| Aming at the present popular food safety issues,three 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 tetracycline antibiotics,exogenous estrogen and sulfa antibiotics drugs residues.Selecting the similar molecular structure but the different molecular weight pesticide as the template molecule,optimizing the functional monomer,molecularly imprinted electrochemical sensors with good imprinting effect were prepared by electropolymerization.Simultaneously,various kinds electrochemical characterization methods were used for studying the preparation mechanism and response characteristics of the proposed sensor.Combined with nano material modified electrode technology,the sensor performances were further improved.The three categories of sensors 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 the phosphoric buffer solution as electropolymerization medium,o-phenylenediamine(OPD)with double functional groups as functional monomer and tetracycline as template molecule.In the experiment,the HAc-Na Ac buffer solution containing 1 mol/L KCl and 5 mmol/L K3[Fe(CN)6]was used as characterization solution.The influences of electropolymerization cycles,electropolymerization potential and the proportion of template molecule and functional monomer on the sensor performances were investigated by electrochemical methods.The electrochemical sensor response characteristics were researched,and the preparation and detection conditions of the sensor were optimized by differential pulse voltammetry(DPV)and cyclic voltammetry(CV).The sensor had a good selectivity under the optimal conditions,the good linear relationships between DPV peak current difference and the concentrations of tetracycline,oxytetracycline and doxycycline hyclate were found in the range of 0.002?0.02 mmol/L with the detection limits between 6.0×10-7 and 7.5×10-7mol/L.The sensor in methanol-H2SO4 solution was renewable.The tetracycline,etracycline and doxycycline residues in real samples,such as milk and pork,were detected by the sensor,the average recoveries were between 82.8%and 97.4%,the relative standard deviations(RSD)were less than 4.53%.This sensor was suitable for rapaid detection of tetracylines in real samples simple,sensitive,low cost,and it had a good application prospect.A novel electrochemical sensor was constructed for diethylstilbestrol(DES)detection based on molecularly imprinted polymer(MIP)membranes on a glassy carbon electrode(GCE)modified with carboxyl-multi-walled carbon nanotubes(CMWNTs)and aunanoparticles(Au NPs).P-aminothiophenol(P-ATP)and DES were assembled on the surface of the modified GCE by the formation of Au–S bonds and hydrogen-bonding interactions,and polymer membranes were formed by electropolymerization in a polymer solution containing p-ATP,HAu Cl4,tetrabutylammonium perchlorate(TBAP)and the template moleculer DES.50%ethanol-0.1 mol/L sulfuric acid were used to elute template molecules.The imprinted effect and analysis performance of the sensor were researched by cyclicvoltammetry(CV)and differential pulse-voltammetry(DPV).The imprinted sensor was applied to the rapid detection of DES in food.The results showed that the linear response range of the MIP sensor was 1.0×10-9 mol/L?1.0×10-5 mol/L,the limit of detection(LOD)was 3.3×10-10mol/L,the recovery was between 83.1%and 97.6%.The sensor has the advantages of simple operation,rapid detection,high sensitivity,low cost,high sensitivity and anti-interference ability and good stability,it suitable for rapid detection of DES in real samples,and it has a good application value.A molecular imprinted electrochemical sensor was prepared based on the gold nanoparticles and carboxylated multi walled carbon nanotube modified electrode,using sulfadiazine sodium tetracycline as template molecule and o-aminophenol as functional monomer.The combination form and effect intensity between template molecule and functional monomer were studied by UV spectra.Optimization of the preparation conditions and the electrochemical response performance were investigated.The method of potential induction elution template molecule was studied.Finally,the template molecule was removed under applying-0.2 V on the electrode and inducing elution 6 min in soslution of 0.5 mol/L sulfuric acid-methanol=4:1(V:V).The sulfadiazine concentration can be indirect determined by recording the redox currents of K4[Fe(CN)6]/K3[Fe(CN)6],The results showed that the sensor has high sensitivity and good selectivity to the sulfadiazine,the average recoveries were between 82.9%and98.8%with the relative standard deviations(RSDs)was less than 4.0%(n=5),and the sensor was applied to sensitive and rapid detection of sulfadiazine in animal derived food. |
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