Gas-phase ion chemistry of protonated melatonin

摘要

The gas-phase ion chemistry of protonated melatonin has been investigated by mass spectrometric (MS) techniques involving chemical ionisation, fast atom bombardment and electrospray ionisation. Either naturally-occurring or collision-induced decomposition expe_riments have been carried out using side chain tetra-deuterium-labelled derivatives, as well as the corresponding N-D derivatives obtained by exchange with D20. The analysis of experimental results allows definite pathways for the formation of the ion at m/z 174 to be assigned and sheds some more light on the overall fragmentation pathways. Experiments on labelled derivatives evidenced H-D scrambling processes during fragmentation.