GE Healthcare Life Sciences

In polishing the focus is almost entirely on high resolution to achieve final purity. Formulation of the bulk product for storage, and subsequent use can also influence your choice.

Most contaminants and impurities have already been removed except for trace amounts of leachables, endotoxins, nucleic acids or viruses. These contaminants can be removed whilst allowing the product to pass through (thus, anion exchange can be used to pick up trace amounts of DNA and endotoxins).

Closely related substances such as micro-heterogeneous structural variants of the product, and reagents or aggregates can still need removal. To achieve resolution use very small uniform beads and shallow gradients as well as highly selective media. It may be necessary to sacrifice sample load or even recovery (by peak cutting).

Recovery of the final product is also a high priority since product losses at this stage are more costly than in earlier stages. Ideally the product should be recovered in buffer ready for the next procedure.

Polishing Problem
Technique

IEC

HIC

High ionic strength, intermediate step was IEC

Yes,
ideally use small bead media (HP or SOURCE-based), if necessary condition sample using diafiltration/ultrafiltration

Yes,
if product binds to HIC media (HP or SOURCE 15)

Yes,
if small sample volume and dilution can be accepted (preferably Superdex or Sephacryl)

Low ionic strength, intermediate step was HIC

Yes,
using HP or SOURCE 15 media

Avoid,
or use HP or SOURCE 15 media only

Yes,
if small sample volume and dilution can be accepted (preferably Superdex or Sephacryl)

Final DNA/endotoxin removal

Yes,
anion exchanger, using HP or SOURCE 15 media

Avoid,
or use HP or SOURCE 15 media only

Yes,
if small sample volume and dilution can be accepted (preferably Superdex or Sephacryl)

Contribution to final virus removal

Yes,
using HP or SOURCE 15 media

Yes,
use HP or SOURCE media

Yes,
if small sample volume and dilution can be accepted (preferably Superdex or Sephacryl)