Fractionation of apple procyanidins by size-exclusion chromatography

Oligomeric constituents of apple procyanidins were fractionated by size-exc lusion chromatography using a TSKgel Toyopearl HW-40F column. The best sepa ration was obtained using a mobile phase of acetone-8 M urea (6:4; adjusted to pH 2) at a flow-rate of 1.0 ml/min. In this chromatographic system, the use of 8 M urea in the mobile phase resulted in a molecular sieve effect w ithout any surface affinity interaction between the gel beads and the procy anidin molecules. Each fraction obtained was examined by reversed-phase hig h-performance liquid chromatography and time-of-flight mass spectrometry. T he order of elution of the procyanidins from the column was coincident with their degree of polymerization. (C) 1999 Elsevier Science B.V. All rights reserved.