| With the rapid development of various fields of study in proteomics, metabonomics, the modernization of Chinese traditonal medicine, environmental protection and so on, strong polar and hydrophilic small molecules are rapidly becoming the important objects of study in analytical chemistry and biochemistry fields. However, the separation of polar compounds and highly hydrophilic compounds is difficult on conventional columns. This greatly limits their application. Hydrophilic interaction chromatography (HILIC), as a new type of chromatographic separation mode, came into being and has been proved as a powerful technique in qualitative and quantitive analysis of various kinds of polar and hydrophilic samples. So far, type of HILIC stationary phase is very limited. Therefore, the research for preparation and application of HILIC stationary phase has very important significance. Based on these considerations, four novel silica-based HILIC stationary phases were prepared in this paper. Moreover, their separation performance and mechanism were studied.The contents are as follows:1. An imidazoline was prepared by solvent-free microwave-assisted organic synthesis and immobilized on porous silica particles by polymerization. The resulting material was composed of both hydrophobic alkyl ester chains and hydrophilic imidazoline rings, which gave it both hydrophilic interaction and reversed-phase characteristics. The titration curve suggests that the new material has buffering capacity and acquires increasing positive charge over the pH range9-4and is "zwitterionic" in the upper part of this pH range. Through investigating the effect of column temperature, the water content, pH and ion strength of mobile phase on the retention time of polar compounds in highly organic eluents, it was found that the new material could be used as a hydrophilic interaction liquid chromatography stationary phase which involved a complex retention process consisting of partitioning, surface adsorption and electrostatic interactions. In addition, the retention behavior of aromatic compounds in different mobile phase conditions was also studied, which showed the new material mainly exhibited a partitioning mechanism in the reversed-phase liquid chromatography (RPLC) mode. The separation of six water-soluble vitamins and five aromatic compounds were achieved by using the new material in the HILIC and RPLC modes, respectively.2. The mixed sulfated/methacryloyl polysaccharide derivative was prepared and successfully immobilized onto the surface of porous silica particles by polymerization. Polysaccharide derivative was calculated as10.33%in the stationary phase prepared. The new stationary phase (PMSP) showed both HILIC and per aqueous liquid chromatography (PALC) characteristics. The effects of column temperature, the water content, pH and ion strength of mobile phase on the retention time of test compounds in highly aqueous eluents were investigated to evaluate the PALC features of PMSP. The column efficiency is about31000plates/m for benzoic acid in water/ACN (97/3, v/v) mobile phase at a flow rate of1.0mL/min. Compared with C18column, the PMSP had shorter retention time for weak polar and non-polar compounds, but also showed stronger retention for strong polar compounds. It indicated that PALC was a suitable mode of chromatography as replacement of HILIC and complementarity of reversed-phase liquid chromatography (RPLC).3. Carbon nanoparticles (CNPs)(6～18nm in size) were prepared by refluxing corn stalk soot in nitric acid. The obtained acid-oxidized CNPs are soluble in water due to the existence of carboxylic and hydroxyl groups. C13NMR measurement shows the CNPs are mainly of sp2and sp3carbon structure different from CNPs obtained from candle soot and natural gas soot. Furthermore, these CNPs exhibit unique photoluminescence properties. Interestingly, the CNPs might be exploited to immobilize on the surface of porous silica particles as chromatographic stationary phase. The resultant packing material was evaluated by high-performance liquid chromatography, indicating that the new stationary phase could be used in HILIC and PALC modes to separate polar compounds and highly hydrophilic compounds lack of retention on conventional reversed-phase columns. The separation of five nucleosides, four sulfa compounds and safflower injection was achieved by using the new column in the HILIC and PALC modes, respectively.4. Cyclopeptide stationary phase, cyclo[-Ala-Ala-Ala-Glu-], was synthesized by solid-phase synthesis method. Each amino acid coupling step was monitored by the ninhydrin test using UV/Visible spectrophotometry. The proposed material was characterized by UV spectra, FT-IR spectra, elemental analysis and thermogravimetric analysis, which proved the successful immobilization of cyclo[-Ala-Ala-Ala-Glu-] on the silica support. The obtained stationary phase had the stereoselectivity for polycyclic aromatic hydrocarbon such as athracene. Retention behavior of polar compounds was studied through varying the water content, column temperature, pH and ion strength in corresponding acetonitrile-rich and water-rich mobile phases. The separation of five nucleosides, five sulfa compounds and phenol compounds were investigated by using the new column in acetonitrile-rich and water-rich mobile phases, respectively.
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