摘要:
研究了水杨醛缩硫脲合铜配合物[Cu(Ⅱ)-HBDT]为中性载体的PVC膜阴离子选择性电极.该电极对硫氰酸根离子呈现出优良的电位响应性能和选择性,并呈现反Hofmeister序列行为.其选择性序列从大到小为:SCN~-,ClO_4~-,Sal~-,I~-,NO_3~-,NO_2~-,Br~-,Cl~-,SO_3~(2-);Ac~-,SO_4~(2-),电极在Ph=5.0的磷酸盐缓冲体系中对SCN-在1.0×10~(-1)～1.0×10~(-5)mol/L浓度范围内呈近能斯特响应,斜率为-57.0 mV/dec,检测下限为4×10~(-6)mol/L.采用交流阻抗、紫外光谱分析技术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.将该电极用于环境废水中SCN~-的监测,获得满意的结果.
Abstract:
A new highly selective thiocyanate PVC membrane electrode with o-hydroxybenzaldehyde thiocarbohydrazone cupper(Ⅱ)as the neutral carrier is made,which displays an anti-Hofmeister selectivity sequence of SCN~-,ClO_4~-,Sal~-,I~-,NO_3~-,NO_2~-,Br~-,Cl~-,SO_3~(2-);Ac~-,SO_4~(2-).The electrode exhibits a near-Nernstian potential linear range to thiocyanate from 1.0×10~(-1) to 1.0×10~(-5)mol/L with a detection limit of 4×10~(-6) mol/L and a slope of -57.0 mV/dec in pH 5.0 of phosphorate buffer solution at 25 ℃.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 advantage of simplicity,fast response,fair stability and reproducibility and low detection limit.
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