分子印迹电化学传感器测定大气中的羟基自由基

Determination of Hydroxyl Radical in Atmosphere by Molecularly Imprinted Electrochemical Sensor

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TiO_2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/TiO_2/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p H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。

p-Hydroxybenzoic acid can be oxidized by hydroxyl radicals（ · OH） to produce electroactive3,4-dihydroxybenzoic acid（ 3,4-DHBA）. Therefore,it can be used as a probe to detect ·OH. In this work,3,4-DHBA/PPy/TiO_2 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,p H 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.