Orthogonality in the selection of biphasic solvent systems for off-line two-dimensional countercurrent chromatography from Polygonum cuspidatum Sieb. et Zucc

•Orthogonality in selection of biphasic solvent systems was evaluated.•The dendrogram and colour map was used to show the dissimilarity for solvent systems.•The space occupancy rate was evaluated by convex hull method.•Efficiency of liquid-liquid chromatography separation was enhanced.•Complete separation of the different extracts from Polygonum cuspidatum was achieved.