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UBC Theses and Dissertations

Investigation of interacting species in capillary electrophoresis by experimental and simulation methods Sun, Ying


Capillary electrophoresis (CE) with complexation additives in the background electrolyte utilizes both equilibrium and electric field in the separation process. Therefore, a comprehensive understanding of the analyte migration behavior in CE processes becomes essential to effectively control the chemical separation process and to achieve the full potential of this powerful analytical technique. Computer simulation is one of the best ways to visualize the instantaneous behaviors of physicochemical systems. After the success of our first simulation program SimDCCE, a JAVA based computer simulation model of dynamic complexation capillary electrophoresis (CoSiDCCE) was developed based on the differential mass balance equation, the governing principle of analyte migration in all separation techniques. CoSiDCCE is highly efficient, and is capable of demonstrating various types of the affinity interactions between multiple species in CE in real time or faster. With the simulation program, a thorough study of the mechanism of vacancy affinity CE was carried out. Thermodynamic binding constant was estimated with nonlinear regression methods. Thirteen scenarios in four different combinations of migration orders of free protein, free drug, and their complexes formed were studied. The specific protein-ligand interactions were determined using CE-frontal analysis, one of the most effective CE modes. A new algorithm was derived to calculate the binding parameters for higher order specific interaction in the presence of non-specific interactions. Computer simulation was used to study the migration behaviors of all species in the DCCE process.CoSiDCCE was used to elucidate the determining factors that result in CE separations of amino acid enantiomers and predict the efficiency of the chiral selectors when used in other separation systems such as chromatography. With this program, the migration behavior of different species involved in the competitive dynamic complexation in chiral CE processes was investigated, and the change in migration orders in some chiral separations was explained. The binding constants and complex mobilities were also determined. In addition, a micellar electrokinetic chromatography method was developed to determine potentially anti-carcinogenic flavonoids in various wine samples. A systematic optimization of the separation buffer and concentration of surfactant was carried out to improve the reproducibility and sensitivity for the analysis of flavonoids.

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