Keresten Valentina, Solovyeva Elena, Mikhelson Konstantin
Chemistry Institute, Saint Petersburg State University, 26 Universitetsky Prospect, 198504 Saint Petersburg, Russia.
Membranes (Basel). 2021 May 7;11(5):344. doi: 10.3390/membranes11050344.
The dependence of the bulk resistance of membranes of ionophore-based ion-selective electrodes (ISEs) on the composition of mixed electrolyte solutions, within the range of the Nernstian potentiometric response, is studied by chronopotentiometric and impedance measurements. In parallel to the resistance, water uptake by the membranes is also studied gravimetrically. The similarity of the respective curves is registered and explained in terms of heterogeneity of the membranes due to the presence of dispersed aqueous phase (water droplets). It is concluded that the electrochemical equilibrium is established between aqueous solution and the continuous organic phase, while the resistance refers to the membrane as whole, and water droplets hamper the charge transfer across the membranes. In this way, it is explained why the membrane bulk resistance is not constant within the range of the Nernstian potentiometric response of ISEs.
通过计时电位法和阻抗测量，研究了基于离子载体的离子选择性电极（ISE）膜的体电阻在能斯特电位响应范围内对混合电解质溶液组成的依赖性。与电阻测量并行，还通过重量法研究了膜的水吸收情况。记录了各自曲线的相似性，并根据由于存在分散水相（水滴）导致的膜的不均匀性进行了解释。得出的结论是，在水溶液和连续有机相之间建立了电化学平衡，而电阻是指整个膜的电阻，水滴阻碍了电荷在膜中的转移。以此方式解释了为什么ISE的能斯特电位响应范围内膜的体电阻不是恒定的。
