Separation of Apple Catechin Oligomers by CCC

Catechin oligomers with different degrees of polymerization were separated from apple condensed tannins (ACTs) by countercurrent chromatography using a type‐J multilayer coil planet centrifuge. Partition coefficient values for oligomers up to pentamers of catechin and/or epicatechin were determined on hydrophilic two‐ or three‐phase solvent systems. The best separation was achieved using a three‐phase solvent system composed of hexane/methyl acetate/acetonitrile/water at a volume ratio of 1/1/1/1, which formed three layers. After the elution of monomers, dimers, trimers, and a part of tetramers using the middle phase, methyl acetate was used as a mobile phase to facilitate elution of the oligomers from tetramers to decamers. These oligomers eluted from the column according to their degree of polymerization. The higher polymerized oligomers over 11‐mers were collected from the column with the elution by the lower phase. The masses of the fractionated oligomers were determined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis using 2′,4′,6′‐trihydroxy acetophenone monohydrate as a matrix.