Is there still a need for the antimony electrode 100 years after its introduction as a pH sensor?
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Is there still a need for the antimony electrode 100 years after its introduction as a pH sensor? Winfried Vonau 1 & Manfred Decker 1 & Ute Enseleit 1 & Frank Gerlach 1 Received: 28 April 2020 / Revised: 8 May 2020 / Accepted: 8 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Although the glass electrode, first mentioned in the literature over 100 years ago, is still the preferred analytical tool for determining hydrogen ion activity in aqueous media, there are a number of applications for other sensors that also measure pH. Even if they do not correspond to the measuring performance of the glass electrode in terms of, e.g., accuracy, reproducibility, and long-term stability, they open up the feasibility of using electrochemical sensors even where the operation with glass electrodes is not possible. This applies in particular to scenarios in which extreme and harsh environmental conditions prevail. Currently relevant here are, for example, measurements in geothermal plants or directly on arable land in agricultural production. In the present article, new electrochemical devices based on antimony electrodes are presented especially for these purposes; in addition, the use of the antimony electrode as a basic electrode for the CO2 determination according to the Severinghaus principle is reported on. Keywords pH value . Antimony electrode . Farmland sensor . Geothermal probe . Carbon dioxide determination
Introduction In the meantime, numerous measuring methods are available for determining the pH value. Compared to, e.g., optical and catalytic methods, the so-called electrometric analysis methods still dominate, which are used to determine the conventional pH value of the general interest in measuring chains with transfer. Components of the measuring chains, also called potentiometric sensors, are two halfcells known as electrochemical reference electrode and pH indicator electrode, by means of which the pH detection takes place via potential difference measurements. The most frequently used pH indicator electrode is the pH glass electrode [1] presented by Cremer for the first The article is dedicated to Professor Fritz Scholz on the occasion of his 65th birthday * Winfried Vonau [email protected] 1
Kurt-Schwabe-Institut für Mess- und Sensortechnik e.V. Meinsberg, Kurt-Schwabe-Straße 4, D- 04736 Waldheim, Germany
time, based on a series of preliminary works, which were systematically compiled in [2]. Several authors have subsequently dealt with theoretical explanations of its function, which are discussed in [3, 4]. Last but not least, it was found that a modification of the composition of special glasses suitable for pH measurement leads to electrochemical glass electrodes, e.g., for the detection of redox potentials [5]. Furthermore, various liquid or gel membrane electrodes, chemically sensitive field-effect transistors (CHEMFETs) based on microelectronic components and a series of metal/metal oxide electrodes, all together developed later [6],
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