Study of Fragmentation Behavior for 4 Artemisinins by Electrospray Ionization Mass Spectrometry

To investigate the fragmentation behavior of artemisinins, 4 artemisinins were analyzed using electrospray ionization/time of flight mass spectrometry (ESI-TOF MS) by collision induced dissociation (CID). The samples were infused into the ion source with a syringe pump, and mass spectrometry was operated in the positive ion mode. The mass spectra was obtained mainly by analyzing the fragments of the four compounds. The quasi-molecular ion M+Na⁺ was selected as internal reference ion for collection．The accurate masses and elemental compositions of the fragment ions were determined．The proposed fragmentation patterns of the mass spectra were explained. The mass spectra and structures of 4 artemisinins were compared with each other, it was observed that artemisinins mainly fragmented on O-O and C-O, and gave characteristic fragment ions by the neutral loss of H₂O,CO,HCOOH and CH₃COOH. The common fragment ions of m/z 261 and m/z 163 were also found in artemisinin derivatives. These characteristics can be used for future structures elucidation in studies of artemisinins．