一种简单快速检测汞离子的1,4-二硫苏糖醇膜修饰金平板电极

将1,4-二硫苏糖醇(DTT)自组装在100 nm厚的平整金膜表面, 形成DTT膜修饰金平板电极(GPE), 构建了一种新颖的简单、 快速测定汞离子的选择性电极分析方法. 通过电化学交流阻抗和循环伏安法探讨了该电极的响应原理, 即固定在Au表面的DTT通过另一端的巯基与汞离子发生强配位作用而吸附结合带正电荷的汞离子, 引起电极表面膜电位的变化, 从而选择性地识别汞离子. 实验结果表明, 该电极在pH=6.0的Tris-HCl缓冲溶液中对汞离子有良好的电位响应性能, 其线性范围为1.0×10^-8~1.0×10^-3 mol/L, 能斯特响应斜率为(29.62±0.2) mV/-pc(25 ℃), 检出限为5.1×10^-9 mol/L. 该汞离子检测电极的响应时间仅为20 s, 且有较好的重现性和稳定性. 通过测定各种离子的选择性系数, 发现Cu²⁺, Fe²⁺, Na⁺, K⁺, Mg²⁺, Ba²⁺, Ca²⁺, Zn²⁺, Sn²⁺, Pb²⁺, Ag⁺, Al³⁺, Fe³⁺, Ni²⁺, N\begin{array}{c}{O}_2^{-}\end{array}, I\begin{array}{c}{O}_3^{-}\end{array}, Br\begin{array}{c}{O}_3^{-}\end{array}和Cl\begin{array}{c}{O}_3^{-}\end{array}等离子不干扰该电极对汞离子的检测. 此外, 将该电极用于实际水样中微量汞离子含量的测定, 结果与双硫腙分光光度方法一致, 且回收率为98.20%~101.75%.

Simple and Rapid Determination of Mercury Ions Based on 1,4-Dithiothreitol Assembled Gold Plate Electrode†

A simply gold plate electrode(GPE) based on 1,4-dithiothreitol(DTT), which was self-assembled on a surface of flat gold film with a thickness of 100 nm, was developed to construct a novel selective electrode method for rapid detection of mercury ion. Through electrochemical impedance analysis and cyclic voltamme-tric method, the response mechanism of the electrode for selective recognition of Hg²⁺ was investigated, that the other terminal sulfhydryl group of DTT binding to Au surface can coordinate with Hg²⁺ due to their strong complexing interaction, resulting in change of membrane potential of the electrode surface. The proposed electrode possesses good potential performance responding to Hg²⁺ with a linear range of 1.0×10^-8—1.0×10^-3 mol/L, a Nernst slope of (29.62±0.2) mV/-pc(25 ℃), and a detection limit of 5.1×10^-9 mol/L in Tris-HCl buffer solution(pH=6.0). The electrode has short response time(20 s), good reproducibility and stability. No interference can be observed from most common ions like Cu²⁺, Fe²⁺, Na⁺, K⁺, Mg²⁺, Ba²⁺, Ca²⁺, Zn²⁺, Sn²⁺, Pb²⁺, Ag⁺, Al³⁺, Fe³⁺, Ni²⁺, N\begin{array}{c}{O}_2^{-}\end{array}, I\begin{array}{c}{O}_3^{-}\end{array}, Br\begin{array}{c}{O}_3^{-}\end{array} and Cl\begin{array}{c}{O}_3^{-}\end{array}. Compared with spectrophotometric method with dithizone, the proposed electrode can be well utilized to the determination of trace amount of Hg²⁺ in real water samples with a recovery rate of 98.20%—101.75%, showing promising application in environmental and other fields.