Optimization of ultrafiltration/diafiltration processes for partially bound impurities.

Area of Science:

• Biochemical Engineering
• Separation Science
• Process Optimization

Background:

• Ultrafiltration and diafiltration (UF/DF) are crucial for purifying biological products.
• The impact of impurity-product binding on UF/DF efficiency has not been experimentally or theoretically analyzed.

Purpose of the Study:

• To investigate the effect of equilibrium binding between impurities and products on impurity removal rates during UF/DF.
• To develop models and experimental validation for optimizing UF/DF processes in the presence of binding interactions.

Main Methods:

• Performed model calculations to simulate impurity clearance considering equilibrium binding.
• Conducted experiments using D-tryptophan (impurity) and bovine serum albumin (product) as a model system.

Main Results:

• Binding interactions significantly reduce the rate of small impurity removal.
• Increased numbers of diavolumes are required for effective impurity clearance when binding occurs.
• Optimal product concentration for diafiltration shifts to lower levels with stronger binding.

Conclusions:

• Product-impurity binding is a critical factor affecting UF/DF efficiency.
• Analytical expressions were developed to guide the design and optimization of industrial UF/DF processes.
• Understanding binding interactions is essential for efficient biological product purification.