An ion-trap mass spectrometric study on electron impact and collisionally induced decomposition pathways of some phenothiazine S-oxides

The electron ionization (EI) mass spectra and the daughter‐ion spectra of the EI‐generated main fragments of phenothiazine S‐oxides and its two N‐substituted derivatives have been studied by means of ion‐trap mass spectrometry (ITMS). Interesting differences with the data already published on the same molecules as obtained by a magnetic sector instrument have been rationalized by considering how, under ITMS conditions, charge exchange or self‐chemical‐ionization phenomena can take place, leading to molecular species with low energy content.