Recycling foam countercurrent chromatography
A new sample injection method for foam countercurrent chromatography (CCC), named the "recycle injection system", has been developed. In this system, the effluent from the liquid outlet is directly returned into the column through the sample feed line so that the sample solution is continuously recycled for repetitive foam fractionation. The utility of this system was demonstrated in the separations of microcystin extract and bacitracin complex from large volumes of sample solution. Microcystins were separated and enriched in decreasing order of hydrophobicity. Bacitracin A, a hydrophobic major component, in the bacitracin complex was highly enriched in the foam fraction and almost completely isolated from other components. This recycling foam CCC method may be effectively applied for separation and enrichment of various foam-active components from crude natural products.