Modelling gradient elution in centrifugal partition chromatography

Varying the phase composition of a multi-component two-phase system during a centrifugal partition chromatography (CPC) separation leads to additional degrees of freedom to influence the separation efficiency and total separation time. Optimisation of a CPC (gradient) separation is a difficult task due to the large number of two-phase systems and the different elution modes that can be applied. A model is presented that predicts effluent concentration profiles of gradient elution, given the partition coefficients of the components and a mass transfer relationship as a function of the local phase composition, at a fixed flow-rate, stationary phase hold-up and rotational frequency. The model is verified by comparing the results of simulated effluent concentration profiles to experimental effluent concentration profiles. It is shown how the composition-dependent parameters needed for the model predictions can be accessed experimentally. By performing model aided optimisation of CPC separations the time needed for optimising a gradient elution, and the need for laborious experimental work is reduced significantly.