title: Preparation of high efficiency and highly retentive monolithic silica capillary columns for reversed-phase chromatography by chemical modification by polymerization of octadecyl methacrylate.
abstract: High efficiency and highly retentive monolithic silica capillary columns were obtained by polymerization of octadecyl methacrylate using alpha,alpha'-azobis-isobutyronitrile (AIBN) as a free radical initiator. Hybrid type monolithic silica columns (25 cm total length x 200 microm I.D.) prepared from a mixture of tetramethoxysilane and methyltrimethoxysilane were used as a support. The effects of the monomer and the radical initiator concentrations in the reaction mixture were examined. The performance of the columns was tested in terms of column efficiency and retention behavior by using alkylbenzenes and a few other compounds as solutes and compared with that of hybrid monolithic silica columns modified with octadecylsilyl-(N,N-diethylamino)silane (ODS-DEA). Highly retentive monolithic silica columns were obtained by polymerization at high monomer concentrations. Although a decrease in column efficiency was observed with the increase in the monomer concentration in a feed mixture, an improvement in efficiency was achieved (a plate height value lower than 10 microm) by increasing an initiator concentration without significant variations in column retention properties. Results obtained by polymerization using other monomers are also presented to demonstrate the applicability of the preparation method.
authors.affiliation: Department of Biomolecular Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan. oscarnubu@yahoo.es
authors.forename: Oscar
authors.initials: O
authors.lastname: Núñez
authors.forename: Tohru
authors.initials: T
authors.lastname: Ikegami
authors.forename: Wataru
authors.initials: W
authors.lastname: Kajiwara
authors.forename: Kosuke
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Kanta
authors.initials: K
authors.lastname: Horie
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tanaka
mesh_terms: D001555:Benzene Derivatives / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation*; D008689:Methacrylates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009570:Nitriles / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide; D014498:Uracil / Q000302:isolation & purification
chemical_list: D001555:Benzene Derivatives; D008689:Methacrylates; D009570:Nitriles; D012821:Silanes; D014498:Uracil; D012822:Silicon Dioxide; C004526:azobis(isobutyronitrile)