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Solid‐contact Acetate‐selective Electrode Based on a 1,3‐bis(carbazolyl)urea‐ionophore
Author(s) -
Martin Kerli,
Kadam Sandip A.,
Mattinen Ulriika,
Bobacka Johan,
Leito Ivo
Publication year - 2019
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201800790
Subject(s) - ionophore , selectivity , chemistry , electrode , urea , membrane , inorganic chemistry , potentiometric titration , ion selective electrode , ion , nuclear chemistry , analytical chemistry (journal) , chromatography , organic chemistry , biochemistry , catalysis
Abstract 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 (log K ass =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 (log K ) for SCN − decreased from 6.5 to 1.2, log K for I − decreased from 5.7 to 0.9, log K for NO 3 − decreased from 4.3 to 0.6 and log K for Br − decreased from 3.3 to 0.1. The selectivity coefficients of hydrophilic anions such as Cl − , F − , HPO 4 2− , and SO 4 2− 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.