Effect of foaming power and foam stability on continuous concentration with foam counter-current chromatography

In order to facilitate the application of the foam counter-current chromatography (CCC) technique to various natural products, we have introduced two parameters, i.e., "foaming power" and "foam stability", which reliably indicate applicability of the sample to foam CCC. In each test, the sample was delivered into a graduated cylinder with a ground stopper followed by vigorous shaking. The foaming power was expressed by the volume ratio of the resulting foam to the remaining solution, and the foam stability by the duration of the foam. A set of data obtained from various samples including bacitracin, gardenia yellow, phloxine B, rose bengale and senega methanol extract revealed a significant correlation between these parameters and the degree of foam enrichment by foam CCC. The overall results indicated that a sample with the following properties may be effectively enriched by foam CCC: the foaming power is greater than 1.0 and the foam stability is over 250 min. We applied these experimental results to the enrichment of microcystins in a cyanobacteria bloom sample extract using foam CCC. (C) 1997 Elsevier Science B.V.