Cross-Axis Synchronous Flow-Through Coil Planet Centrifuge Free of Rotary Seals for Preparative Countercurrent Chromatography. Part II. Studies on Phase Distribution and Partition Efficiency in Coaxial Coils

Abstract Potential capability of the apparatus in performing countercurrent chroma-tography has been examined with three different types of coiled columns, all coaxially mounted around the holder. In single-layer coils, typical solvent systems display characteristic hydrodynamic distribution which ensures a stable retention of the stationary phase against heavy sample loading in preparative separations. Direct observation of the hydrodynamic motion in the rotating spiral column revealed vigorous mixing of the two solvent phases throughout the area which promises a high partition efficiency of the present method. Gram-quantity preparative separations were performed in the multilayer coil with two different sets of test samples: Isocratic elution of dinitrophenyl amino acids yielded high partition efficiency of 1600 theoretical plates while the versatility of the method was demonstrated on gradient elution of dipeptides including two pairs of sequential isomers.