| 19572559 |
Bocian S, Vajda P, Felinger A, Buszewski B: Excess adsorption of commonly used organic solvents from water on nonend-capped C18-bonded phases in reversed-phase liquid chromatography. Anal Chem. 2009 Aug 1;81(15):6334-46.
The excess adsorption isotherms of methanol, 2-propanol, acetonitrile, and tetrahydrofuran from water were measured on five silica-based packing materials by the minor disturbance method. The adsorbed amount of solvents was calculated per silica gel surface and per modeled surface of bonded phase which seem to give more correct data. Columns used in this study were nonend-capped with different coverage density of bonded C18 ligands. It allows investigating the influence of the density of residual silanols on the solvent adsorption and on adsorption properties of the surface. The stationary phases were characterized by elemental analysis and low-temperature nitrogen adsorption. Geometric parameters of the stationary phases in the column were measured by inverse size exclusion chromatography. The relative adsorption of the organic solvents from water informs on the heterogeneity of the stationary phases and on the accessibility of the unreacted silanol groups to the mobile phase. The differences in the organic solvent and water molecules for interaction with organic ligand and residual silanols are used for the estimation of the surface heterogeneity. |
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