Sevoflurane degradation is accelerated by ozone: water trap removal of degradation products

Halogenated anesthetics such as sevoflurane have a high global warming potential (GWP) and should be degraded before atmospheric release. We hypothesized that sevoflurane undergoes oxidative degradation when mixed with ozone and some degradation products can be captured using a water trap.

In Experiment 1, sevoflurane and its degradation products were monitored in real-time using liquid chromatography-mass spectrometry under three conditions: air control, ozone mixing, and ozone mixing followed by passage through a water trap. In Experiment 2, sevoflurane (7-8%) was delivered into a closed anesthesia circuit, and concentration changes were recorded every 10 s under ozone-present and ozone-absent conditions (six trials each). In Experiment 3, proton nuclear magnetic resonance (¹H NMR, Bruker Ascend 400, 20.1°C) was performed on heavy-water samples from the water trap used in Experiment 2 to assess the solubility of ozone-exposed sevoflurane.

In Experiment 1, ozone accelerated sevoflurane degradation; however, the concentration of the degradation products was not increased in the water trap. In Experiment 2, ozone mixing caused a rapid decline in sevoflurane concentration, decreasing from 7.3% to < 1% within 25-28 s and reaching 0% within 265-288 s, whereas no decrease was found in the ozone-absent trials (P < 0.001). In Experiment 3, ¹H NMR spectra showed clearer sevoflurane signals and minor new peaks after ozone exposure, suggesting enhanced apparent solubility and limited decomposition.

Ozone mixing accelerated sevoflurane degradation and increased its water solubility, suggesting a practical approach for reducing the environmental impact of sevoflurane.