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Choosing Syringe Filters

This page previously recommended PVDF filters. Do not use these. After further research we discovered that we received a bad recommendation. There is insufficient data about the interactions between benzyl benzoate and PDVF. Combining BB with PDVF may result in filter degradation and failure. Instead use PTFE filters. PTFE has studied compatibility with BA, BB, and organically derived oils.

  • Pore Size: 0.22μm (this size is required for sterilization)
  • Sterility: Use pre-packaged, sterile filters.
  • Size: if you’re filtering 1-10mL, use a 13mm filter. 10-100mL use a 25mm filter.1 100m-250mL use a 33mm filter.2 Keep in mind that the filter will eat some of your final product. The larger the filter the more product it will retain. At the same time, a larger filter will be easier to push your preparation through.
  • Filter material: Hydrophilic Polytetrafluoroethylene (PTFE) is moderately available and is compatible with our goals. It is safe with oil, benzyl alcohol, and benzyl benzoate.3 4

Make sure the filters you are purchasing list a bubble point on them. We need to do a bubble point test after terminal sterilization to ensure that the filter kept its integrity. We’ve seen it also listed as “Max Burst Pressure.” You can also preform a test on a spare filter to find the bubble point yourself.

More compatibility charts: