Separation of two constituents from purple sweet potato by combination of silica gel column and high-speed counter-current chromatography

► A thin layer chromatograph coupling with fluorometric (TLC-F) method for selecting HSCCC solvent system was proposed. ► 6,7-Dimethoxycoumarin and 5-hydroxymethyl-2-furfural were successfully separated from purple sweet potato extracts by successive sample injection for the first time. ► The results of our study suggested that the TLC-F method is useful to select HSCCC solvent systems. It is known that the choice of solvent system for high speed counter-current chromatography separation is of utmost importance. In this study, a simple and rapid thin layer chromatograph coupling with fluorometric (TLC-F) method has been used to determine the partition coefficient of target compounds in HSCCC solvent system. Two components, 6,7-dimethoxycoumarin and 5-hydroxymethyl-2-furfural were successfully separated from purple sweet potato extracts by successive sample injection for the first time, using n-hexane–ethyl acetate–methanol–water (1:2:1:1, v/v/v/v) as the solvent system. Additionally, statistical analysis showed that there was no significant difference in partition coefficient obtained by the TLC-F method and by HPLC, which demonstrated the usefulness of TLC-F method.