Preparation Of Silica-based Polar Stationary Phases And Application In Electrochromatography

Silica-bonded polar stationary phases have excellent chromatographicproperties, and are more suitable for separation of polar substances, now gettingmore and more attention. Capillary electrochromatography(CEC) is an effectivemicroseparation technique, which combines the adtantages of capillaryelectrophoresis(CE) and high performance liquid chromatography(HPLC).Stationary phases play a vital part in CEC and the research of the preparation ofstationary phases has become the research focus in CEC. The thesis aims to preparenew silica-bonded polar stationary phases, and evaluate its performance in CEC.Thsis thesis consists of four chapters, main points are listed as following:In Chapter1, research progress of silica-bonded stationary phases using in CEChas been reviewed, with the emphasis on silica-bonded polar stationary phases.Onthis basis, the experimental design and research programs have been proposed.In Chapter2, preparation of new stationary phase for CEC. Based on amino-propyl silica gel, used three different methods a new asparagines-modifiedsilica-bonded polar stationary phase was preparated. This new silica-bonded polarstationary phase was charactered by elemental analysis, X-ray photoelectronspectroscopy, UV-visible spectrum, through which the feasibility of the threedifferent methods was comparared. With this guidance, another new, more polarkanamycin-modified silica-bonded polar stationary phase was preparated.In Chapter3, evaluation of asparagines-modified silica-bonded polar stationaryphase in CEC. The retention mechanism as well as the factors that affected theelectroosmotic flow has been investigated in detail. The results showed thatasparagines-modified silica-bonded polar stationary phase has the retained mode ofhydrophilic interaction, and the electroosmotic flow was mainly affected by the ratioof acetonitrile and pH value of buffer, the impact of ion concentration in buffer wasno obvious. Neutral polar substances phenol, catechol, pyrogallol were wellseparated, with the separation degrees of0.12,0.32,0.81, respectively, the main retention mechanism was hydrophilic interaction. Strong polar and chargedsubstances nucleoside were also separated, the ratio of acetonitrile, pH value ofbuffer, ion concentration in buffer, supplementary pressure, applied voltage, andpump flow rate were investigated, the main retention mechanism was hydrophilicinteraction and ion-exchange, the separation degrees were RUG=1.09，RGA=1.10，RAC=1.68.In Chapter4, evaluation of kanamycin-modified silica-bonded polar stationaryphase in CEC. The retention mechanism as well as the factors that affected theelectroosmotic flow has been investigated in detail. The results showed that theretained mode was hydrophilic interaction mode, and kanamycin-modifiedsilica-bonded polar stationary phase was more polar, the electroosmotic flow wasmainly affected by the ratio of acetonitrile and pH value of buffer, the impact of ionconcentration in buffer was no obvious. Phenol, catechol, pyrogallol were wellseparated, with the separation degrees of0.20,0.40,0.95, respectively, better thanasparagines-modified silica-bonded polar stationary phase, the main retentionmechanism was hydrophilic interaction. Strong polar and charged substances nucleicacid bases were well separated, the ratio of acetonitrile, pH value of buffer, ionconcentration in buffer, supplementary pressure, applied voltage, and pump flowrate were investigated, the main retention mechanism was hydrophilic interactionand ion-exchange, the separation degrees were RUG=1.09，RGA=1.10，RAC=1.68,peak broadening was well avoided. Mono-nucleotide was also separated with goodpeak symmetry.