Foam counter-current chromatography of bacitracin. I. Batch separation with nitrogen and water free of additives.

A foam counter-current chromatographic method utilizing a true counter-current movement between nitrogen and distilled water through a long narrow coiled tube is described. Samples introduced into the coil are separated according to their foaming capability: foam-active materials generate foam and quickly move with nitrogen toward one end of the coil while the remainder are carried with the liquid stream in the opposite direction and eluted through the other end of the coil. The utility of the method was demonstrated in the fractionation of commercial bacitracin (BC). Hydrophobic components including BC-A, BC-F and several minor components were enriched with foam and collected in decreasing order of hydrophobicity, whereas hydrophilic components were eluted with the liquid in decreasing order of polarity. The results indicate that foam-active components can be effectively separated by foam counter-current chromatography using nitrogen and distilled water without a surfactant or other additives.