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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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Software Tools for Optimization of Background Electrolytes in Electrophoresis
Hruška, Vlastimil ; Gaš, Bohuslav (advisor) ; Gebauer, Petr (referee) ; Kašička, Václav (referee)
7. Results The aim of my PhD. thesis was development of software tools for optimization of background electÍolytes in electrophoresis, study of system peak and general theory of electromigration. During my study I cooperated on the programming of the program PeakMaster 5 and I implemented theory of amplitudes to it (PeakMaster 5.2). The main subject of my work was development of the program Simul 5. During my study I added several new features, which significantly improved is capabilities and fields of applications. Both prcgrams are often used at many universities all over the world. Especially, program PeakMaster is very popular among wide range of users thank to its fast calculation of pH with very good ionic strength correction. Funher, I cooperated on finding of some reď systems, whose prediction was based on linearization of electromigration problem and properties of system peal6 such as discovery of oscillating electrolytes, systems without stationary system zones (without regulation functions) or urilization of system peaks in micellar electrophoresis for determination of CMC of micelles. . .!r ! Li-a.. --,;ared in the following qhaBlers.
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Dynamic Enantioseparation in Capillary Zone Electrophoresis
Dubský, Pavel ; Gaš, Bohuslav (advisor) ; Kašička, Václav (referee) ; Gebauer, Petr (referee)
12 4 CONCLUSION In the framework of my Ph.D. study, software EvalChir was developed for evaluation of elution profiles from dynamic enantioseparation. Further our previously developed simulation software SimulChir was extended by an iterative algorithm to be able to fit the experimental peak profiles by simulated ones and to find out the apparent rate constant of interconversion. Both the programs form complex solution for fast and easy evaluation of data obtained from dynamic enantioseparation techniques. A new method for determination of all four rate constants of interconversion involved in the true scheme (Figure 1A) was designed. In this way, the apparent thermodynamics is resolved back to the true one and an influence of a CS on the rate of interconversion can newly be studied. We verified this technique experimentally. A multi-CS enantioseparative system was described considering interaction of a chiral analyte with any arbitrary mixture of CSs. The model indicates that any multi-CS system may be formally treated as if only one CS was present there with some overall distribution constant, overall limit mobility and overall rate constant of interconversion of an enantiomer with respect to the mixture of CSs as a whole. The exact composition of the mixture even does not need to be known at all. On the...
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Chiral separation of diquats and determination of stability constants of their complexes with cyclodextrins by capillary electrophoresis
Bílek, Jan ; Kašička, Václav (advisor) ; Jelínek, Ivan (referee)
Capillary zone electrophoresis was used for chiral separation of eleven diquat derivatives. These N-heteroaromatic dications containing structural motif of 2,2'-bipyridine have recently been studied for their interesting electrochemical properties as well as for the axial chirality of their molecules. The combination of these properties could potencially lead to interesting applications in the future. For enantioseparation of diquats (DQ) commercially available randomly sulfated α-, β-, and γ-cyclodextrins with high degree of substitution were used. A succesfull chiral separation was achieved using all of the three sulfated cyclodextrins as chiral selectors (CS). Baseline enantioseparation was achieved for 82 %, 91 % respectively 100 % of the analyzed DQ in the presence of HS-α-CD, HS-β-CD, HS-γ-CD respectively. The highest separation efficiency and resolution were obtained in the backround electrolyte containing 22 mmol/L NaOH, 35 mmol/L H3PO4 (pH2,5) and 6 mmol/L HS-β-CD. Using three available nonracemic DQ an identification of the particular M- and P-enantiomers was done for the three corresponding DQ structures. Apparent stabillity constants of complexes of the DQ derivatives with above mentioned cyclodextrins as CS were determined by means of capillary affinity electrophoresis. The stability...
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Influence of the interacting constituent of the background electrolyte on electrophoretic separation
Müllerová, Ludmila ; Dubský, Pavel (advisor) ; Kašička, Václav (referee) ; Petr, Jan (referee)
Capillary electrophoresis is a widely used separation method of analytical chemistry. Addition of a selector into the background electrolyte extends its applicability to separation of enantiomers or of compounds of similar physicochemical properties. In analytical practice, mixtures of selectors are also commonly used - either prepared intentionally to achieve better separation or because commercially available selectors may be mixtures of compounds differing in the degree of substitution and substituent positions. Mathematical description of these systems, which are highly relevant in analytical practice, can simplify search for optimal separation conditions. Also, it provides a useful insight into the separation mechanism. In this work, a model of electromigration of an analyte interacting with a mixture of two selectors is proposed and experimentally verified. This model results from a more general description of systems with an arbitrary number of selectors. The model shows that a selector mixture can be treated as a single selector if the ratio of the respective selector concentrations is kept constant. When the mixture is prepared intentionally, this description predicts, how separation potential of the mixture changes with its composition. Thus it allows the optimal composition and total...
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Study of complexation equilibria by capillary zone electrophoresis
Beneš, Martin ; Zusková, Iva (advisor) ; Coufal, Pavel (referee) ; Kašička, Václav (referee)
Capillary zone electrophoresis (CZE) is one of the most widely used analytical methods for separation of chiral analytes. In contrast to the other common chiral separation methods, chiral complexation agent is usually added directly to the background electrolyte to create enantioselective separation environment. Thus, the type and the concentration of chiral selector can be easily varied, which results in high flexibility of separation system. The detail understanding of electrophoretic separation systems with complexation involved is the main goal of this thesis. One of the most important advantages of capillary electrophoresis is existence of its complete mathematical model, which was implemented in several simulation programs. They can provide detail insight into the separation process or predict the separation results. However, none of the available simulators is suitable for complexing separation systems, which limits its applicability for chiral separation systems. For this reason, in the scope of this thesis we introduce the complete mathematical model of electromigration for separation systems with complexation agents. The model was implemented in our dynamic simulator Simul 5 and was verified experimentally. The new version of Simul 5 Complex provides the overall picture about the electrophoretic...
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