Oligogalacturonic acids were separated using HILICpak VN-50 4D, a polymer-based HILIC column. Since galacturonic acid, which is a constituent sugar, has a carboxyl group, it is necessary to keep the eluent under acidic conditions to suppress dissociation. Using a gradient condition of 1 % formic acid aqueous solution and acetonitrile, oligogalacturonic acids were detected with an evaporative light scattering detector (ELSD).  Sharp peaks were obtained and it was possible to confirm up to dp 11.

Sample : 10 µL
Oligogalacturonic acids 5 mg/mL
(in 50 % CH₃CN)
1. Galacturonic acid
2. Oligogalacturonic acid dimer
3. Oligogalacturonic acid trimer
4. Oligogalacturonic acid tetramer
5. Oligogalacturonic acid pentamer
6. Oligogalacturonic acid hexamer
7. Oligogalacturonic acid heptamer
8. Oligogalacturonic acid octamer
9. Oligogalacturonic acid nonamer
10. Oligogalacturonic acid decamer
11. Oligogalacturonic acid undecamer

Column       : Shodex HILICpak VN-50 4D (4.6 mm I.D. x 150 mm)
Eluent       : (A); 1 % HCOOH aq., (B); CH3CN   
              Linear gradient; (B %) 55 to 35 % (0 to 10 min), 35 % (10 to 15 min)
Flow rate    : 0.6 mL/min
Detector     : ELS
Column temp. : 40 °C