| The silica-based phases are the most widely used materials in HPLC. Silica supports are superior to other supports in terms of efficiency, rigidity and performance. However, there are several disadvantages with silica-based materials such as severe peak tailing in the chromatography of basic compounds, limited pH stability and irrproducibility for the same chemistry columns. The defects of silica limit its application in some important fields. There has been an increasing importance in application of titania-based HPLC packings for their excellent chemical, high-temperature, mechanical stability as well as bioanalysis suitability. It would become a new generation of chromatographic media for separation science.The goal of this study is to prepare uniform titania-based supporst by layer-by-layer (LbL) self-assembly technique, which have both silica's and titania's virtues. Meanwhile the normal-phase and reversed-phase chromatogram performance were studied.The major work includes the following aspects:1. The uniform titania nanoparticle multilayers /micrometer-sized silica particle (TiO2/SiO2) was prepared for HPLC support material by layer-by-layer (LbL) self-assembly technique Utilizing the LbL self-assembly method with low-cost TiCl4 as the raw material and as SiO2 cores. The influence of experimental parameters, times of self-assembly and calcining temperature on the surface condition as well as the content were studied. The result show that HC1 concentrion 4.0mol/L,assembly temperature 80 °C, assembly layers 8 and calcine temperature 400°C are the best experimental condition.2. Utilizing the LbL self-assembly method with low-cost nanomicrometer titania particles as the raw material and as SiO2 supports, successfully obtained nano-structure TiO2/SiO2 composite. The influence of times of assembling and assemble medium on the surface condition and content of TiO2 were studied. The result show : we can obtained TiO2/ SiO2 with different titania thickness,however it's titania shell has some defects.3. The parameters of TiO2/ SiO2 core-shell composite were investigated. The average diameter of the TiO2/ SiO2 microspheres determined by silica is 5um. The plot of nitrogen adsorption/ desorption isotherms of TiO2/ SiO2 composite belongs to the IV isotherms and HI hysteresis loop. The particle size and pore size distribution arenarrower .The above result prove that TiCVSiC^ is suitable for HPLC Packing Materials;the acidity TiCVSiC^ is lower than silica and the pH stability of TiCVSiC^ is superior to silica-, comparing with S1O2, the pH stability of TiO2/SiC>2-8 improved obviously. So it is concluded that the support is useful as a packing material for HPLC especially when it's used to separat basic compounds.4. The TiC>2/SiO2 supports of normal chromatography displayed that high efficiency and good selectivity were obtained for basic compounds and weak retention on neutral compounds;The Cis-TiCVSiC^supports (ODT) reverse-chromatography has the good chromatographic features, high efficiency and good selectivity for basic compounds and neutral compounds. The results show the ODT reverse-chromatography takes on a good application prospect.
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