High-performance liquid chromatographic separation of oligogalacturonic acids on a cyclomaltoheptaose (β-cyclodextrin) bonded-phase column

A cyclomaltoheptaose (β-cyclodextrin) bonded-phase HPLC column was used for the first time to separate acidic oligosaccharides. Oligogalacturonic acids up to a degree of polymerization (dp) of 7 were separated with a 50:50 acetonitrile-sodium phosphate-buffered (pH 5) mobile phase and up to dp 17 with an isocratic pH 5.0, sodium phosphate-buffered mobile phase. A sodium acetate gradient elution allowed for improved resolution of all oligogalacturonic acids, up to a dp value of at least 24. Although the stationary phase contained no cationic or readily ionizable groups, these separations appeared to be governed by a classical anion exchange-type mechanism. The β-cyclodextrin-bonded phase, which displayed exceptional stability over one year of use, is a useful alternative to silica gel- or organic polymer-based anion exchangers for HPLC of acidic carbohydrates.