Oxygen leakage during respirometric measurements: A caution on the use of PTFE tape

Oxygen leakage occurred during studies using respirometers that were supposed to be sealed. The leakage occurred around rubber stoppers inserted through the wall of the respirometric vessel and was caused by PTFE tape that was wrapped around the stoppers. Rewrapping the stoppers so that the tape did not extend between the stopper and the glass of the vessel eliminated the problem.