Large-scale preparative countercurrent chromatography for separation of polar compounds

Gram quantity separations of polar compounds (tryptophyl-leucine and valyl-tyrosine) have successfully been accomplished with the use of a horizontal coil planet centrifuge. Two columns of different length fluorinated ethylene propylene tubing but of same internal diameter (0.55 cm) were coaxially coiled around a holder 7.5 cm or 15 cm in diameter and used to assess the preparative capabilities of the apparatus in terms of stationary phase retention and sample peak resolution. Optimal operating conditions derived from preliminary studies with the short column were applied to a column 7 times in length and volume. Volume capacities were 114 ml and 750 ml respectively. A hydrophilic solvent system of n-butanol, acetic acid and water (4:1:5) was used with both the aqueous and non-aqueous phases being used as the mobile phase. Preliminary studies revealed that the hydrodynamic distribution of the two phases was independent of the helical diameter while peak resolution was sensitive to both helical diameter and rpm setting.