Polyphenols in countercurrent chromatography.An example of large scale separation

Polyphenols are sometimes difficult to separate in classical liquid chromatography. Countercurrent chromatography uses a biphasic liquid system to separate the components of a mixture. A centrifugal field allows to use a liquid stationary phase in an open tube. The phase density difference and the centrifugal field are the only parameters allowing the equilibrium between the two liquid phases. The big advantage of the technique in preparative separation is the dual-mode capability of CCC. The role of the phases can be switched during a run. The mobile phase becomes stationary and vice versa. Then no injected material can be left in the machine. The large scale separations of a flavonoid mixture and two tannin samples are described: choice of the biphasic liquid system, analytical study, scaling-up, injection protocol, two step separation in case of dual-mode use. It was possible to inject 26 g of a tannin sample in one run.