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...

The final goal of this study is to establish a microscale analysis method that allows solution phase characterization of interactions between β2-glycoprotein I (β2gpI) and some of its ligands. Human β2gpI is a phospholipid- and heparin-binding plasma glycoprotein. The physiological role of the protein in normal blood coagulation is not entirely known, nor is its role in autoimmune diseases characterized by blood clotting disturbances (thrombosis). Quantitative binding data of β2gpI interactions with some of its ligands may help elucidating the mechanisms behind these diseases and in the development of new approaches for diagnostics, prevention, and therapy. In this thesis, capillary electrophoresis (CE) was used as methodological platform for the interaction studies. The analysis of peptides and proteins by CE is desirable due to low sample consumption, possibilities for non-denaturing and highly effective separations. The first objective of this thesis was to find an approach to prevent charge dependent adsorption of β2gpI to the inner surface of the capillaries. Analyte adsorption at the negatively charged inner surface of fused silica capillaries is detrimental to interaction analyses. This phenomenon is especially pronounced in the analysis of basic proteins and proteins containing exposed positively charged domains, such as β2gpI. A new strategy to suppress these solute-wall interactions was devised, investigated and optimized. This strategy exploits the pH hysteresis behavior of fused silica surfaces, by simply performing an acidic pretreatment of the capillary. The results in this thesis show that the acidic pretreatment efficiently prevents protein adsorption. / <p>Papper 4 Estimation of the amount of β₂-glycoprotein I adsorbed at the inner surface of fused silica capillaries after acidic, neutral and alkaline pretreatment ingick som manuskript i avhandlingen, nu publicerad.</p>

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<p> Affinity capillary electrophoresis (ACE) is a versatile technique for assessing non-covalent molecular interactions in free solution provided that there are significant changes in apparent analyte mobility as a result of specific complexation. The thermodynamics of receptor binding are vital for controlling the selectivity in molecular recognition, which are dependent on the electrolyte composition of solution. In addition, the conformational properties of the complex (e.g., size, shape) can also contribute a secondary influence on receptor selectivity that has been relatively unexplored in ACE to date. In this study, dynamic 1:1 host-guest inclusion complexation involving a anionic resorcin[4]arene with a group of neutral corticosteroids was examined by ACE, where the macrocycle serves as both an intrinsic buffer and electrokinetic host. The tetraethylsulphonate derivative of 2-methylresorcin[4]arene (TESMR) was first synthesized via an acid-catalyzed condensation reaction, which was then fully characterized in terms of its weak acidity (pKa), mobility, UV spectral and buffer capacity properties. TESMR solutions were demonstrated to have stable intrinsic buffer and ion transport properties at pH 7.5 even at low ionic strength. It was determined that over a 200 % enhancement in the apparent binding constant (KB) was realized by ACE when using TESMR as an intrinsic buffer at pH 7.5 relative to an extrinsic sodium phosphate buffer system, which was also confirmed by 1H-NMR. The coupling of thermodynamic (KB) and electrokinetic (μep, AC) factors associated with complex formation in buffered aqueous solutions that minimize the effects of extrinsic electrolytes serves to enhance enthalpy-driven molecular recognition processes by ACE.</p> / Thesis / Master of Science (MSc)

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...

Capillary electrophoresis is one of the prominent analytical separation methods. Currently, many computer programs exist which are able to predict the result of an electrophoretic experiment. Firstly, there are programs based on numerical solving of corresponding continuity equations and equations of chemical equilibria. Secondly, there are programs based on approximative models of capillary electrophoresis. Programs belonging to the first group are applicable to a wide range of modes of capillary electrophoresis and provide a precise solution. Their disadvantage is though a considerable time demand. On the other hand, the approximative models give the results almost immediately and, in addition, provide some theoretical relationships which are useful for optimization of the separation process. This dissertation thesis is focused on improvement and extension of validity of existing approximative models of capillary electrophoresis. As a part of this thesis, a model capable of a full-blown description of capillary electrokinetic chromatography is introduced. This model is implemented into program PeakMaster 6. The attention is also paid to a nonlinear model of electromigration without diffusion. This model enables a very good description of electromigration dispersion including effects related to...

Motion of ions under the influence of electric field has been a subject of scientific interest for many decades. Capillary electrophoresis in particular benefited greatly from this research and mathematical models of electromigration applicable to capillary electrophoresis have been developed. As the sophistication of the models grew, so did the computational demands to evaluate them. In order to fully exploit the possibilities of advanced mathematical models a computer implementation capable of solving non-trivial problems at sufficient speed is necessary. This dissertation thesis explores applications of computer implementations of mathematical models re- lated to electromigration in two different areas. The main focus of this thesis is on the topic of linear theory of electromigration. We discuss the extension of the linear theory of electromigration beyond of just acid-base equilibria and computer implementation of this extented theory which is specialized to include complex-forming equilibria in order to be able to deal with affinity capillary electrophoresis prob- lems. Some technical aspects of the computer implementation are also discussed. This is followed upon by investigating certain selected affinity capillary electrophoresis systems. The purpose of this investi- gation is to re-derive...