Ion-exclusion chromatography of benzenecarboxylic acids on an unmodified silica-gel column

In order to demonstrate the effectiveness of two unmodified silica-gel (Develosil 30-5) columns (300×7.8 mm I.D.) used in series for the ion-exclusion chromatographic separation of mono-, di, tri- and tetrabenzenecarboxylic acids, the elution behavior of benzenecarboxylic acids and phenol was investigated. When using water as an eluent, many benzenecarboxylic acids were co-eluted and the separation was not satisfactory. However, when using 5 mM sulfuric acid (pH 2.0) as the eluent, excellent separation and high detection sensitivities for many benzenecarboxylic acids and phenol were achieved in 40 min using UV detection at 200 nm