The paper extends applicability of the internal standard method published in 2009 (Fuguet E. et al., J. Chromatogr. A 2009, 1216(17), 3646). Although the original capillary zone electrophoresis method was suggested to determine thermodynamic acidity constants of compounds sparingly soluble in aqueous solutions by carrying out only runs at two different pH values (i.e., without the need to perform many experiments over the appropriate pH range including the form of a low-ionized analyte), we proved that the approach also virtually overcomes any interactions of the analyte in mixed solvents, so that the experiments can be carried out in a methanol-water buffer where the solubility is much better. Applicability of the extended method is illustrated on six selected β-blockers.

Department of Chemical Drugs Faculty of Pharmacy Masaryk University Palackého 1946 1 CZ 612 00 Brno Czech Republic

Department of Experimental Phycology and Ecotoxicology Institute of Botany of the Czech Academy of Sciences Research Division Brno Lidická 25 27 CZ 602 00 Brno Czech Republic

Zobrazit více v PubMed

Gluck S. J.; Cleveland J. A. Investigation of experimental approaches to the determination of pKa values by capillary electrophoresis. J. Chromatogr. A 1994, 680, 49–56. 10.1016/0021-9673(94)80051-0. DOI

Poole S. K.; Patel S.; Dehring K.; Workman H.; Poole C. F. Determination of acid dissociation constants by capillary electrophoresis. J. Chromatogr. A 2004, 1037, 445–454. 10.1016/j.chroma.2004.02.087. PubMed DOI

Nowak P.; Woźniakiewicz M.; Kościelniak P. Application of capillary electrophoresis in determination of acid dissociation constant values. J. Chromatogr. A 2015, 1377, 1–12. 10.1016/j.chroma.2014.12.032. PubMed DOI

Ishihama Y.; Oda Y.; Asakawa N. Microscale Determination of Dissociation Constants of Multivalent Pharmaceuticals by Capillary Electrophoresis. J. Pharm. Sci. 1994, 83, 1500–1507. 10.1002/jps.2600831025. PubMed DOI

Malý M.; Boublík M.; Pocrnić M.; Ansorge M.; Lorinčíková K.; Svobodová J.; Hruška V.; Dubský P.; Gaš B. Determination of thermodynamic acidity constants and limiting ionic mobilities of weak electrolytes by capillary electrophoresis using a new free software AnglerFish. Electrophoresis 2020, 41, 493–501. Article10.1002/elps.201900283. PubMed DOI

de Nogales V.; Ruiz R.; Rosés M.; Ràfols C.; Bosch E. Background electrolytes in 50% methanol/water for the determination of acidity constants of basic drugs by capillary zone electrophoresis. J. Chromatogr. A 2006, 1123, 113–120. 10.1016/j.chroma.2006.05.008. PubMed DOI

Rosés M.; Bosch E. Influence of mobile phase acid-base equilibria on the chromatographic behaviour of protolytic compounds. J. Chromatogr. A 2002, 982, 1–30. 10.1016/S0021-9673(02)01444-9. PubMed DOI

Avdeef A.; Comer J. E. A.; Thomson S. J. pH-Metric log P. 3. Glass electrode calibration in methanol-water, applied to pKa determination of water-insoluble substances. Anal. Chem. 1993, 65, 42–49. 10.1021/ac00049a010. DOI

Rived F.; Canals I.; Bosch E.; Rosés M. Acidity in methanol-water. Anal. Chim. Acta 2001, 439, 315–333. 10.1016/S0003-2670(01)01046-7. DOI

Ehala S.; Míšek J.; Stará I. G.; Starý I.; Kašička V. Determination of acid-base dissociation constants of azahelicenes by capillary zone electrophoresis. J. Sep. Sci. 2008, 31, 2686–2693. 10.1002/jssc.200800227. PubMed DOI

Fuguet E.; Ràfols C.; Bosch E.; Rosés M. Fast high-throughput method for the determination of acidity constants by capillary electrophoresis. J. Chromatogr. A 2009, 1216, 3646–3651. 10.1016/j.chroma.2008.12.090. PubMed DOI

