Dispersed mobile-phase countercurrent chromatography

Abstract

A dispersed mobile-phase countercurrent chromatography system is described in which solutes are carried by a stream of dispersed mobile phase solvent through a column, or array of serially-connected columns, of stationary phase solvent with which the mobile phase solvent is immiscible. Solutes carried along by the stream of dispersed mobile-phase solvent will be equilibrated between the mobile-phase solvent and the stationary-phase solvent. Because the mobile-phase is dispersed into mini-droplets much smaller in diameter than the column of stationary phase, the enhanced surface/volume ratio of the droplets expedites countercurrent equilibration of different solutes between the mobile-phase solvent and the stationary-phase solvent in accordance with the distribution-coefficients of the solutes between the two solvents. As a result, a solute with a distribution coefficient that favors its dissolving in the stationary phase will be retarded in its migration through the columns compared to a solute with a distribution coefficient that favors its dissolving in the mobile phase. The different migration rates of different solutes bring about their chromatographic separation on the columns, effectively combining the advantages of countercurrent distribution (e.g., elimination of any solid chromatographic matrix, and therefore losses of solutes due to adsorption to the solid matrix and contamination of separated solutes by impurities leached from the solid matrix) and liquid column chromatography (e.g., continuous mode of operation, and scalable from analytical to large industrial separations without any centrifugal or discontinuous mechanical steps).