Direct potentiometric information on total ionic concentrations.
Direct potentiometric information on total ionic concentrations.
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DOI：
10.1021/ac991092h
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发表时间：
2000-05
影响因子：
7.4
通讯作者：
A. Ceresa;E. Pretsch;E. Bakker
中科院分区：
文献类型：
--
作者：
A. Ceresa;E. Pretsch;E. Bakker
聚合物膜离子选择性电极表现出明显的super-Nernstian响应在低样品活动，如果内部的解决方案，诱导强大的零电流通量的初级离子向内室。这是由于膜附近的水边界层中的有限的离子通量。在不稳定的配合物的存在下，有效通量率增加，电动势取决于离子的总浓度。该概念用基于离子载体N，N-二环己基-N '，N'-双十八烷基-3-氧杂戊二酰胺（ETH 5234）的钙选择性电极进行实验说明，所述离子载体响应于总离子浓度或游离离子浓度。可以区分含有不同水平总钙的样本，但所有样本均用EDTA缓冲至相同的游离钙浓度5 × 10（-8）M。
Polymeric membrane ion-selective electrodes exhibit an apparently super-Nernstian response at low sample activities if inner solutions are used that induce strong zero-current fluxes of primary ions toward the inner compartment. This is due to the limited ion fluxes in the aqueous boundary layer near the membrane. In the presence of labile complexes, the effective flux rate is increased and the emf depends on the total concentration of the ions. The concept is illustrated experimentally with calcium-selective electrodes based on the ionophore N,N-dicyclohexyl-N',N'-dioctadecyl-3-oxapentanediamide (ETH 5234) that either respond to total or free ion concentrations. Samples can be distinguished that contain varying levels of total calcium but are all buffered with EDTA to the same free calcium concentration of 5 x 10(-8) M.