Low-energy mass spectra of some aliphatic ketones

The charge exchange mass spectra of a selection of C₅-C₇ ketones have been measured using CS₂]⁺˙, COS]⁺˙ and N₂O]_+. as reagent ions. The low energy charge exchange with CS₂]⁺˙ or COS]⁺˙ provides simple primary ion mass spectra, which readily permit structure elucidation in contrast to metastable ion spectra. In several cases, isomer distinction is easier from the charge exchange mass spectra than from the electron impact mass spectra. The energy transfer from N₂O]⁺˙ is sufficiently high for complex spectra resembling electron impact mass spectra to be obtained.