Abstract: The ratio between length and diameter of the column and the velocity of flow which influence the isolation of theapple polyphenols have been studied in this paper. According to three targets such as ratio of desorption, isolation ratio ofepicatechin and chlorogenic acid ,we compared the two parameters to determine the best condition of the isolation. We adopteda Sephadex LH-20 column to isolate the apple polyphenols and the mobile phase is ethanol in deionized water and 60% acetonein deionized water. The data indicate that the three targets are the best when the velocity of adsorption is 1.5ml/min, the velocityof desorption is 1.0ml/min and the ratio of the column is 20×2.5.

Key words: apple polyphenols, isolation, purification, Sephadex LH-20