Cabot J. M.; Fuguet E.; Ràfols C.; Rosés M. Fast high-throughput method for the determination of acidity constants by capillary electrophoresis. II. Acidic internal standards. J. Chromatogr. A 2010, 1217, 8340–8345. 10.1016/j.chroma.2010.10.060. PubMed DOI

Fuguet E.; Ràfols C.; Rosés M. A fast high throughput method for the determination of acidity constants by capillary electrophoresis. 3. Basic internal standards. J. Chromatogr. A 2011, 1218, 3928–3934. 10.1016/j.chroma.2011.04.054. PubMed DOI

Cabot J. M.; Fuguet E.; Ràfols C.; Rosés M. Determination of acidity constants by the capillary electrophoresis internal standard method. IV. Polyprotic compounds. J. Chromatogr. A 2013, 1279, 108–116. 10.1016/j.chroma.2013.01.018. PubMed DOI

Cabot J. M.; Fuguet E.; Rosés M. Determination of acidity constants of sparingly soluble drugs in aqueous solution by the internal standard capillary electrophoresis method. Electrophoresis 2014, 35, 3564–3569. 10.1002/elps.201400353. PubMed DOI

Gravador R. S.; Fuguet E.; Ràfols C.; Rosés M. Temperature variation effects on the determination of acidity constants through the internal standard-capillary electrophoresis method. Electrophoresis 2013, 34, 1203–1211. 10.1002/elps.201200584. PubMed DOI

Cabot J. M.; Fuguet E.; Rosés M. Internal Standard Capillary Electrophoresis as a High-Throughput Method for pKa Determination in Drug Discovery and Development. ACS Comb. Sci. 2014, 16, 518–525. 10.1021/co500059p. PubMed DOI

Cabot J. M.; Fuguet E.; Rosés M.; Smejkal P.; Breadmore M. C. Novel Instrument for Automated pKa Determination by Internal Standard Capillary Electrophoresis. Anal. Chem. 2015, 87, 6165–6172. 10.1021/acs.analchem.5b00845. PubMed DOI

Good N. E.; Izawa S.. [3] Hydrogen ion buffers. In Methods in Enzymology; Academic Press, 1972; Vol. 24, pp 53–68. PubMed

Gebauer P.; Pantůiková P.; Bocek P. Capillary zone electrophoresis in phosphate buffer--known or unknown?. J. Chromatogr. A 2000, 894, 89–93. 10.1016/S0021-9673(00)00707-X. PubMed DOI

Fuguet E.; Reta M.; Gibert C.; Rosés M.; Bosch E.; Ràfols C. Critical evaluation of buffering solutions for pKadetermination by capillary electrophoresis. Electrophoresis 2008, 29, 2841–2851. 10.1002/elps.200700869. PubMed DOI

Šlampová A.; Křivánková L.; Gebauer P.; Boček P. Standard systems for measurement of pKs and ionic mobilities. J. Chromatogr. A 2008, 1213, 25–30. 10.1016/j.chroma.2008.08.101. PubMed DOI

Šlampová A.; Křivánková L.; Gebauer P.; Boček P. Standard systems for measurement of pK values and ionic mobilities. J. Chromatogr. A 2009, 1216, 3637–3641. 10.1016/j.chroma.2009.01.018. PubMed DOI

Williams B. A.; Vigh G. Effect of the initial potential ramp on the accuracy of electrophoretic mobilities in capillary electrophoresis. Anal. Chem. 1995, 67, 3079–3081. 10.1021/ac00113a051. DOI

Brittain H. G.Profiles of Drug Substances, Excipients and Related Methodology: Critical Compilation of pKa Values for Pharmaceutical Substances; Elsevier, 2007. PubMed

Shalaeva M.; Kenseth J.; Lombardo F.; Bastin A. Measurement of Dissociation Constants (pKa Values) of Organic Compounds by Multiplexed Capillary Electrophoresis Using Aqueous and Cosolvent Buffers**Advanced Analytical Technologies, Inc. (Formerly CombiSep), 2711 South Loop Drive, Suite 4200, Ames, IA 50010. J. Pharm. Sci. 2008, 97, 2581–2606. 10.1002/jps.21287. PubMed DOI