Analysis of complex protein elution behavior in preparative ion exchange processes using a colloidal particle...

Area of Science:

• Biochemistry
• Chemical Engineering
• Chromatography

Background:

• Protein retention in preparative ion exchange (IEX) chromatography is crucial for model-based process development.
• The steric mass action (SMA) model has dominated mechanistic descriptions for 30 years.
• Recent preparative processes show protein retention profiles inconsistent with the SMA model.

Purpose of the Study:

• To analyze complex protein elution behavior in preparative IEX processes.
• To introduce and validate the colloidal particle adsorption (CPA) model for IEX chromatography.
• To demonstrate the CPA model's applicability to industrial case studies.

Main Methods:

• Analysis of complex protein elution using the colloidal particle adsorption (CPA) model.
• Comparison of CPA model predictions with traditional steric mass action (SMA) model.
• Validation using industrial case studies with monoclonal antibodies and various IEX systems.
• Investigation of both salt-controlled and pH-controlled protein elution.

Main Results:

• The CPA model successfully reproduces elution profiles unexplainable by the SMA model.
• Complex behavior is attributed to elution front compression and concentration in unsaturated column regions.
• Exceeding critical load density can cause peak front shoulders, as predicted by CPA.
• The CPA model demonstrates general applicability across different IEX systems and elution modes.

Conclusions:

• The CPA model offers a more accurate mechanistic understanding of protein retention in preparative IEX chromatography.
• This improved understanding facilitates more robust model-based process development.
• The CPA model provides valuable insights into phenomena like peak front compression and shoulder formation.