Impurities in halothane: their identities, concentrations and determination

Abstract

The following impurities arising during the manufacture of a proprietary halothane have been identified by gas chromatographic, mass spectrometric, nmr and infrared techniques: 2‐chloro‐, 2,2‐dichloro‐, 2‐bromo‐, 2,2‐dibromo‐, 2,2‐dibromo‐2‐chloro‐ and 2‐bromo‐2,2‐dichloro‐1,1,1‐trifluoroethanes, 1,1,2‐trichloro‐1,2,2‐trifluoroethane, 1,2‐dichloro‐1,1‐difluoroethane, 2‐bromo‐2‐chloro‐1,1‐difluoroethylene, bromodichlorofluoromethane, chloroform, trans‐2‐bromo‐1,1,1,4,4,4‐hexafluorobut‐2‐ene and the trans and cis isomers of 2‐chloro‐ and 2,3‐dichloro‐1,1,1,4,4,4‐hexafluorobut‐2‐enes. Gas chromatographic methods using chlorinated biphenyl, dinonyl phthalate and polyethylene glycol as liquid phases have been developed for their determination at the ppm level.