ACETONE CHEMICAL-IONIZATION MASS-SPECTROMETRY

Chemical ionization mass spectrometry (CIMS) is often used for the cha racterization of thermally stable and electron impact-labile compounds , and acetone is one of the CI reagent gases used not only to characte rize the analytes but also to differentiate regio-and stereoisomers. T he nature of the reagent ions, the factors affecting the reagent plasm a, and the type of ion-molecule reactions with the substrate molecules under acetone/CI are briefly discussed in this article. The ion-molec ule reactions between the reagent ions and a wide variety of organic c ompounds are reviewed. The mechanisms involved in the formation of cha racteristic ions studied by using acetone-d(6) as a reagent and also b y collision-induced dissociation of the respective adduct ions have be en discussed. The site of acetylation in most of the substrates by the reagent ions of acetone has been found to depend on the nature and po sition of the substituents present in the substrate, and in some cases the acetylation reaction is controlled by the steric factors. (C) 199 8 John Wiley & Sons, Inc.