Expanded bed chromatography of proteins in small diameter columns. I. Scale down and validation.

The use of large columns for expanded-bed chromatography in protein adsorption and purification can pose limitations in method scouting due to the high volumes of consumables involved in optimisation runs. Scaling down this technique would provide a practical and necessary first step for demonstrating its feasibility in very small beds. The performance of three columns of diameters 5.0, 1.0 and 0.5 cm were compared in terms of the bed expansion, hydrodynamics and breakthrough for lysozyme adsorption onto STREAMLINE-SP. This represented a scale-down factor of a 100-fold from the 5-cm column and the success was judged by the insignificant changes in performance based on the selected criteria. Bed characterisation and breakthrough runs indicated good plug flow behaviour, despite the high particle size to column diameter ratio in the smaller columns. The column efficiency was found to be sensitive to the vertical alignment, making it an important issue in scale down. The results of these investigations show that small diameter columns can be effectively used for mimicking the behaviour in scale up systems providing a useful tool for method scouting studies.