Structure identification of free radicals by ESR and GC/MS of PBN spin adducts from the in vitro and in vivo rat liver metabolism of halothane.

Free radicals were detected from the in vitro metabolism of halothane (rat liver microsomes) by the PBN spin trapping method. The detected radical species include the 1-chloro-2,2,2-trifluoro-1-ethyl radical (I), as determined by mass spectral analysis, and lipid-type radicals assigned by high resolution ESR spectroscopy with the use of d14-deuterated PBN. The lipid-derived radicals are a carbon-centred radical with the partially assigned structure CH2R and an oxygen-centred radical of the OR' type. From the mass spectral analysis of the spin adduct mixture there is also evidence for a halocarbon double adduct of PBN of the type I-PBN-I.