Degassing Media with Surfactants

Degassing media that contains surfactants can be difficult as the degassing process inevitably causes bubbles which will create a significant amount of foam. This foam can interfere with volumetric measurements and will also attach to the basket as it is placed into the media. There are three popular procedures that can be used:

1. The best method is to use a tank or a degasser where the media is withdrawn from the bottom. In this way all the foam remains at the top of the liquid and is not transferred to the vessels.
2. It is possible to blow the foam off with a gentle stream of air. This method should be done before the media is transferred to the vessel so that it does not affect the volume.
3. If you don't have the ability to do that, a couple of drops of methanol or ethyl ether can be used. The solvent should only be used if it is allowed within your internal SOPs.