Separation and Purification with a Liquid Stationary Phase

Yoichiro Ito introduced countercurrent chromatography (CCC) in 1966, reporting the separation of blood plasma cells with a sealed helical tube. Since then, CCC has been a fertile ground for instrumental and technical innovation. The key innovation of CCC was to use centrifugal forces to retain the stationary liquid phase in the column in such a way that it is able to interact dynamically with the mobile phase without any solid support. The broad diversity of countercurrent separation terminology reflects the innovative spirit of the field, as well as the global appeal of this technique. The selection of the appropriate biphasic liquid system is the core of the CCC technique. The CCC columns must generate the centrifugal field needed to maintain the liquid stationary phase; therefore, they cannot be a simple tube with frits at both ends. Rotors, motor, gears, spools, and rotating seals are very specific things that are not needed in a classical liquid chromatography column with a solid stationary phase. The differences between the two main types of CCC columns are described. The bases of the CCC theory are also given.