The mass spectra of 8-azapurines

The mass spectra of 8-azaadenine, 8-azahypoxanthine, 2,6-diamino-8-azapurine, 8-azaxanthine and 8-azaguanine are all characterized by intense molecular ion peaks. Fragmentation pathways are advanced to account for the other ions observed in the mass spectra and are supported by metastable transitions, accurate mass measurements and deuterium labelling studies. 8-azaadenine and 8-azahypoxanthine fragment initially by elimination of nitrogen from the molecular ion, but this is a minor process with the other compounds. In many respects the electron impact induced fragmentation of the 8-azapurines is analogous to that of the corresponding purine derivatives.