Polyphenols in countercurrent chromatography. An example of large scale separation

Polyphenols are sometimes difficult to separate in classical liquid chromat ography. Countercurrent chromatography uses a biphasic liquid system to sep arate the components of a mixture. A centrifugal field allows to use a liqu id stationary phase in an open tube. The phase density difference and the c entrifugal field are the only parameters allowing the equilibrium between t he two liquid phases. The big advantage of the technique in preparative sep aration is the dual-mode capability of CCC. The role of the phases can be s witched during a run. The mobile phase becomes stationary and vice versa. T hen no injected material can be left in the machine. The large scale separa tions of a flavonoid mixture and two tannin samples are described: choice o f the biphasic liquid system, analytical study, scaling-up, injection proto col, two step separation in case of dual-mode use. It was possible to injec t 26 g of a tannin sample in one run.