Amperometric response of solid-contact ion-selective electrodes utilizing a two-compartment cell and a redox couple in solution
Amperometric response of solid-contact ion-selective electrodes utilizing a two-compartment cell and a redox couple in solution
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DOI：
10.1016/j.jelechem.2022.116683
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发表时间：
2022-08-26
影响因子：
4.5
通讯作者：
Niu, Li
中科院分区：
文献类型：
--
作者：
Han, Tingting;Song, Tao;Niu, Li
本文研究了一种离子选择性电极（ISE）的交替换能方法，即利用溶解在溶液中的Fe（CN）63-/4-氧化还原对的氧化/还原作用。采用两个隔室作为电化学电池，通过Ag/AgCl桥连接。具有还原的氧化石墨烯作为固体接触的K+选择性固体接触伊势（K+-SCISE）用作参比电极（RE），并放置在样品溶液隔室中。将充当工作电极（WE）的金电极和充当对电极（CE）的铂放置在具有含有Fe（CN）63-/4-氧化还原对的溶液的检测隔室中。随着初级离子（K+）浓度的变化，K+-SCISE的电势将相应地变化。由于WE和RE之间的电位通过使用恒电位仪保持恒定，所以一次离子K+的浓度的任何变化将导致来自Au WE表面处的Fe（CN）63-/4-氧化还原对的氧化/还原电流，从而导致电流在Au WE和Pt CE之间流动。Fe（CN）63-/4-氧化还原电对的氧化/还原的扩散限制电流在初级离子的一定浓度范围内与初级离子的活性的对数成线性比例。本文证明了Fe（CN）63-/4-氧化还原安培响应的可逆性和重现性。这种方法的一个独特之处是，电流信号可以通过增加WE的几何表面积来放大。Fe（CN）63-/4-氧化还原电对的安培响应高度依赖于所施加的起始电位。安培响应的灵敏度可以通过施加等于半峰电位（Ep/2）的电位来优化。此外，安培响应适用于测定K+离子浓度在这样一个要求苛刻的基质，如人血清。
An alternative transduction method for ion-selective electrodes (ISEs) is studied by utilizing oxidation/reduc-tion of a Fe(CN)63-/4-redox couple dissolved in solution. Two compartments are employed as electrochemical cell, connected by an Ag/AgCl bridge. A K+-selective solid-contact ISE (K+-SCISE) with reduced graphene oxide as solid contact works as reference electrode (RE) and is placed in the sample solution compartment. A gold electrode acting as working electrode (WE) and a platinum as counter electrode (CE) are placed in the detection compartment with a solution containing the Fe(CN)63-/4-redox couple. As the primary ion (K+) concentration changes, the potential of the K+-SCISE will change accordingly. Since the potential between WE and RE is kept constant by using a potentiostat, any change in the concentration of primary ion K+ will result in an oxidation/reduction current from the Fe(CN)63-/4-redox couple at the surface of the Au WE, causing a current flowing between the Au WE and Pt CE. The diffusion-limited current from oxidation/reduction of the Fe(CN)63-/4-redox couple is linearly proportional to the logarithm of the activity of the primary ion within a certain concentration range of the primary ion. The reversibility and reproducibility of the amperometric response from oxidation/reduction of Fe(CN)63-/4-is proven in this work. A unique feature of this method is that current signal can be enlarged by increasing the geometric surface area of the WE. The amperometric response of the Fe(CN)63-/4-redox couple is highly dependent on the applied starting potential. The sensitivity of the amperometric response can be optimized by applying a potential equal to the half-peak potential (Ep/2). Furthermore, the amperometric response is applied for determination of K+ ion concentration in such a demanding matrix as human blood serum.