Key fragmentation patterns of aporphine alkaloids by electrospray ionization with multistage mass spectrometry

This work reports a detailed study of the fragmentations of aporphine alkaloids by electrospray ionization with multistage mass spectrometry (ESI-MSn) in positive mode. In a first step the loss of the amino group and its substituent is observed. Further steps display the loss of the peripheral groups. Losses of methanol and CO are observed if an OH is vicinal to an OCH3 on the aromatic ring. Otherwise the spectra show radical losses of CH3. or CH3O. as the main fragmentations. If a methylenedioxy group is present losses of formaldehyde followed by CO are observed. These fragmentations yield important information on the structures of aporphines.