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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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System peaks in elektromigration systems with complexing agents
Dvořák, Martin ; Gaš, Bohuslav (advisor) ; Coufal, Pavel (referee)
Capillary zone electrophoresis (CZE) is a widely used analytical method. CZE is described theoretically very well and there are many simulation programs, which enable one to predict results of electrophoretic separations, and alternatively to study phenomena taking place during the electrophoretic separation in detail. The CZE method is not only an analytical method, but is often used for determination of many physical parameters of compounds, such as stability constants or complex mobilities. Among methods most often used for determination of complexation parameters belongs the affinity capillary electrophoresis (ACE). Its alternative is the vacancy affinity capillary electrophoresis (VACE). Whereas by the ACE method the stability constant is determined from the dependence of the analyte effiective electrophoretic mobility on the background electrolyte (BGE) composition, in the case of the VACE system peaks are used for this purpose. In this work the legitimacy of using system peaks in the VACE method for determination of stability constants was investigated. Several approaches dealing with the concentrating of complexing agent in the peak area were compared, both for the ACE and the VACE method. Two different kinds of electrophoretic systems were studied. In the first one, neutral cyclodextrin was used as...
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Determination of stability constants of [Gly6]-antamanide complexes with small cations by affinity capillary electrophoresis
Pangavhane, Sachin ; Makrlík, E. ; Ruzza, P. ; Kašička, Václav
Affinity capillary electrophoresis (ACE) was employed for the determination of apparent stability constants Kst of complexes of cyclic peptide [Gly6]-antamanide ([Gly6]-AA) with alkali and alkali-earth metal ions: Li+, Na+, K+, Rb+, Cs+, NH4+, and Ca2+. Kst was determined from the dependence of effective mobility of [Gly6]-AA on the concentration of these ions in the background electrolyte using the non-linear regression analysis. Kst were found to be in the range 13.3 – 26.3.
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Study of DNA oligonucleotides interactions with ethidium bromide by partial-filling affinity capillary electrophoresis
Růžička, Martin ; Koval, Dušan ; Kašička, Václav
A partial filling affinity capillary electrophoresis was developed and applied to investigation of non-covalent molecular interactions between double stranded DNA oligonucleotide (Dickerson dodecamer) and classical DNA intercalator ligand –ethidium bromide (EtBr). Binding constants of DNA EtBr complexes were determined from the dependence of migration time changes of DNA oligomer (applied as analyte) on the length of ligand zones introduced beforehand as plugs of various lengths in hydroxypropylcellulose coated fused silica capillary. Binding constants of DNA-EtBr complex were found to be in the range 4.2 x 103 – 1.5 104 L/mol.
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