Elution-extrusion and back-extrusion counter-current chromatography using three-phase solvent system for separation of organic dye mixture

In the present study, high-speed counter-current chromatography with a three-phase solvent system composed of n -hexane-acetonitrile-400 mM ammonium sulfate (1:1:1, v/v) was developed to recover four mixed dyes (methyl green, acridine orange, Congo red and oil red O) with diverse polarities. As a result, four dyes were successfully separated in a single HSCCC run using a step-wise gradient elution. Then, elution-extrusion and back-extrusion counter-current chromatography were used to reduce the separation time and solvent consumption. Among them back-extrusion CCC can save more time. Thus, the present study provides an effective method for dye recycling.