title: Capillary electrochromatography with monolithic silica columns III. Preparation of hydrophilic silica monoliths having surface-bound cyano groups: chromatographic characterization and application to the separation of carbohydrates, nucleosides, nucleic acid bases and other neutral polar species.
abstract: Two synthetic routes have been introduced and evaluated for the preparation of hydrophilic silica-based monoliths possessing surface-bound cyano functions. In one synthetic scheme, the silica monolith was reacted in a single step with 3-cyanopropyldimethylchlorosilane to yield a cyano phase referred to as CN-monolith. In a second synthetic route, the silica monolith was first reacted with gamma-glycidoxypropyltrimethoxysilane (gamma-GPTS), followed by a reaction with 3-hydroxypropionitrile (3-HPN) to give a stationary phase denoted CN-OH-monolith. Although the gamma-GPTS was intended to play the role of a spacer arm to link the 3-HPN to the silica surface, this spacer arm became an integral part of the hydrophilic stationary phase. Thus, the CN-OH-monolith can be viewed as a double-layered stationary phase (i.e., stratified phase) with a hydroxy sub-layer and a cyano top layer. Due to its stronger hydrophilic character, the CN-OH-monolith yielded higher retention and better selectivity than the CN-monolith. The CN-OH-monolith was demonstrated in the normal-phase capillary electrochromatography (CEC) of various polar compounds including phenols and chloro-substituted phenols, nucleic acid bases, nucleosides, and nitrophenyl derivatives of mono- and oligosaccharides. The CN-OH-monolith yielded a relatively strong electroosmotic flow over a wide range of mobile phase composition, thus allowing rapid separation of the polar compounds studied.
authors.affiliation: Department of Chemistry, College of Arts and Sciences, 454A Physical Sciences, Oklahoma State University, Stillwater, OK 74078-3071, USA.
authors.forename: Darin
authors.initials: D
authors.lastname: Allen
authors.forename: Ziad
authors.initials: Z
authors.lastname: El Rassi
mesh_terms: D002241:Carbohydrates / Q000302:isolation & purification*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation / Q000379:methods*; D009696:Nucleic Acids / Q000302:isolation & purification*; D009705:Nucleosides / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D002241:Carbohydrates; D009696:Nucleic Acids; D009705:Nucleosides; D012822:Silicon Dioxide