Electron impact mass spectrometry of maleimycin

The mass spectrometric behaviour of maleimycin, a bicyclic maleimide antibiotic, is discussed in detail with the aid of exact mass measurements, metastables (linked scans B/E and B2/E), ionization and appearance energy measurements and deuterium labelling experiments. The unusual loss of NH3 from the molecular ion is highlighted and a possible mechanism is proposed.