Dimethyl ether chemical ionization mass spectrometry

The uses of dimethyl ether (DME) as an unusual positive ion reagent for chemical ionization mass-spectrometry (CIMS) are reviewed. The fragment-molecule adducts formed by ion-molecule reactions of organic substrates with the ionized gas are highly characteristic for the substrates and frequently can be used to differentiate among isomers. The fragmentation mechanisms of the adducts have been studied by collision-induced dissociation and with deuterium labeling, and, in some cases, are well-understood. DME CIMS has been applied to a wide variety of classes of organic compounds, including substituted aromatics, amino alcohols, lactones, lactams, polyethylene glycols, benzodiazepines, azepines, trichothecenes, and certain alkaloids, nucleoside antibiotics, and polynuclear aromatic hydrocarbons. (C) 1995 John Wiley & Sons, Inc.