Sample displacement chromatography exploits the different relative binding affinities of components in a sample mixture to achieve accummulation of a desired substance on the column before elution. In pharmaceutical applications, requirements for purity and efficacy of plasmid DNA (pDNA) as a therapeutic product are stringent. The separation of linear, supercoiled (sc) and open-circular (oc) pDNA isoforms has already been established on CIM® butyl (C4 HLD) monolithic columns at preprative scale. This process requires high concentration of ammonium sulphate for loading which increases the overall production requirements. Competing adsorption in sample displacement chromatography utilises the binding capacity of the chromatographic resin more efficiently and increases productivity of the chromatographic step.
This application note investigates three monolithic chromatographic supports with different hydrophobicities regarding their applicability for sample displacement of pDNA. CIMac™ C4 HLD (butyl, high ligand density) as a commercial product and pyridine and histamine as custom immobilised columns are compared.