Application of pH-Zone-Refining Countercurrent Chromatography in the Preparative Separation of Alkaloids from Traditional Chinese Medicine

pH-Zone-refining countercurrent chromatography (CCC) is a recently developed new preparative separation method based on conventional CCC. The method uses a retainer base (or acid) in the stationary phase to retain the analyses in the column and an eluent acid (or base) to elute the analyses according to their pKa values and hydrophobicities. It produces a succession of highly concentrated rectangular peaks with minimum overlap similar to those observed in displacement chromatography. pH-zone-refining CCC has important advantages over the conventional CCC including an over 10-fold increase (up to 10 gram or more) in sample loading capacity, high concentration of fractions, and concentration of minor impurities. pH-zone-refining CCC has been successfully applied to the preparative separation of a variety of compounds including both acidic and basic derivatives of amino acid, hydroxyxanthene dyes, peptides, alkaloids, indole auxins, structural, geometrial and optical isomers.