title: Carboxylate modified porous graphitic carbon: a new class of hydrophilic interaction liquid chromatography phases.
abstract: Stationary phases for hydrophilic interaction liquid chromatography (HILIC) are predominantly based on silica and polymer supports. We present porous graphitic carbon particles with covalently attached carboxylic acid groups (carboxylate-PGC) as a new HILIC stationary phase. PGC particles were modified by adsorbing the diazonium salt of 4-aminobenzoic acid onto the PGC, followed by reduction of the adsorbed salt with sodium borohydride. The newly developed carboxylate-PGC phase exhibits different selectivity than that of 35 HPLC columns, including bare silica, zwitterionic, amine, reversed, and unmodified PGC phases. Carboxylate-PGC is stable from pH 2.0 to 12.6, yielding reproducible retention even at pH 12.6. Characterization of the new phase is presented by X-ray photoelectron spectroscopy, thermogravimetry, zeta potentials, and elemental analysis. The chromatographic performance of carboxylate-PGC as a HILIC phase is illustrated by separations of carboxylic acids, nucleotides, phenols, and amino acids.
authors.affiliation: Department of Chemistry, University of Alberta, Gunning/Lemieux Chemistry Centre, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: M Farooq
authors.initials: MF
authors.lastname: Wahab
authors.forename: Mohammed E A
authors.initials: ME
authors.lastname: Ibrahim
authors.forename: Charles A
authors.initials: CA
authors.lastname: Lucy
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods; D006108:Graphite / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D056951:Photoelectron Spectroscopy / Q000379:methods*; D016062:Porosity
chemical_list: D002264:Carboxylic Acids; D002244:Carbon; D006108:Graphite