Separation of five isomers of dihydroxybenzoic acid by high-speed counter-current chromatography with dual-rotation elution method

Abstract

Five small molecular isomers, 2,3-, 2,4-, 2,6-, 3,4-, and 3,5- dihydroxybenzoic acid, were successfully separated in one step with solvent system n-hexane-ethyl acetate-methanol-water (1:5:1.5:5) on high-speed counter-current chromatography (HSCCC). A new method, dual-rotation elution, was successfully used to decrease separation time and increase resolution. Five peak factions were eluted within 850 min. HSCCC became an efficient method to separate small molecular isomers from intermediates and products of organic synthesis, especially with the dual-rotation elution method.