Lowering the detection limit of solvent polymeric ion-selective membrane electrodes. 2. Influence of composition of sample and internal electrolyte solution
Lowering the detection limit of solvent polymeric ion-selective membrane electrodes. 2. Influence of composition of sample and internal electrolyte solution
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DOI：
10.1021/ac9809332
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发表时间：
1999-03-15
影响因子：
7.4
通讯作者：
Pretsch, E
中科院分区：
文献类型：
--
作者：
Sokalski, T;Ceresa, A;Pretsch, E
研究了内电解液组成对Pb2+和Ca2+选择性膜电极响应的影响。结果表明，通过在膜中产生离子梯度，导致初级离子流向内参比电解质溶液，从而提高了检测下限。如果离子通量太强，可能会导致膜表面的分析物耗尽，结果是明显的超能斯特反应。这种电极不足以测量低分析物的活性，但可以用来确定无偏的选择性因子。结果用稳态模型来解释，该模型描述了离子交换和共萃取过程产生的浓度梯度对膜两侧的影响。
The influence of the composition of the internal electrolyte solution on the response of Pb2+- and Ca2+-selective membrane electrodes is investigated. It is shown that the lower detection limit is improved by generating, in the membrane, ionic gradients that lead to a flux of primary ions toward the inner reference electrolyte solution. If the ion flux is too strong, it may cause analyte depletion at the membrane surface and, as a consequence, apparent super-Nernstian response. Such electrodes are not adequate to measure low analyte activities but can be used to determine unbiased selectivity factors. The results are interpreted in terms of a steady-state model, introduced in the companion paper, that describes the influence of concentration gradients generated by ion-exchange and coextraction processes on both sides of the membrane.