UV-based solvent system screening for high-speed counter-current chromatography fractionation of compounds with similar UV absorption from complex samples followed by preparative HPLC purification: Flavonoids from barley seedlings as sample.

This article proposes a solvent system screening strategy for compounds with similar UV absorption in complex samples by UV spectrophotometer. There is no need to calculate the partition coefficient value of each compound, only the partition coefficient of the whole sample. The partition coefficient value should be close to 1 in order to obtain as many high-speed counter-current chromatography fractions as possible. Then, preparative HPLC was used to purify the high-speed counter-current chromatography fractions. Based on the above strategy, seven c-glycosyl flavonoids and an amino acid were successfully obtained from barley seedlings through high-speed counter-current chromatography fractionation with ethyl acetate/n-butanol/water (8:2:10, v:v:v) system followed by preparative HPLC purification. The research shows that high-speed counter-current chromatography could be well developed as a tool for fractionation before purification, and greatly improves the separation efficiency.