Assessment of Needs
for Ultrafiltration

• Where in the process is the ultrafiltration step?
• What molecular weight cut-off membranes have you evaluated?
• What membrane types (materials of construction) have you evaluated?
• What are your feed stream and buffer conditions (concentration, pH and/or conductivity)?
• Do you have any process limitations (time, floor space, temperature etc.) to consider?
• How will you define success (product quality, yield etc)?

Select Unit Operation and Operating Parameters

Once you understand your objectives, you can select an appropriate unit operation and operating parameters. Important process objectives and questions to help define them are:

• Final product concentration: What is your final concentration requirement?
• Feed volume reduction: What is your final volume requirement?
• Extent of buffer exchange: What are your final pH, conductivity or buffer specifications?
• Contaminant removal specification: Do you have specifications on residual contaminants?

Specify Success Criteria

Next, identify and quantify any criteria by which you will measure the operation’s success. Your goal(s) should be your guide. Primary goals for successful protein processing are typically:

• High product yield
• High product quality (or activity, aggregation, oxidation)
• High product purity
• Process consistency and robustness (lot-to-lot variability and re-use)

In addition, the process should scale up accurately, enable straightforward validation and be robust during continued use at industrial scale.

Finally, you’ll want to ensure that you meet the economic objectives for the process as well as observe any constraints (for example, process time, unit operation size or buffer use).

Contact the Ultrafiltration Team to explore how we can help you avoid costly errors by verifying that your design falls within Merck's guidelines (actual process performance to be verified with optimization and process simulation trials).