Autoclaving Contaminated Liquids: No Problem?

In many research and diagnostic facilities, liters of biologically contaminated liquid waste are produced on a daily basis and need to be safely disposed of. The gold standard is steam sterilization, namely, in most cases autoclaving for 20 minutes at 121°C. Here we demonstrate the importance of the following parameters when autoclaving liquid waste solutions in a laboratory setting: (1) size of the receptacle for the reference probe, (2) material of the vessel containing the liquid to be autoclaved, and (3) volume of the liquid in the receptacle. If not appropriately controlled, the temperature required to inactivate the liquid might never be reached at all, thus representing a biohazard that should not be underestimated. Our results demonstrate that it is critical to use identical receptacles and liquid volumes for the temperature reference probe and for the liquid to be autoclaved