FOAM COUNTERCURRENT CHROMATOGRAPHY OF BACITRACIN .2. CONTINUOUS REMOVAL AND CONCENTRATION OF HYDROPHOBIC COMPONENTS WITH NITROGEN GAS AND DISTILLED WATER FREE OF SURFACTANTS OR OTHER ADDITIVES

Foam counter-current chromatography has been successfully applied to continuous removal and concentration of hydrophobic bacitracin (BC) components from a large volume solution using nitrogen gas and distilled water free of surfactants or other additives. The experiment was initiated by introducing nitrogen at the head inlet of the coil rotated at 500 rpm. Then, a 2.5-1 volume of the sample solution containing BC at 50 ppm was continuously introduced into the middle portion of the coil at 1.5 ml/min. The hydrophobic components produced a thick foam which was carried with the gas phase and collected from the tail end of the coil while other components stayed in the liquid stream and eluted from the head outlet of the coil. High-performance liquid chromatographic analysis of the foam fraction revealed that the degree of enrichment increased with hydrophobicity of the BC components. BC-A and -F were enriched 1400 and 2260 times, respectively, compared with the original concentration in the sample solution. These results clearly indicate that the present method will be quite effective for detection and/or isolation of a small amount of natural products present in a large volume of aqueous solution.