molecularly imprinted polymers were prepared by bulk polymerization, using phenylether-biphenyl as the pseudo-template,4-Vinylpyridine as the functional monomer, ethylenedimethacrylate as the linking agent, chloroform as porogenic solvents andazobisisobutyronitrile as the thermal polymerization initiator. The optimizational conditionwas obtained by orthogonal experiments, the ratio of pseudo-template, functional monomer,crosslinker was1:6:20, the reaction temperature was70℃. The maximum adsorption wasgotten under the optimizational conditions. The absorption amount of dursban, bifenthrin,fenpropathrin, permethrin, cypermethrin, fenvalerate for molecularly imprinted polymerswere389.2,474.4,467.3,407.5,458.7and447.4μg g-1, respectively. While thenon-imprinted polymers were254.6,282.1,271.7,284.4,226.2and213.6μg g-1, respectively.The polymers were loaded into the solid phase extraction cartridge. The optimum experimentshowed that water mixtures containing10%of acetone was chosen as the loading solvent,water mixtures containing50%of acetone was chosen as the washing solvent, methanol wasselected as the sample elution solvent. The method of the determination of pyrethroids inhoney samples has been developed using homemade solid phase extraction cartridge. Thelinear range of the method was0.002-0.20μg mL^-1and the limit of detection was0.025μgmL^-1. The recovery of matrix spiked samples were98.7%,93.2%,91.6%and the relativestandard deviation （RSD） were4.37%,3.65%,6.17%at levels of0.05μg mL^-1,0.1μg mL^-1,0.2μg mL^-1, respectively. 3. Molecularly imprinted microspheres were prepared by suspension and precipitationpolymerization. The optimizational condition was obtained by orthogonal experiments: usingprecipitation polymerization, the ratio of template molecule （phenyl ether-bipheny）,functional monomer （methacrylic acid）, crosslinker （ethylene dimethacrylate） was1:6:40, thereaction temperature was70℃. The maximum adsorption was gotten under theoptimizational conditions. The absorption amount of bifenthrin, fenpropathrin, permethrin,cypermethrin, fenvalerate, dursban, pentachloronitrobenzene for molecularly imprintedmicrospheres were632.3、518.24、575.69、558.05、537.81、385.03and352.57μg g1whilethe non-imprinted microspheres were352.35、331.05、289.32、253.88、364.14、334.59and295.32μg g^-1, respectively. The polymers were loaded into the solid phase extractioncartridge. The method of the determination of preservatives in honey samples has beendeveloped using homemade solid phase extraction cartridge. The linear range of the methodwas0.002-0.50μg mL^-1and the limit of detection was0.011μg mL^-1. The recovery of matrixspiked samples were96.1%,94.2%,95.6%, and the relative standard deviation （RSD） ofwere3.73%,5.16%,4.04%at levels of0.10μg mL^-1,0.20μg mL^-1,0.40μg mL^-1,respectively.