Analysis of oligogalacturonic acids with 50 or fewer residues by high-performance anion-exchange chromatography and pulsed amperometric detection

Abstract

Underivatized oligogalacturonic acids with a degree of polymerization (DP) ranging from 2 to 50 have been separated for the first time on a high-performance CarboPac PA1 pellicular anion-exchange stationary phase column. Baseline separation of these pectic fragments was accomplished using a nonlinear gradient of pH 6 potassium oxalate buffer as the mobile phase. Acetate buffer linear gradients were also useful as mobile phases, but only for separations of oligogalacturonic acids that were soluble in this solvent (DP < 20). Additionally, oligogalacturonic acid separations were accomplished on a lower capacity AS4A stationary phase column. Triple pulse amperometric detection was selective, sensitive, and reproducible, nevertheless, oligopalacturonic acid response factors were affected by DP and compositional changes in the mobile phase.