title: Selectivity of some basic solutes on a poly(methyltetradecylsiloxane)-silica stationary phase.
abstract: Complex analyses of polar compounds, especially basic ones, require more selective stationary phases. The present paper describes a stationary phase prepared by thermal immobilization of poly(methyltetradecylsiloxane) onto chromatographic silica (PMTDS-SiO(2)). This stationary phase presents hydrophobic and ion-exchange interactions that confer both high retention and unique selectivities for basic solutes. The influence of ion-exchange interactions is confirmed by the increase in retention factors of basic solutes when the mobile-phase pH changes from acidic to neutral and by the decrease in retention factors when the mobile-phase pH changes from neutral to alkaline. The ion-exchange properties of the stationary phase are enriched in neutral mobile phase (pH 7-7.5) using soft Lewis bases such as tricine and tris as buffers but are suppressed in both acidic (pH 2.5-6) and highly alkaline mobile phases (pH≤10). Increasing both temperature and flow rate permits more rapid separations while maintaining the selectivity. The stability of the stationary phase is evaluated with acid, neutral and alkaline mobile phases.
authors.affiliation: Institute of Chemistry, University of Campinas, Campinas, SP, Brazil. marcelborgesb@gmail.com
authors.forename: Endler M
authors.initials: EM
authors.lastname: Borges
authors.forename: Carol H
authors.initials: CH
authors.lastname: Collins
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D009682:Magnetic Resonance Spectroscopy; D012822:Silicon Dioxide / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet
chemical_list: D012833:Siloxanes; C513729:poly(methyltetradecylsiloxane); D012822:Silicon Dioxide