Study of the separation limits of continuous solid support free liquid–liquid chromatography: Separation of capsaicin and dihydrocapsaicin by centrifugal partition chromatography

Sequential centrifugal partition chromatography (sCPC) is a cyclic solid support-free liquid–liquid chromatographic process, in which a continuously introduced feed mixture is separated into two sequentially collected product streams. The few experimental demonstrations of this concept already revealed its potential for the preparative separation of pharmaceuticals and fine chemicals. In this work not only the possibilities, but also the limits of the sCPC technology are explored. A feed mixture consisting of capsaicin and dihydrocapsaicin, whose molecular structure differs in only one double bond, was selected for this purpose. The sCPC unit operating parameters needed for a complete separation of the feed mixture were selected using the recently published approach, which uses the partition coefficient of the feed components and the hydrodynamic characteristics of the system as input data. A complete separation of capsaicin and dihydrocapsaicin with the solvent system heptane/ethyl acetate/methanol/water:1/1/1/1 (v/v/v/v) was achieved, although the separation factor was only 1.32. The sCPC unit separation performance was successfully simulated using the cell model.

► Separation of a binary mixture with sequential centrifugal partition chromatography.
► Complete separation of a mixture with a separation factor of only 1.32.
► Short-cut method for the selection of sCPC unit operating parameters.
► Good agreement of sCPC simulation and experiment enables parametric studies.
► Higher productivity and lower solvent consumption than in stacked batch separation.