Letter:: Fast atom bombardment, electrospray, ionspray and tandem mass spectrometry of 1 : 1 β-cyclodextrin/5-methoxytryptamine hydrochloride host-guest complex:: host protonation and fragmentation due to guest deamination

The 1 : 1 inclusion complex of beta -cyclodextrin (beta CD) with 5-methoxytryptamine (5MTA) hydrochloride was studied by mass spectrometry (MS) and tandem-MS with fast atom bombardment (FAB), electrospray (ES) and ionspray (IS) ionisation and triple quadrupole or ion trap analysers. A protonated 1 : 1 beta CD/MTA gaseous association was always observed; the protonated species of deaminated 5MTA and of some typical beta CD fragments were obtained, in addition to the expected protonated 5MTA, as tandem-MS dissociation products. A reaction pattern starting from the deamination of protonated 5MTA, as a recently described high pressure chemical ionisation or ES process of primary amines, was suggested, which accounts for the formation of excited protonated beta CD and its fragmentation by tandem-MS, even under unimolecular conditions.