Shallow bed adsorption:: Theoretical background and applications

The estimation of parameters for the design of chromatography columns at extremely small scale is required when the amount of feed stock or gel material is limited. The method of shallow bed adsorption, also known as zero length column or differential contactor allows the estimation of uptake kinetics and equilibria, at a scale of less than 100 mu L bed volume. The shallow bed is an infinite bath, which assumes that the liquid phase concentration does not change during the process of adsorption. This is achieved by keeping the volume of the stationary phase negligibly small so that the bound material does not influence the liquid phase concentration. Several examples are given to demonstrate the usefulness of this method and a protocol is suggested as to how it can be implemented in process development.