Hambly Bradley, Guzinski Marcin, Pendley Bradford, Lindner Ernő
Department of Biomedical Engineering, University of Memphis, Memphis, Tennessee 38152, United States.
Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States.
ACS Sens. 2020 Jul 24;5(7):2146-2154. doi: 10.1021/acssensors.0c00774. Epub 2020 Jul 7.
The theoretical models for ISEs almost exclusively assume thermodynamic equilibrium at the membrane/solution-phase boundary. In this report, we present a new, congruent model which combines first-order reaction kinetics of ion-exchange at the phase boundary and diffusional mass transport in the adjoining phases in the continuity equation. The influence of the rate constant in the new kinetic model has significant impact on the predicted transients corresponding to instantaneous change in the sample solution composition. The simulated transients generated with the new model coincide with the transients recorded in common potentiometric experiments, e.g., with transients recorded upon step change in the primary or interfering ion concentrations. The simulated transients also align well with previously published transients representing special cases of potentiometry (e.g., super-Nernstian response, non-Nernstian responses in the presence of highly interfering ions). The implementation of the kinetic model for simulating the transients in the water layer test also resulted in a better agreement with the experiments compared to the previous models.
离子选择性电极（ISEs）的理论模型几乎都假定在膜/溶液相边界处存在热力学平衡。在本报告中，我们提出了一种新的、一致的模型，该模型将相边界处离子交换的一级反应动力学与连续性方程中相邻相中扩散传质相结合。新动力学模型中的速率常数对与样品溶液组成瞬时变化相对应的预测瞬态有显著影响。用新模型生成的模拟瞬态与普通电位实验中记录的瞬态一致，例如与初级离子或干扰离子浓度阶跃变化时记录的瞬态一致。模拟瞬态也与先前发表的代表电位法特殊情况的瞬态（例如，超能斯特响应、存在高干扰离子时的非能斯特响应）吻合良好。与先前的模型相比，在水层测试中用于模拟瞬态的动力学模型的实施也与实验结果取得了更好的一致性。
