Gas Phase Reactions of Iron, Copper and Rhodium Cations with Monoterpenes

Monoterpene hydrocarbons C10H16 are emitted by the vegetation to the atmosphere, where they participate in the atmospheric chemistry and aerosols formation. Thus there is a need to analyse their concentrations selectively with measurement time less than 1 s. This task could not be solved solely by gas chromatography and one of the possible solutions is selective reagent ions in chemical ionization mass spectrometry techniques. This study presents product ion distributions of the gas phase single collision reactions of Fe+, Cu+ and Rh+ metal cations with seven monoterpenes: α-pinene, sabinene, myrcene, 3-carene, ocimene, β-pinene and α-phellandrene. Some distinctive product ion patterns were noticed: C5H8 loss in reactions with Fe+, C10H16 adduct formation with Cu+, and series of H2 losses in with Rh+. Application of these results are discussed, particularly that a combination of few reagent ions should be utilized in order to analyse monoterpenes mixture selectively.