Mass Spectrometric Investigation of 5,6- and 5,7-Dihydroxytryptamines and their Biological Precursors

Abstract

A mass spectrometric investigation of tryptamine, 5-hydroxytryptamine and 5,6- and 5,7-dihydroxytryptamine was carried out using two different ionization methods, metastable ion studies and accurate mass measurements. In electron impact (EI) conditions, a series of decomposition processes, clearly related to the structure of neutral molecules, was evidenced, although 5,7-dihydroxytryptamine showed severe problems related to its vaporization. The characterization of the two isomeric compounds was possible only by ion trap mass spectrometry. In fast atom bombardment conditions, decomposition pathways analogous to those observed in EI conditions were detected, and new decomposition channels due to NH 3 and NH 2 loss indicated that protonation takes place on the primary amine nitrogen atom.