| Capillary electrochromatography (CEC) is a new micro-separation technique developed on the basis of high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). It combines the high selectivity of HPLC and the high efficiency of CE. It can be used for the rapid separation of both charged compounds and neutral compounds. It has opened up a new way to efficient micro-column separation technology.Capillary column is the core of CEC. Capillary monolithic column has been widely applied in CEC due to its easy preparation, good permeability, homogeneous structure, fast mass transfer and good chromatographic performance. As one kind of the most promising monolithic columns, organic-silica hybrid monolithic column has attracted increasing interests among the researchers. It does not need complicated modification process of inorganic-silica monolithic column. And compared to organic-polymer monolithic column, it dose not have the defect of easy swelling or shrinkage in organic solvents. Though there have been many reports on hybrid monolithic column, further investigation on its preparation technology is needed. For example, in order to prepare hybrid monolithic columns with more diverse functions, it is necessary to broaden the types of organic functional monomers. Among the exsisting preparation methods of hybrid monolithic columns, the bonding efficiency of organic functional monomers is still not high, so it is necessary to look for more effective preparation methods.The main contents of this thesis are summarized as follows:1. Based on the preparation system of the traditional vinyltrimethoxysilane (VTMS) hybrid monolithic columns, one-pot preparation of methacrylic acid (MAA) hybrid monolithic column was developed. In this method, MAA was used to replace acetic acid as a catalyst to catalyze the hydrolysis of VTMS and tetramethyl orthosilicate (TMOS). MAA acted as both the catalyst of hydrolysis and the organic functional monomer, so MAA could be bonded to the monolith. The influnces of reaction conditions including amount of MAA, amount of NaOH, amount of urea and reaction temperature on the structure of the monolith were investigated. The monolithic column exhibited high column efficiency for phenylmethanol and thiourea, up to73000plates/m and111000plates/m, respectively. Anilines and phenols could be well separated on the column by CEC. The separation of BSA tryptic digests demonstrated the desirable function of the column in the analysis of some complex samples. The study on the separation of different compounds indicated typical cation-exchange and reversed-phase chromatographic retention mechanisms of the column. 2. Based on trimethoxysilylpropanethiol (MPTS) hybrid monolithic columns, post-modification preparation of tertiary amine hybrid monolithic column bonded with2-(dimethylamino)ethyl methacrylate was developed. Firstly, MPTS hybrid monolithic column with active thiols was made by the sol-gel reaction of MPTS and TMOS, then2-(dimethylamino)ethyl methacrylate was bonded to the monolith via thiol-ene click chemistry to gain the tertiary amine hybrid monolithic column. The effects of reaction conditions including amount of acetic acid, TMOS/MPTS ratio and reaction temperature on the structure of the monolith were investigated. The influence of the concentration of derivative liquid on the permeability of the column was also been studied. The monolithic column exhibited high column efficiency for thiourea in both acidic and alkaline mobile phases, up to200000plates/m and180000plates/m, respectively. Anilines, phenols, bases and inorganic anions could be successfully separated on the column by CEC. The study on the separation of different compounds indicated typical anion-exchange and reversed-phase chromatographic retention mechanisms of the column.3. Based on MPTS hybrid monolithic columns, one-pot preparation of3-sulfopropyl methacrylate potassium (SPMA) hybrid monolithic columns was developed. By this mean, organic monomers could be directly added to the hydrolysis solution of TMOS and MPTS, then polycondensation and in situ thiol-ene click reaction between the precondensed siloxanes and organic monomers were simultaneously carried out in the capillary column at a low temperature. The one-pot method was firstly combined with the efficient click chemistry for the preparation of hybrid monolithic columns in this work. Compared to post-modification, the bonding efficiency of organic monomers was higher in the one-pot method. The influnces of reaction conditions including amount of urea, amount of MPTS, amount of SPMA and reaction temperature on the structure and chromatographic performance of the column were investigated. The monolithic column exhibited high column efficiency for phenylmethanol and thiourea, up to100000plates/m and250000plates/m, respectively. Alkylbenzenes, anilines and phenols could be well separated on the column by CEC. The study on the separation of different compounds indicated typical cation-exchange and reversed-phase chromatographic retention mechanisms of the column. |
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