Determination of the double bond position in functionalized monoenes by chemical ionization ion-trap mass spectrometry using acetonitrile as a reagent gas

Acetonitrile may be used as a chemical ionization reagent gas in ion-trap m ass spectrometry for the location of double bonds in functionalized long-ch ain monoenes, [C3H4N](+): derived from acetonitrile, reacts with carbon-car bon double bonds, generating one or a pair of fragment tons characteristic of the position of the double bond in the chain. Tolerance of a range of fu nctional groups is achieved by isolating [C3H4N](+) from the other acetonit rile ions before reaction with the alkene. Under these conditions, competin g processes such as protonation are minimized, and a different mode of frag mentation from that previously observed with unfunctionalized alkenes(11) i s obtained. The technique is highly sensitive (<0.5 ng), allowing its use i n the identification of insect pheromones. Copyright (C) 1999 John Whey & S ons, Ltd.