Ion-exclusion chromatography of carboxylic acids on silica gel modified with aluminium

The modification of silica gel with aluminium by a coating method was effective for the preparation of a silica-based stationary phase, which acted as a cation exchanger under strongly acidic conditions. In order to expand the utility of the laboratory-made aluminium-adsorbing silica gel it was applied as a stationary phase to the ion-exclusion chromatography of various carboxylic acids. Good separations for both aliphatic carboxylic acids and benzenecarboxylic acids with a hydrophobic nature under acidic eluent conditions were achieved in 25 min.