Foam counter-current chromatography with the cross-axis synchronous flow-through coil planet centrifuge.

A novel coil planet centrifuge system performs efficient foam separation in a long multilayer coil. Potential capability of the method was successfully demonstrated in separations of two sets of test samples using sodium dodecyl sulfate as a foaming agent. Rhodamine B with high foam affinity was quickly separated from Evans blue lacking foam affinity. A high concentration of salts such as disodium hydrogenphosphate in the surfactant solution effectively lowered the foam affinity of basic dyes, yielding complete peak resolution of rhodamine B and methylene blue according to a subtle difference in foam affinity.