新型高选择性硫氰酸根离子电极的研究

Study on novel highly selective thiocyanate electrode

首次研制了基于二苯甲酮缩氨基硫脲合铜(Ⅱ)金属配合物[Cu(Ⅱ)-BBKT]为中性载体的阴离子选择性电极。该电极对硫氰酸根(SCN^-)具有优良的电位响应性能,并呈现出反 Hofmeister 选择性行为,其选择性次序为:SCN^->I^-≈Sal^->ClO_4^->Br^->NO_3^->NO_2^->F^->SO_3^(2-)>SO_4^(2-)。在 pH5.0的磷酸盐缓冲体系中,电极电位呈现近能斯特响应,线性响应范围为8.0×10^(-6)～1.0×10^(-1)mol/L,斜率为-55.2mV/dec(20℃),检测下限是4.5×10^(-6)mol/L。采用交流阻抗技术和紫外可见光谱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。并将该电极用于实验室废水硫氰酸根检测,其结果令人满意。

A novel highly thiocyanate-selective PVC membrane electrode based on N, N'-bis-(biphenyl ketone) -thiosemicarhazone copper(Ⅱ) complex as neutral carrier is described,Which displays a preferential potentiometrie response to thiocyanate and an anti -Hofmeister selectivity sequence in following order:SCN^->Ⅰ^-≈Sal^-> ClO_4^->Br^->NO_3^->NO_2^->F^->SO_3^(2-)>SO_4^(2-).The electrode exhibits near Nernstian potential linear range of 8.0×10^(-6)～1.0×10^(-1) mol/L with a detection limit 4.5×10^(-6) mol/L and a slope of-55.2 mV/decade in pH 5.0 of phosphorate buffer solution at 20℃.The response mechanism is discussed in view of the A.C.impedance technique and the UV spectroscopy technique.These deviations result 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 advantages of simplicity,fast response,fair stability reproducibility and low detection limit.The electrode can be applied to thio- cyanate of waster water analysis and the result is fair agreement with that given by HPLC method.