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Separation of rotamers of 5-nitrosopyrimidines by capillary electrophoresis
Štěpánová, Sille ; Procházková, Eliška ; Čechová, Lucie ; Žurek, Jiří ; Janeba, Zlatko ; Dračínský, Martin ; Kašička, Václav
A new capillary electrophoresis (CE) method was developed for the separation of a new type of stereoisomers - rotamers of polysubstituted 5-nitrosopyrimidine derivatives. Partial separation of some rotamers was obtained in sodium borate, pH 9.3, or in Tris-phosphate, pH 2.2, background electrolytes (BGEs) free of cyclodextrins (CDs). However, the best, baseline separations of the rotamers of 5-nitrosopyrimidines were achieved in sodium borate BGE, pH 9.3, containing 20 mg/mL beta-CD as stereoselector, or in Tris-phosphate BGE, pH 2.2, with carboxymethyl-beta-CD as stereoselector.
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Determination of stability constants of antamanide complexes with sodium and potassium ions by affinity capillary electrophoresis
Pangavhane, Sachin ; Böhm, S. ; Makrlík, E. ; Ruzza, P. ; Kašička, Václav
Affinity capillary electrophoresis (ACE) was applied for quantitative investigation of the interactions between important biomolecule, cyclic decapeptide antamanide (AA), cycl[-Val(1)-Pro(2)-Pro(3)-Ala(4)-Phe(5)-Phe(6)-Pro(7)-Pro(8)-Phe(9)-Phe(10)-], and sodium and potassium cations in methanol. Apparent stability constants of AA complexes with these alkali metal ions were determined from the dependence of effective mobility of AA on the concentration of these ions in the background electrolyte by the non-linear regression analysis. The AA complexes with Na+ and K+ ions were found to be relatively weak, with the apparent stability constants 343 L/mol and 35 L/mol, respectively.
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Determination of Bitrex in conifer needles using capillary electrophoresis
Jaklová Dytrtová, Jana ; Jakl, M. ; Konášová, Renáta ; Kašička, Václav
Two extraction procedures have been developed for the sample preparation regarding the determination of Bitrex (Denatonium benzoate) on the surface of conifer needles (1) and in the biomass of the chopped conifer needles (2). The content of the Bitrex in the extracts was determined by capillary electrophoresis with UV-absorption photometric detection. The recovery of Bitrex from the needle surface is 90%, however the procedure designed for determination of Bitrex from needles is not sufficient, because the recovery is only 30 %.
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Affinity capillary electrophoresis applied to chiral separations of diquats and to determination of the stability constants of their complexes with sulfated cyclodextrins
Kašička, Václav ; Bílek, Jan ; Koval, Dušan ; Sázelová, Petra ; Talele, Harish Ramesh ; Severa, Lukáš ; Reyes Gutierrez, Paul Eduardo ; Teplý, Filip
Affinity capillary electrophoresis (ACE) using an aqueous 22/35 mM sodium/phosphate buffer, pH 2.5, as the background electrolyte (BGE), and 6 mM randomly highly sulfated alpha-, beta- and gamma-cyclodextrins (CDs) as chiral selectors has been successfully applied for separation of (P)- and (M)-enantiomers of a series of eleven new diquats (DQs) and for estimation of the strength of their complexes with the above CDs. The apparent stability constants of the DQs-CDs complexes were determined from the simultaneous ACE measurements of the dependence of effective electrophoretic mobilities of (P)- and (M)-enantiomers of DQs on the concentrations of CDs in the BGE by nonlinear regression analysis. The DQs enantiomers formed strong complexes with all three types of CDs with the apparent stability constants in the range (7.80 547.4) × 103 L/mol.
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