OPTIMIZATION OF COUNTERCURRENT CHROMATOGRAPHY SOLVENT SYSTEMS

Countercurent chromatography (CCC) provides a high resolution, complementary technique to adsorption chromatography for the preparative separation of complex mixtures. The capacity of CCC to achieve a desired separation is greatly enhanced by the use of a solvent system which adequately retains the components of interest but allows their elution without excessive amounts of mobile phase. The most direct approach for selecting such a solvent system involves finding and modifying an appropriate system until the components of interest display partition coefficients (PC's) between 0.67 and 1.5. PC's are readily estimated by partitioning aliquots in small but equal volumes of the pre-equilibrated phases of biphasic systems of differing polarities and then estimating the amount of the components in each phase by such techniques as TLC densitometry or HPLC. Suggestions and examples of finding appropriate solvent systems are discussed.