title: Monolithic silica columns for high-efficiency separations by high-performance liquid chromatography.
abstract: Generation of a large number of theoretical plates was attempted by capillary HPLC. Monolithic silica columns having small skeletons (ca. 2 microm) and large through-pores (ca. 8 microm) were prepared by a sol-gel method in a fused-silica capillary (50 microm I.D.), and derivatized to C18 phase by on-column reaction. High external porosity (>80%) and large through-pores resulted in high permeability (K= 1.2 x 10(-2) m2). The monolithic silica column in the capillary produced a plate height of about 12 microm in 80% acetonitrile at a linear velocity of 1 mm/s. Separation impedance, E value, was found to be as low as 200, that was about an order of magnitude lower than reported values for conventional columns packed with 5 microm particles. Reproducibility of preparation within +/- 15% was obtained for column efficiency and for pressure drop. It was possible to generate 100,000 plates by using a 130-cm column at very low pressure (<7 kg/cm2). A considerable decrease in column efficiency was observed at high linear velocity, and for solutes with large retention factors due to the slow mobile-phase mass transfer in the large through-pores. The monolithic silica columns, however, showed performance beyond the limit of conventional particle-packed columns in HPLC under favorable conditions.
authors.affiliation: Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Ishizuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Minakuchi
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hirao
authors.forename: Ken
authors.initials: K
authors.lastname: Hosoya
authors.forename: Tohru
authors.initials: T
authors.lastname: Ikegami
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tanaka
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide
chemical_list: D012822:Silicon Dioxide