Abstract
An unconventional structure was obtained by extraction of K+ ions with nitrobenzene solution of thiamine metatungstate. This shows that K+ penetration into the organic phase is not an exchange process. The solution of thiamine metatungstate in nitrobenzene acts as a spacial structure that entraps K+ ions in a molar ratio of 1 : 2. The absence of a chemical reaction between K+ and the metatungstic anion (proved experimentally) and the specificity of the interaction with K+, suggests that the formation of the structure potassium – thiamine metatungstate (KTM) could be controlled by dimensional criteria. The nitrobenzene solution of KTM shows a remarkable potentiometric selectivity for K+ compared with any other alkaline and alkaline earth cations. The potentiometric K+-selective electrode, based on KTM as ionophore, responds linearly in the range 3.8 × 10–5–1.0 × 10–1 mol/L, with a slope of 56 mV/ decade and a detection limit of 1.2 × 10–5 mol/L. The electrode maintained these response characteristics over a period of more than two months.
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Received: 12 May 1998 / Revised: 28 July 1998 / Accepted: 30 July 1998
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Doniga, E. Studies on the cationic selectivity of the potentiometric membrane containing thiamine metatungstate as ionophore. Fresenius J Anal Chem 363, 108–110 (1999). https://doi.org/10.1007/s002160051147
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DOI: https://doi.org/10.1007/s002160051147