Development of monolithic silica columns in capillary for high-speed and high-performance HPLC

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The development of porous monolithic silica columns in capillary for micro-HPLC was studied to achieve higher performance than columns packed with particles. Following experiments were carried out.(1) Preparation of a monolithic silica column in a capillary from alkoxysilanes.(2) Preparation of monolithic silica columns in capillaries of various sizes, 25-250 μm.(3) Study on the effect of domain size (through-pore size + silica skeleton size) and the ratio between through-pore size and skeleton size on the performance.(4) Preparation of ultrahigh efficiency monolithic silica columns.(5) Preparation of monolithic silica columns showing high efficiency in a short time.(6) Study on the factors determining band-broadening in a monolithic silica column.(7) Evaluation of monolithic silica columns in micro-HPLC and CEC.(8) Application of monolithic silica columns for the separation of various types of compounds including bases, dissociable compounds, and hydrocarbons.Following results were ob … More tained.(1) It is possible to prepare network-type monolithic silica attached to the tube wall of fused silica capillary having 50-250 μm diameter.(2) Decrease in domain size showed similar effects as the decrease in particle size in a particle-packed column, causeing higher column pressure drop and higher column efficiency.(3) A monolithic silica capillary column of 100 μm, 250 cm gave 200, 000 - 300, 000 theoretical plates with to = 1000 s.(4) A monolithic silica capillary column with through-pores = 1.5 μm and skeleton size 0.8 μm gave 10.000 theoretical plates with to = 15 S.(5) The band-broadening in a monolithic silica column is dominated by A-term, or the contrubution of slow mass transfer in mobile phase, especially when the monolith possesses large through-pore size. Monoliths having small domain size showed the major contibution of stationary phase mass transfer.(6) Hybrid-type monolithic silica columns showed high performance for the separation of various types of compounds including bases, b-blockers, steroids, ketones, phthalates, aicohols, and hydrocarbon of various structures.Monolithic silica columns in 200 μm capillary can show performance 2 - 3 times higher than particle-packed columns under common conditions and are relatively easy to use. They can be applied for the separatin of a wide range of compounds. Thus they are close to practical use. (1) Preparation of larger-sized capillary, (2) various surface monofication by on-column reactions(3) optimization of domain structures, and (4) theoretical and experimental study on band-broadening in monolithic silica columns will be practical and basic subjects to study in this area. Other study will include the preparation of monolithic silica in a chip channels and multidimensional chromatography in a microscale HPLC. Less