Determination of pKa values of some hydroxylated benzoic acids in methanol-water binary mixtures by LC methodology and potentiometry |
| |
Authors: | F.Z. Erdemgil,N. ?anli,J. Barbosa,J.L. Beltrá n |
| |
Affiliation: | a Anadolu University, BIBAM, 26470 Eski?ehir, Turkey b Department of Chemistry, Faculty of Science and Literature, Süleyman Demirel, University, 32260 Isparta, Turkey c Department of Analytical Chemistry, Barcelona University, Diagonal 647, 08028 Barcelona, Spain |
| |
Abstract: | An accurate estimation of pKa values in methanol-water binary mixtures is very important for several separation techniques such as liquid chromatography and capillary electrophoresis that use these solvent mixtures. In this study, the pKa values of 11 polyphenolic acids have been determined in methanol-water binary mixtures (10%, 20% and 30% (v/v)) by potentiometry, liquid chromatography (LC) and LC-DAD methodology.The results show a similar trend for the pKa values of all the studied compounds, as they increase with increasing concentration of organic modifier, which allows a linear relationship between pKa values and mole fraction of methanol to be obtained. The pKa values obtained in aqueous medium have been compared with those given in the literature, and also with the values predicted by the SPARC on-line pKa calculator. The data obtained have been used to test the feasibility of an estimation of dissociation constants in a methanol-water medium from the relationship between pKa values and the organic cosolvent fraction in the mixtures. |
| |
Keywords: | Dissociation constants Polyphenolic acids Methanol-water mixtures Liquid chromatography |
本文献已被 ScienceDirect 等数据库收录! |
|