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Assessment of Needs for Clarification

Assessing your needs is critical to obtaining the correct solution. Two areas to consider are: defining your process and determining the success criteria.

Defining Your Process

The first step of clarification process development is defining what your process must achieve, and what goals must be met. As part of the process, consider the following:
  • Where in the process are you clarifying?
  • What are you currently using for clarification? Do you use depth filters? A centrifuge? Do you have existing hardware?
  • What kind of reactor are you running? Perfusion, fed-batch, etc.?
  • Are there other process goals beyond fluid clarification? Impurity removal? Fluid conditioning?
Effectively defining your process will allow you to choose an appropriate unit operation and operating parameters. Process objectives to define are: feedstream characteristics, feed volume, and contaminant removal specification.

Process Objectives

Feedstream Characteristics
  • What kind of cell culture are you working with?
  • What is the cell density and viability?
  • What is the cell type?
  • Is the molecule of interest extracellular?
  • Is it homogenized or non-homogenized?
  • What is the nature of the protein (hydrophobic, protein stability, etc.)?
  • What type of protein are you working with (recombinant, etc.)?
  • What is the feedstream titer?
Feed Volume
  • Do you have capacity targets? Sterile filter capacity targets?
  • What scale are you planning?
  • Do you have a certain time in which the filtration must occur?
  • Do you have enough feed volume available for a wide media evaluation?
Pre-Use Sterilization or Sanitization
  • Do you have any requirements for sterility of the filters pre-use (low bioburden, sanitization)?
  • What comes next in your downstream operation? (extractables, sterile)

Determining Success Criteria

Once you’ve defined process objectives, you need to identify and quantify the criteria by which the success of the operation will be measured. The primary goals for successful protein processing are:
  • Clarity
  • Yield
  • Impurity removal
  • Capacity
  • Scale-up strategy
  • Processing time at full-scale operation

Success Criteria

Clarity objective It is important to understand any success criteria based upon the clarity of the effluent produced from the depth filter.
  • Will you monitor turbidity?
  • If sterile filtration is downstream of the secondary depth filtration step is there a minimum acceptable capacity on the sterile filter you must achieve?
  • Is there a minimum acceptable yield you must meet?
Impurity (DNA & HCP) Removal Some impurity removal has been noted utilizing depth filtration on some feed streams.
  • Will you monitor it?
  • At this stage, is it important to your process?
  • Are there minimum depth filter capacity requirements you must meet to fit depth filters into existing equipment?
Scale-Up Strategy
  • What is the next volume to which you will scale up?
  • Do you need good repeatability data at this point?
Ultimate Requirements for Processing Time at Full-Scale Operation
  • Is processing the molecule in question time sensitive?
  • Will you need to complete clarification of the feedstream within a certain amount of time?

Merck offers a full line of clarification products and services to help speed your biotech and plasma-derived products to market faster and more cost effectively.

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