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Modification of inner capillary surface for electrophoretic separations of liposomes
Píplová, Renata ; Křížek, Tomáš (advisor) ; Čokrtová, Kateřina (referee)
Electroosmotic flow is one of the main factors that affect the resolution of separations in capillary electrophoresis and its modification is often necessary. One way of modification of the electroosmotic flow is the use of dynamic or permanent coating of the inner capillary surface. Such modifications during liposome separation can also reduce the tendency of liposomes to adsorb to the capillary surface. The aim of this work was to find a stable coating that will sufficiently eliminate the electroosmotic flow and to test its effect on the separation of liposomes. At first, the dynamic coatings of the capillary with Pluronic F-127, polyvinylpyrrolidone K30, polydiallyldimethylammonium chloride, polyethylene glycol and polyvinyl alcohol were tested using four different methods. Individual polymers and methods differed in the rate of elimination of the electroosmotic flow as well as in the stability of the capillary coatings. Dynamic coatings with Pluronic F-127, polyvinylpyrrolidone K30 and polydiallyldimethylammonium chloride were selected for further liposome separation testing. Fluorescently labeled liposomes were separated using capillary electrophoresis with laser-induced fluorescence detection and the mobilities of liposomes separated using capillaries with different coatings were determined....
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Separation of liquid crystal forming substances using non-aqueous capillary electrokinetic chromatography
Čokrtová, Kateřina ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
Liquid crystals are widely used in electronics, medicine and other fields. Analytical separations are important in the development of new liquid crystals to control the purity of synthesized substances. The sample analysis is important for detection of impurities formed during synthesis and for determination of chiral purity of the substance. Liquid crystal-forming substances cannot be separated by capillary zone electrophoresis due to the absence of readily ionizable groups. Electrokinetic chromatography is a method in which a suitable surfactant is added to the background electrolyte. The uncharged substances then interact with the electrically charged surfactant to obtain an effective charge. Separation can occur if they interact differently with the added surfactant. Another problem complicating the analysis is the very low solubility of analytes in water. Separations in this work were therefore carried out under non-aqueous conditions in acetonitrile. However, under these conditions a poor repeatability of the migration times of the substances was observed. Therefore, capillaries with differently coated inner walls were used in subsequent measurements. Surface modification should improve the repeatability of migration times. Several types of capillary coating have been tested. Dynamic coating...
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Effect of background electrolyte anions on markers of electroosmotic flow in capillary electrophoresis
Čokrtová, Kateřina ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
Mobility of the electroosmotic flow is an important quantity in capillary electrophoresis because its value is needed to determine the effective electrophoretic mobility of analytes. The effective electrophoretic mobility is used for electrophoretic determination of physico-chemical constants, such as dissociation constants or stability constants, but it is also important in analytical chemistry because identification of analytes is based on the value of the effective mobility. The most common way to measure electroosmotic flow is to add a neutral substance to the sample. However, the neutral substance can gain electrophoretic mobility due to interactions with the components of the background electrolyte. This may cause an inaccurate determination of the velocity of the electroosmotic flow. The aim of this work was to measure the mobility of several common and less frequently used markers in the background electrolyte containing different anions and to find suitable marker - anion combinations in order to avoid major measurement errors. Relative mobility of eight markers in the pure background electrolyte and in the background electrolyte containing a salt of the studied anion - sodium chloride, sodium perchlorate or sodium sulphate - was measured and related mobility of thiourea. Acetate buffer...
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