Preparation And Applications Of Silica Nanoparticles-functionalized Hybrid Monolithic Capillary Columns

The study of capillary electrophoresis (CE) is becoming more and more hot inrecent years. As the core component of CE, the study of capillary column also hasmade great development, of which the organic-inorganic hybrid monolithic column isparticularly prominent. Beacause of its diverse surface chemistry, good mechanicalperformance, high column efficiency and easy making, hybrid monolithic column hasbecome the mainstream of columns’ study for capillary electrochromatography. Onthe other hand, with the rapid development of materials science in recent decades,new materials bring new functions, and also bring new approaches for developing newanalytical methods. Hence, the integration of new materials into CE methodology ismore and more important. Based on the situation mentioned above, this thesis isfocused on introducing silsesquioxane into hybrid monolithic column. The main workof this thesis is summarized as follows:1. Based on trimethoxysilylpropanethiol (MPTS) hybrid monolithic columns,multistep post-modification preparation of methylacrylic-silsesquioxane (MA-POSS)hybrid monolithic column bonded with3-mercapto-1-propanesulfonate was developed.The proposed column exhibited high column efficiency for thiourea andphenylmethanol. Different types of compounds including anilines, phenols and baseswere successfully baseline separated by capillary electrochromatography (CEC).The separation of theses analytes on the column indicated typical reversed-phase andanion-exchange chromatographic retention mechanisms. This work provided a newway to prepare silsesquioxane hybrid monolithic columns through multisteppost-modification. Meanwhile, MPTS hybrid monolithic columns can be a goodbasement for post-modification processes.2. Based on MPTS hybrid monolithic columns, one-step post-modificationpreparation of3-mercapto-1-propanesulfonate modified octavinyloctasilasesquioxane(MPS-OVS) hybrid monolithic column was developed. In order to convert theuncharged OVS into a charged silsesquioxane,3-mercapto-1-propanesulfonate (MPS)was used to modify the OVS through thiol-ene click chemistry for the first time. Withthe MPS-OVS, reversed-phase and anion-exchange chromatographic retentionmechanisms can be found in the separation of nilines, phenols and bases by CEC.The one-step post-modification strategy is proved to be a promising method for preparing silsesquioxane hybrid monolithic columns using modified silicananoparticles.3. A cage-like silica nanoparticles-functionalized silica hybrid monolith has beenprepared via “one-pot” process. In this process, the polycondensation of hydrolyzedalkoxysilanes and in situ reaction of mercapto-propyltrimethoxysilane (MPTS) withsodium3-mercapto-1-propanesulfonate modified octavinyloctasilasesquioxane(MPS-OVS) simultaneously occurred in a pretreated capillary. The characterizationand evaluation results indicated that the obtained MPS-OVS hybrid monolithiccapillary column has homogeneous macroporous morphology with a permeability of5.37×10-13m2and strong electroosmotic fow (EOF) over a wide pH range from2.7to11.2. The EOF on the MPS-OVShybrid monolithic column reached its maximum of0.327cm2kV-1s-1at pH9.7. The best theoretical efficiency of~470000plates/m wasobtained for2-aminophenol in CEC. Anilines and phenols were well separated on theMPS-OVS hybrid monolithic column by CEC, indicating typical reversed-phase andcation-exchange chromatographic retention mechanisms of the column. The monolithwas further applied to the separation of bovine serum albumin (BSA) tryptic digests,and the result indicated its potential in the analysis of some complex samples.