Selectivity of potentiometric ion sensors
Selectivity of potentiometric ion sensors
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DOI：
10.1021/ac991146n
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发表时间：
2000-03-15
影响因子：
7.4
通讯作者：
Bühlmann, P
中科院分区：
文献类型：
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作者：
Bakker, E;Pretsch, E;Bühlmann, P
溶剂聚合物膜离子选择性电极（ISE）的选择性与样品和电极膜之间的界面处的平衡定量相关。然而，只有正确确定的选择性系数才能准确预测真实样品的伊势响应。此外，它们还需要优化离子载体结构和膜组成。最适合这种目的的是已经在20世纪60年代定义的电位选择性系数。本文简要回顾了选择性系数的基本关系，并着重讨论了选择性系数测定中可能存在的偏差。传统的选择性系数测定方法（分别溶液法、固定干扰法）仍沿用IUPAC于1976年提出的方法。然而，需要采取一些预防措施才能获得有意义的数据。例如，当对弱干扰离子的响应也受到从膜中浸出的初级离子的影响时，就会出现误差。当干扰剂是高度优选的并且电极显示反干扰时，也可能获得错误的选择性系数。最近的进展表明，如何避免这种陷阱。一个详细的配方，以确定正确的电位选择性系数不受这种偏见。
Selectivities of solvent polymeric membrane ion-selective electrodes (ISEs) are quantitatively related to equilibria at the interface between the sample and the electrode membrane. However, only correctly determined selectivity coefficients allow accurate predictions of ISE responses to real-world samples. Moreover, they are also required for the optimization of ionophore structures and membrane compositions. Best suited for such purposes are potentiometric selectivity coefficients as defined already in the 1960s. This paper briefly reviews the basic relationships and focuses on possible biases in the determination of selectivity coefficients. The traditional methods to determine selectivity coefficients (separate solution method, fixed interference method) are still the same as those originally proposed by IUPAC in 1976. However, several precautions are needed to obtain meaningful data. For example, errors arise when the response to a weakly interfering ion is also influenced by the primary ion leaching from the membrane. Wrong selectivity coefficients may be also obtained when the interfering agent is highly preferred and the electrode shows counterion interference. Recent advances show how such pitfalls can be avoided. A detailed recipe to determine correct potentiometric selectivity coefficients unaffected by such biases is presented.