172 nm Photochemical Destruction of Three Commonly Used Anesthetic Gases with High Global Warming Potentials: Ultraviolet Absorption Spectra, Quantum Yields, and Product Analysis for Isoflurane, Desflurane, and Sevoflurane

Using chamber and UV/infrared spectroscopy techniques, the quantum yields and photolysis products of 172 nm radiation were determined for three commonly used anesthetic gases (isoflurane, desflurane, and sevoflurane). Vacuum UV spectra were recorded, and the 172 nm cross sections measured to be σ172 nm(CF3CClHOCF2H) = 3.08 × 10–19, σ172 nm(CF3CFHOCF2H) = 1.83 × 10–20, and σ172 nm((CF3)2HCOCFH2) = 3.20 × 10–20 cm2 molecule–1. Kinetics experiments were conducted in 700 Torr of N2 diluent at 295 ± 2 K with dimethyl ether used as an actinometer. A value of σ172 nm(CH3OCH3) = 3.13 × 10–18 cm2 molecule–1 was determined as part of this study. The photolysis rate experiments gave relative rates of Jsevoflurane/JDME = 0.010 ± 0.002, Jisoflurane/Jsevoflurane = 0.80 ± 0.01, and Jdesflurane/Jsevoflurane = 0.18 ± 0.05. The resulting 172 nm quantum yields for isoflurane, desflurane, and sevoflurane were 0.08 ± 0.02, 0.32 ± 0.07, and 1.01 ± 0.20, respectively. Major photolysis products observed were CO, COF2, HCOF, and CF3C(O)CF3. The results are discussed in relation to photochemical air pollution abatement.