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Electrokinetic chromatography in nonaqueous and mixed solvents: Determination of critical micellar concentration
Hamráková, Katarína ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
This thesis deals with the investigation of micelle formation following the addition of a surfactant to a background electrolyte in micellar electrokinetic chromatography and the transfer of these systems to nonaqueous and mixed solvents. The addition of organic solvents to the background electrolyte has a significant effect onmicelle formationandhence separation in electrokinetic chromatographyusinga micellar pseudo-stationaryphase. This effect has not yet been studied in depth. Information on the presence and properties of micelles in a given separation system is important for the understanding of separation processes but also for the development and optimization of analytical methods. In this work, the critical micellar concentration (CMC) of two surfactants, sodium dodecyl sulfate (SDS) and cetyltrimethylammoniumbromide (CTAB), was determinedby introducingthem into a mixed environment with non-aqueous solvents, acetonitrile and methanol. The critical micellar concentration was determined from the dependence of three variables on the surfactant concentration in the solution, namely, the effective mobility of the analytes and the viscosity and conductivity of the solution. Prior to the actual measurements of the effective mobility of the analytes, suitable analytes were selected,two which can...
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Development of electrophoretic method for determination of ethanolamines in antifreeze mixtures
Hamráková, Katarína ; Křížek, Tomáš (advisor) ; Coufal, Pavel (referee)
This bachelor thesis deals with development, optimization and testing of the applicability of electrophoretic method for determination of ethanolamines in antifreeze mixtures. The method was tested with the coolant matrix. For the determination of ethanolamines in antifreeze mixtures a capillary electrophoresis with undirect UV detection was used. Ethanolamines - monoethanolamine, diethanolamine and triethanolamine - are organic compounds, which are used in antifreeze mixtures as corrosion inhibitors because glycols, which are often used in such mixtures, can be, after exposure to high temperatures or oxygen from air, transformed to acids that cause corrosion. The method was optimized by selection of the appropriate composition of background electrolyte, its pH, appropriate ratio of individual buffer components and selection of a suitable internal standard. Background electrolyte was a buffer composed of 60 mM acetic acid and 30 mM histidine, pH 4.59 and lysine was used as an internal standard. Silica capillary with an internal diameter of 50 µm, a total length of 50.0 cm and an effective length of 41.5 cm was used for measurements. Measurement at short end was tested, as well as shortening the capillary to 35.0 cm with an effective length of 26.5 cm, which was further used. The sampling was...
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