Solid‐contact Acetate‐selective Electrode Based on a 1,3‐bis(carbazolyl)urea‐ionophore

• Published in: Electroanalysis (New York, N.Y.) N.Y.), 2019-06, Vol.31 (6), p.1061-1066
• Main Authors: Martin, Kerli, Kadam, Sandip A., Mattinen, Ulriika, Bobacka, Johan, Leito, Ivo
• Format: Article
• Language: English
• Subjects: Acetate recognition; Conducting materials; Ionophores; Poly(3,4-ethylenedioxythiophene); Solid-contact anion-selective electrode
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.201800790

The construction and study of solid‐contact acetate‐selective electrodes is described using a 1,3‐bis(carbazolyl)urea derivative as a neutral hydrogen‐bonding ionophore and poly(3,4‐ethylenedioxythiophene) as the solid contact. It was shown recently that this ionophore binds acetate (logKass=4.98) that is used as primary ion in this study. The electrodes show linearity over the activity range of 10−4.50–10−1.10 with a sub‐Nernstian slope of −51.3 mV per decade and a detection limit of 10−5.00. The anion‐selectivity pattern of these electrodes deviates markedly from the Hofmeister pattern. When adding ionophore to the membrane the logarithm of the selectivity coefficient (logK) for SCN− decreased from 6.5 to 1.2, logK for I− decreased from 5.7 to 0.9, logK for NO3− decreased from 4.3 to 0.6 and logK for Br− decreased from 3.3 to 0.1. The selectivity coefficients of hydrophilic anions such as Cl−, F−, HPO42−, and SO42− are significantly lower than in case of the ionophore‐free membrane. It was discovered that the constructed electrodes are also relatively selective to bicarbonate. This work is an important step towards the further development of solid‐contact anion‐selective electrodes.