Reducing Holdup Volume in Sterile Filtration 

All filters rely on some level of gravity to move liquids through them, but gravity isn’t enough on its own. The internal flow path design of a filter has an impact on how efficiently and effectively fluid moves through it. Any remaining material that is trapped is known as “holdup volume.” This material is trapped in a pocket or otherwise cannot be expelled from the filter.

Each drop of material  stuck inside a filter represents lost product that can’t be sold or used. Therefore, minimizing hold up volume can significantly reduce your cost of doing business.

When to Evaluate Holdup Volumes

Products like stem cells, gene therapies, and new mRNA vaccines are both difficult and expensive to produce in large volumes. Even a relatively small amount of material trapped in a filter may be worth a significant portion of your investment. This material could be part of a dose that defeats a rare form of cancer, or it could represent a sample that could unlock new secrets of the human genome.

Because of this, it can be very important to minimize hold-up volume when choosing a system design – the earlier the better. The process choices you make at the lab or pilot phase are often reflected during scale-up, which means that your hold-up volumes may be somewhat baked in. Those valuable milliliters of fluid at lab scale might turn into much larger and more expensive volumes at commercial scale.

Finally, holdup volume  makes its biggest financial impact during final fill. Here, your active ingredients are most concentrated, and your process has the most time and money invested.

How Does Specific Filtration Geometry Affect Holdup Volumes?

Two filters can have the same membrane surface area, but they can also have different holdup volumes due to capsule configuration. The flow paths of each filter design are unique and take material on unique pathways as they remove contaminants.

Watch our recent video from Senior Field Applications Engineer Chris Rios for more insights on reducing holdup volume. For even more answers, download our eBook and receive a complete guide to life sciences filtration. 

Watch Chris Rios share ways to limit lost product in filters.

To design the contamination control solution that’s best for your process, please contact our team for an evaluation of your target contaminants and manufacturing conditions.