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A Solid‐State Reference Electrode Based on a Self‐Referencing Pulstrode
Author(s) -
Gao Wenyue,
Zdrachek Elena,
Xie Xiaojiang,
Bakker Eric
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201912651
Subject(s) - electromotive force , reference electrode , valinomycin , chemistry , electrode , analytical chemistry (journal) , electrochemistry , potentiometric titration , iodide , ion , standard electrode potential , inorganic chemistry , electrical engineering , chromatography , organic chemistry , engineering
The design of solid‐state reference electrodes without a liquid junction is important to allow miniature and cost‐effective electrochemical sensors. To address this, a pulse control is proposed using an Ag/AgI element as reliable solid‐state reference electrode. It involves the local release of iodide by a cathodic current that is immediately followed by an electromotive force (EMF) measurement that serves as the reference potential. The recapture of iodide ions is achieved by potentiostatic control. This results in intermittent potential values that are reproducible to less than one millivolt (SD=0.27 mV, n =50). The ionic strength is shown to influence the activity coefficient of released iodide in accordance with the extended Debye–Hückel equation, resulting in a predictable change of the potential reading. The principle is applied to potentiometric potassium detection with a valinomycin‐based ion‐selective electrode (ISE), demonstrating a completely solid‐state sensor configuration.