This information is part of O2k-Open Support.
Biological contamination is caused by the growth of biological material (originating from samples or otherwise). It should not be confused with other kinds of chamber contamination mentioned in Cleaning the glass chamber.
Biological contamination of the chamber is typically characterized by a high O2 flux with a closed chamber near air saturation. It is detected by an Oxygen sensor test, an instrumental background test or by observing the flux at closed chamber for a short time routinely before any experiment. In the latter two cases the high flux contamination may be caused by biological contamination of the chamber itself or by a contaminated medium. This can be tested by observing the flux in pure water.
The ideal remedial agent is 70% ethanol with 30% water (not 100% ethanol). Make sure the 70% ethanol does not contain any additives. E.g. 70% ethanol used in hospital settings may contain antiseptics (information provided by Garcia-Roves PM). Prevention of biological contamination of the chamber is primarily by storage under 70% ethanol. If repeated washing with 70% Ethanol does not remove an existing biological contamination, the glass chamber has to be cleaned as described for protein contamination under Cleaning the glass chamber by removing the glass chamber from the instrument and using a strong acid.