基于三聚氰胺膜电催化与酶催化放大的分子印迹电化学传感器测定绿麦隆

以三聚氰胺(MA)作为功能单体, 制备了一种检测环境中农药残留绿麦隆(CH)的分子印迹膜电化学传感器. 基于CH与辣根过氧化物酶(HRP)标记绿麦隆(HRP-CH)的竞争反应实现对CH的检测. 利用聚三聚氰胺膜(PMA)和HRP对过氧化氢的催化效应产生的双放大效应有效地提高传感器检测的灵敏度. 采用计时电流法测量, CH浓度与峰电流差值在0.01～0.8 μmol/L范围内呈现良好的线性关系, 检出限为2.64 nmol/L. 传感器对CH具有很好的选择识别性能.

Molecularly Imprinted Electrochemical Sensors Based on the Double-amplification from the Electro-catalysis of Poly-melamine and the Enzymatic Catalysis of HRP for Chlortoluron Determination

A molecular imprinted electrochemical sensor for the determination of the residue of chlortoluron(CH) in environment was prepared with melamine(MA) as functional monomer.The electropolymerization of poly-melamine-molecularly-imprinted-polymer(PMA-MIP) on the GC electrode was conducted in a 1.0 mol/L H2SO4 by cyclic voltammetry(CV) at room temperature(25 ℃).Then the template molecule(CH) on the PMA-MIP film was removed by nitric acid.The experimental conditions(including electrocatalysis of the MA film,pH effects,incubation and competition times) were optimized.The incubation time chosen for the subsequent experiments was 12 min and 12-min was also recommended as the optimized competition time.The Amperometric i-t curves were recorded during the determination.The detection of CH relied on a competition reaction between CH and horseradish peroxidase labeled chlortoluron(HRP-CH) coupled with the subsequent catalytic reduction of hydrogen peroxide by the poly-MA film.Highly sensitive detection of CH was achieved by the double amplification derived from the electro-catalysis of H2O2 on MA film and the enzymatic effect of HRP.There was linear relationship between the current changes and CH concentration in the range of 0.01～0.8 μmol/L with a detect limit of 2.64 nmol/L by chronoamperometric method.The proposed PMA-MIP sensor displayed excellent analytical performance(e.g.,high sensitivity,good selectivity,and good reproducibility).Some analogues(difenoxuron,neburon,isoproturon and fluometuron) were also used as interferences to examine the selectivity.The changes in the current response of 94-time difenoxuron,62-time neburon,38-time fluometuron and 20-time isoproturon are negligible compared with chlortoluron.In addition,the feasibility of its practical applications has been demonstrated in the analysis of samples of tap water and soil extract solution.Recoveries were ranged from 97.0% to 107.0%,and the RSDs were less than 2%,which can be indicators of good recovery and practicability.