title: Synthesis and characterization of silica-based hyper-crosslinked sulfonate-modified reversed stationary phases.
abstract: A novel type of silica-based sulfonate-modified reversed phase ((-)SO3-HC-C8) has been synthesized; it is based on a newly developed acid stable "hyper-crosslinked" C8 derivatized reversed phase, denoted HC-C8. The (-)SO3-HC-C8 phases containing controlled amounts of sulfonyl groups were made by sulfonating the aromatic hyper-crosslinked network of the HC-C(8) phase at different temperatures. The (-)SO3-HC-C8 phases are only slightly less hydrophobic than the parent HC-C8 phase. The added sulfonyl groups provide a unique strong cation-exchange selectivity to the hydrophobic hyper-crosslinked substrate as indicated by the very large C coefficient as shown through Snyder's hydrophobic subtraction reversed-phase characterization method. This cation-exchange activity clearly distinguishes the sulfonated phase from all other reversed phases as confirmed by the very high values of Snyder's column comparison function F(s). In addition, as was found in previous studies of silica-based and zirconia-based reversed phases, a strong correlation between the cation-exchange interaction and hydrophobic interaction was observed for these sulfonated phases in studies of the retention of cationic solutes. The overall chromatographic selectivity of these (-)SO3-HC-C8 phases is greatly enhanced by its high hydrophobicity through a "hydrophobically assisted" ion-exchange retention process.
authors.affiliation: Department of Chemistry, University of Minnesota, Smith and Kolthoff Hall, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Luo
authors.forename: Lianjia
authors.initials: L
authors.lastname: Ma
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Peter W
authors.initials: PW
authors.lastname: Carr
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D015394:Molecular Structure; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry*; D013450:Sulfones / Q000737:chemistry*; D013457:Sulfur Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D013450:Sulfones; D013457:Sulfur Compounds; D012822:Silicon Dioxide