| Aming at the present popular food safety issues,two categories of molecularly imprinted electrochemical sensors based on the specificity of molecularly imprinted polymers and the advantages of rapid analysis of electrochemistry were fabricated for the respective detection of triazole and pyrethroid pesticide residues.Selecting the similar molecular structure but the different molecular weight pesticide as the template molecule and investigating the effect of molecular weight on the properties of molecularly imprinted electrochemical sensor.Simultaneously,various kinds electrochemical characterization methods were used for studying the preparation mechanism and response characteristics of the proposed sensor.The two categories of sensor have the advantages of good selectivity,high sensitivity,rapid and accurate detection and low cost,and have important research value.A molecularly imprinted electrochemical sensor based on molecular interactions was prepared by electropolymerization using o-phenylenediamine?OPD?with double functional groups as functional monomer and bitertanol as template molecule.The influence of electropolymerization cycles,electropolymerization potential and the proportion of template molecule and functional monomer on the sensor performance was investigated by electrochemical methods.The response characteristic of the molecularly imprinted sensor was studied by cyclic voltammetry?CV?and differential pulse voltammetry?DPV?.The results showed that the sensor has good selectivity towards bitertanol and structural analogues,the potassium ferricyanide?K3[Fe?CN?6]?was used as the probe for the indirect determination of bitertanol.A good linear relationship between the concentration of bitertanol and relative peak current change of K3[Fe?CN?6]was obtained with a range from 1.0×10-6 mol/L to 2.0×10-5 mol/L,the detection limit was3.0×10-7mol/L,and the sensor was applied to detection of bitertanol pesticide residues in foods.A sensitive molecularly imprinted electrochemical sensor with POPD/OAP composite membrance using myclobutanil as template molecule was prepared by CV method in the OPD and OAP mixed functional monomers solution.The combination form and effect intensity between myclobutanil and OPD or OPA were studied by UV spectra.Under the optimum conditions,the response performances of the sensor for myclobutanil was investigated by CV,DPV and electrochemical impedance spectroscopy?EIS?.The myclobutanil concentration can be indirect determined by recording the redox currents of K3[Fe?CN?6].The results showed that the sensor has high sensitivity and good selectivity to the myclobutanil.Finally,the sensor was successfully applied to detection of myclobutanil pesticide residues in foods,the average recoveries were between 83.0%and95.2%with the relative standard deviations?RSDs?was less than 2.1%?n=5?.A molecularly imprinted electrochemical sensor was fabricated based on electrodeposited chitosan for determination of cyhalothrin.The effect of electrodeposition potential and electrodeposition time on the sensor performance was investigated by electrochemical methods.Cyhalothrin molecularly imprinted electrochemical sensor was prepared and used for determination of cyhalothrin in foods under the optimal conditions including the electrodeposition potential of-1.5 V and electrodeposition time of 5 min.A sensitive molecularly imprinted electrochemical sensor using tetramethrin as template molecule was prepared by electropolymerization of OAP on glassy carbon electrode.Optimization of the preparation conditions and the electrochemical response performance to the different concentrations of tetramethrin were investigated.The method of potential induction elution template molecule was studied.Finally,the template molecule was removed under applying-0.3 V on the electrode and inducing elution 5 min in soslution of 0.5 mol/L sulfuric acid-acetonitrile=1:5?V:V?,and the sensor was applied to detection of tetramethrin in foods. |
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