Determination of acid dissociation constants of triazole fungicides by pressure assisted capillary electrophoresis

0446835 - ÚOCHB 2016 RIV NL eng J - Journal Article
Konášová, Renáta - Jaklová Dytrtová, Jana - Kašička, Václav
Determination of acid dissociation constants of triazole fungicides by pressure assisted capillary electrophoresis.
Journal of Chromatography A. Roč. 1408, Aug 21 (2015), s. 243-249. ISSN 0021-9673. E-ISSN 1873-3778
R&D Projects: GA ČR(CZ) GA13-17224S; GA ČR GP13-21409P
Institutional support: RVO:61388963
Keywords : triazole fungicides * acid dissociation constant * pK(a) * capillary electrophoresis * ionic mobility
Subject RIV: CB - Analytical Chemistry, Separation
Impact factor: 3.926, year: 2015

Pressure assisted capillary electrophoresis was applied to determination of acid dissociation constants (pK(a)) of six widely used triazole fungicides (cyproconazole, epoxiconazole, flusilazole, tebuconazole, penconazole and propiconazole) in aqueous medium. The pK(a) values were determined from the dependence of effective electrophoretic mobility of the triazole fungicides on p[H+] of the background electrolyte (BGE) using non-linear regression analysis. The p[H+] was used instead of pH to reflect the increased ionic strength of the strongly acidic BGEs (pH< 1.75) as compared to the BGEs at pH equal to or greater than 1.75. Prior to the pK(a) calculation, the measured effective electrophoretic mobilities were corrected to the reference temperature (25 degrees C) and constant ionic strength (25mM). The regression function was modified to allow the determination of pK(a) in the BGEs of varying ionic strength. The electrophoretic measurements showed that the above triazole fungicides are very weak bases their pK(a) values were found to be in the range 1.05-1.97 and were in a good agreement with the values calculated by SPARC online pK(a) calculator.
Permanent Link: http://hdl.handle.net/11104/0248799