Negative gradient slope methods to improve the separation of closely eluting proteins

Area of Science:

• Analytical Chemistry
• Biopharmaceutical Analysis
• Chromatography

Background:

• Separating closely eluting peaks in therapeutic protein samples is crucial for quality control.
• Existing methods may struggle with resolving critical peak pairs, impacting analytical accuracy.

Purpose of the Study:

• To introduce and validate a new chromatographic strategy for enhanced resolution of challenging protein separations.
• To demonstrate the practical advantages of using multiple isocratic steps with a negative gradient segment.

Main Methods:

• Computational modeling of retention parameters (logk0 and S) for model systems.
• Application of the multi-isocratic strategy with a negative gradient in two real-world biopharmaceutical analyses.
• Utilizing reversed-phase liquid chromatography (RPLC) for protein separation.

Main Results:

• Model calculations confirmed the potential of the negative gradient approach for improving selectivity.
• Successful separation of a therapeutic monoclonal antibody (mAb) from its closely eluting variant.
• Effective separation of a carrier protein from an intact mAb in a quantitative bioanalysis context.

Conclusions:

• The strategy of incorporating a negative gradient segment into multi-isocratic elution programs is effective for improving selectivity in protein RPLC.
• This approach is particularly useful for large solutes exhibiting 'on-off' elution behavior.
• The method provides practical advantages for resolving critical peak pairs in biopharmaceutical analysis.