Observations of established dual flow in a spiral dual-flow counter-current chromatography coil.

This paper describes the observations made in dual-flow counter-current chromatography. For the first time, the behaviour of the phases inside a spiral dual-flow coil has been studied using stroboscopic visualisation. During the study it was observed that the phase distribution and the linear flow rate in the tubing were not uniform throughout the coil, but behaved differently at each end of the coil with a transition area in between. The location of the transition area is dependent on the flow rate of both the upper and the lower phase. Understanding and then explaining such counter-current flow will significantly help in the prediction of elution behaviour in true moving bed chromatography.