Centrifugal Partition Chromatography. II. Selectivity Efficiency

Abstract

Centrifugal Partition Chromatography (CPC) is a technique that uses two immiscible liquids. One liquid is used as a stationary phase, the second one as the mobile phase. Using the liquid systems methanol-hexane and octanol-water, the selectivity and efficiency of CPC apparatus were tested. It is shown that CPC can be used to determine partition coefficients or to purify compounds. The selectivity can be changed the same way as in liquid chromatography. The efficiency study has shown that the plate count presents a minimum value at a particular flow rate. By plotting the number of channels required to obtain one theoretical plate versus the flow rate, it is possible to obtain a “van Deemter-type” plot. Interestingly, these plots show maxima for CPC. These results are opposite to those found for liquid or gas chromatography which have minima. A flow change, from laminar to nonlaminar is thought to explain these results. Reynolds numbers were determined for all solvent systems. Efficiency in CPC was also found to be solute dependent: the larger the partition coefficient, the lower the efficiency.