聚氯乙烯膜碘离子选择电极在溴碘离子共存体系分析中的应用

APPLICATION OF PVC-MEMBRANE IODIDE ION SELECTIVE ELECTRODE TO THE ANALYSIS OF SYSTEM CO-EXISTING OF BROMIDE AND IODIDE IONS

介绍了聚氯乙烯膜碘离子选择电极（PVC-I^-ISE）的制备方法，电极对碘离子的能斯特响应斜率为59mV／pI，响应的线性范围为4．0×10^-5～1.0×10^-2mol·L^-1，检出限为1.6×10^-5mol·L^-1，低于用银ISE的检出限，电极的使用寿命为一个月以上。将制备的碘离子选择电极作为指示电极用于对溴、碘混合离子体系进行连续分别电位滴定，并与以银电极为指示电极的电位滴定方法进行了比较。结果表明用PVC-I^-ISE作指示电极，可在I^--Br^-共存的混合溶液中进行两离子的连续电位滴定，而用银-ISE时则不能。

Preparation of PVC-membrane iodide ISE was described and its electrochemical behaviors, especially its use as an indicator electrode in the potentiometric titration of iodide or bromide in the presence of each other, were studied. Linear response of this electrode was found in the range of 4.0× 10^-5 -1.0× 10^-2mol · L^-1 of iodide ion, with Nernst response slope of 59 mV/pI. Life of this I^- -ISE was found to be more than a month. As shown by experimental results, bromide and iodide in a mixture were titrated satisfactorily in succession by using the PVC-I^- -ISE, but it was impossible by using a silver-ISE. Besides, the detection limit of the PVC-I^- -ISE was found to be 1.6×10^-5mol · L^-1 of iodide, which is much lower than that of Ag-ISE.