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Results: Continuous diafiltration using stirred cells requires fewer diafiltration volumes for equivalent salt reduction.
Table: Conductivity measurements, corresponding salt concentration and % salt reduction after each diafiltration volume, for discontinuous diafiltration and continuous diafiltration.
Discontinuous and Continuous Diafiltration Conclusion
Our results show that continuous diafiltration using the Amicon® Stirred Cells enables more efficient buffer exchange with less diafiltration volumes to reach 99% salt reduction compared to discontinuous diafiltration. Furthermore, in continuous mode, the stirred cell does not have to be disassembled between each diafiltration volume.
During continuous diafiltration, the protein concentration stayed constant at 1 mg/mL throughout the process, while in discontinuous diafiltration, the protein concentration fluctuated significantly between 1 mg/mL and 0.5 mg/mL. Therefore, continuous diafiltration is much more gentler than discontinuous diafiltration, as it maintains product stability by keeping the sample concentration and volume constant during diafiltration.
The flexible, easy-to-use Amicon® Stirred Cells are compatible with a broad range of process volumes (up to 400 mL) that can be further expanded with an addition of an external reservoir, which can be used for large volume concentration as well as batch and constant-volume diafiltration.
The new design of the Amicon® Stirred Cells accommodates a wide range of ultrafiltration and microfiltration disc membranes, which can be used to optimize concentration and diafiltration conditions. Unlike centrifugal devices, the pressure-based format provides a gentler method for concentration, reducing the likelihood of shear stress-induced denaturation.
Further, the inclusion of magnetic stirring at the filtration interface greatly minimizes the risk of concentration polarization and fouling.