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Článek

Determination of thermodynamic acidity constants and limiting ionic mobilities of weak electrolytes by capillary electrophoresis using a new free software AnglerFish

Malý, Michal
Autor Malý, Michal Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic
Boublík, Milan
Autor Boublík, Milan Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic
Pocrnić, Marijana
Autor Pocrnić, Marijana Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia
Ansorge, Martin
Autor Ansorge, Martin Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic
Lorinčíková, Kateřina
Autor Lorinčíková, Kateřina Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic
Svobodová, Jana
Autor Svobodová, Jana Agilent Technologies Deutschland GmbH & Co. KG, Liquid Phase Separations Division, Waldbronn, Germany
Hruška, Vlastimil
Autor Hruška, Vlastimil Agilent Technologies Deutschland GmbH & Co. KG, Liquid Phase Separations Division, Waldbronn, Germany
Dubský, Pavel
Autor Dubský, Pavel Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic
Gaš, Bohuslav
Autor Gaš, Bohuslav Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic

Electrophoresis. 2020 ; 41 (7-8) : 493-501. [pub] 20191106

ISSN 1522-2683
Medvik
Zdroj

Thermodynamic acidity constants (acid or acid-base dissociation constants, sometimes called also as ionization constants) and limiting ionic mobilities (both of them at defined temperature, usually 25°C) are the fundamental physicochemical characteristics of a weak electrolyte, that is, weak acid or weak base or ampholyte. We introduce a novel method for determining the data of a weak electrolyte by the nonlinear regression of effective electrophoretic mobility versus buffer composition dependence when measured in a set of BGEs with various pH. To correct the experimental data for zero ionic strength we use the extended Debye-Hückel model and Onsager-Fuoss law with no simplifications. Contrary to contemporary approaches, the nonlinear regression is performed on limiting mobility data calculated by PeakMaster's correction engine, not on the raw experimental mobility data. Therefore, there is no requirement to perform all measurements at a constant ionic strength of the set of BGEs. We devised the computer program AnglerFish that performs the necessary calculations in a user-friendly fashion. All thermodynamic pKa values and limiting electrophoretic mobilities for arbitrarily charged substances having any number of ionic forms are calculated by one fit. The user input consists of the buffer composition of the set of BGEs and experimentally measured effective mobilities of the inspected weak electrolyte.