汞配合物为载体的高灵敏PVC膜碘离子选择电极研究  

Studies of Highly Sensitive PVC Membrane Iodide Selective Electrode Based on Complexes of Mercury(Ⅱ) as Neutral Carriers

作　　者：柴雅琴[1] 许文菊[1] 袁若[1] 徐岚[1] 江璠[2] 

机构地区：[1]西南师范大学化学化工学院,重庆现代分析重点实验室重庆400715 [2]苏州科技学院化学系,苏州215011

出　　处：《化学学报》2004年第13期1226-1229,J003,共5页Acta Chimica Sinica

基　　金：教育部优秀青年教师资助计划 (No.教人司 2 0 0 2 40 );重庆市自然科学基金 (No.2 0 0 2 7477)资助项目

摘　　要：研究了基于四醋酸·双 ( 5 甲基 1,3 ,4 噻二唑 2 硫 ) -烷基合汞 (Ⅱ )配合物为中性载体的阴离子选择性电极 .这类电极对碘离子响应具有高灵敏和高选择性 ,并且呈现反Hofmeister序列行为 ,其选择性次序为 :I->SCN->ClO-4>Br->NO-3>Cl->AcO->SO2 -4.其中由四醋酸·双 ( 5 甲基 1,3 ,4 噻二唑 2 硫 ) -丁烷合汞 (Ⅱ)配合物为载体的电极在pH为 3 .0磷酸盐缓冲条件下对I-的线性响应范围为 4.0× 10 -8～ 1.0× 10 -2 mol/L ,检测限为 2 .0× 10 -8mol/L ,斜率为 -5 9.1mV/pcI- .通过紫外 -可见光谱和交流阻抗测试技术研究了电极的响应机理 .结果表明 ,配合物中心金属原子的结构以及载体本身的结构与电极的响应行为之间有非常密切的构效关系 .将该电极应用于嘉陵江水和缙云山泉水的测定 。A highly selective and sensitive iodide electrode based on the complexes of bis(5-methyl-1,3,4-thiadiazol-2-yl-thio)alkane mercury(Ⅱ) acetate as neutral carrier was developed, which displays an anti-Hofmeister selectivity sequence: I ->SCN ->ClO - 4>Br ->NO - 3>Cl ->AcO ->SO 2- 4. The electrode exhibits Nernstian potentiometric response to iodide with a linear range from 4.0×10 -8 to 1.0×10 -2 mol/L, a detection limit of 2.0×10 -8 mol/L and a slope of -59.1 mV/pc I - in pH 3.0 of phosphorate buffer solution at 20 ℃. The response mechanism was discussed in view of the a.c. impedance technique and the UV spectroscopy. The anti-Hofmeister behavior of the electrode results from the direct interaction between the central metal and the analyte ion and steric effect associated with the structure of the carrier. The electrode has the features of fast response, fair stability, reproducibility and low detection limit. The electrode was successfully applied to the determination of iodide in Jialing River and Spring in Jingyun Mountains with satisfactory results.

关 键 词：汞配合物 PVC膜 碘离子 阴离子选择性电极 中性载体 

分 类 号：O657.1[理学—分析化学]