分子印迹电化学传感器测定大气中的羟基自由基

摘要

p-Hydroxybenzoic acid can be oxidized by hydroxyl radicals ( · OH) to produce electroactive 3,4-dihydroxybenzoic acid (3,4-DHBA). Therefore, it can be used as a probe to detect ·OH. In this work, 3,4-DHBA/ PPy / TiO2 molecularly imprinted polymer film was prepared for indirect determination of ·OH based on its recognition ability for 3,4-DHBA. The sensor was constructed by using pyrrole as the functional monomer and 3, 4-DHBA as the template molecule. The sensor was characterized by scanning electron microscope and different electrochemical methods. The preparation and determination conditions, such as the electropolymerization cycle number, pH value in the electropolymerization process, and elution time, were optimized. Under the optimal conditions, a linear range of 1. 0×10-8-1. 0×10-6 mol/ L was obtained for 3,4-DHBA and the detection limit was down to 4. 2×10-9 mol/ L (S / N = 3). This new approach was of low cost and convenience, and was successfully applied to measure the concentration of ·OH in the atmosphere.%对羟基苯甲酸可以作为分子探针被羟基自由基(·OH)氧化,产生具有电化学活性的3,4-二羟基苯甲酸(3,4-DHBA).根据此原理,本研究以吡咯为单体,3,4-二羟基苯甲酸为模板分子,在纳米TiO2修饰的玻碳电极上电聚合制备分子印迹聚合物膜修饰电极(3,4-DHBA-PPy/TiO2/GCE),实现对·OH的间接测定.通过扫描电子显微镜(SEM)和电化学方法对此传感器进行表征,优化了电聚合圈数、电聚合体系pH值、洗脱时间、吸附时间等条件.在优化条件下,标准物3,4-DHBA氧化峰电流大小与其浓度在1.0×10-8～1.0×10-6 mol/L范围内具有良好的线性关系,检出限为4.2×10-9 mol/L(S/N=3).将传感器用于大气中·OH浓度的测定,结果良好,是一种低廉、便捷、新颖的检测·OH的方法.