苯甲醛缩氨基脲铜(Ⅱ)配合物为载体的高选择性硫氰酸根离子电极的研究

Study on Highly Selective Thiocyanate Electrode Based on Benzaldehyde Semicarbazone Copper(Ⅱ) Complex as Neutral Carriers

首次研究以苯甲醛缩氨基脲铜 (Ⅱ ) [Cu(Ⅱ ) BASA]为中性载体的PVC膜电极 ,该电极对硫氰酸根离子 (SCN-)具有优良的电位响应特性并呈现出反Hofmeister选择性行为 ,其选择性次序为 :SCN->ClO-4>I->Sal->Br->NO-3 >Cl->NO-2 >SO2 -3 >SO2 -4>H2 PO-4.电极在pH 6 0的磷酸盐缓冲体系中 ,对SCN-在 1 0× 10 -1～ 8 0× 10 -6mol/L浓度范围内呈近能斯特响应 ,斜率为 5 6 0mV/pSCN-(2 8℃ ) ,检测下限为 3 0× 10 -6mol/L .采用交流阻抗技术和紫外可见光谱技术初步研究了阴离子与载体的作用机理 ,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 .该电极具有响应快、重现性好、检测限低、制备简单等优点 .将电极初步应用于实际样品废水分析 ,结果与HPLC法一致 .

A new highly selective thiocyanate electrode based on benzaldehyde semicarbazone copper(Ⅱ) complex [Cu(Ⅱ)-BASA] as neutral carrier is developed, which displays an anti-Hofmeister selectivity sequence: SCN ->ClO -_4>I ->Sal ->Br ->NO -_3>Cl ->NO -_2>SO 2- _3>SO 2- _4>H_2PO -_4. The electrode exhibits Nernstian potential linear range to thiocyanate from 1.0×10 -1 to 8.0×10 -6 mol/L with a detection limit 3.0×10 -6 mol/L and a slope of 56.0 mV/pSCN - in phosphate buffer solution (pH 6.0) at 28 ℃. The response mechanism is discussed in view of a.c. impedance technique and UV spectroscopy technique. These deviations result from the direct interaction between the central metal and the analyte ions and the steric effect associated with the structure of the carrier. The electrode has the advantages of simplicity, fast response, fair stability and reproducibility and low detection limit. The electrode can be applied to waste water analysis and the result obtained exhibits fair agreement with the result given by HPLC methods.