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Poster Presentations
Day 2, June 23（Mon.）
Room P (Maesato East, Foyer, Ocean Wing)
- 2P-AM-32
Unique Fragmentation of Indole Alkaloids Induced by Neutral Reactive Species Formed From Microwave Hydrogen and Water Plasma
(1Univ. Melbourne, 2Nagasaki Univ., 3RIKEN, 4Shimadzu Corp.)
oJack Li1, Chris Bowen1, Bun Chan2,3, Hidenori Takahashi4, Richard O'hair1
The development of an oxygen attachment dissociation (OAD) radical source that produces hydrogen atoms, hydroxyl radicals and oxygen atoms from microwave-excited hydrogen and water plasmas provides an opportunity to study the OAD reactions of a diverse range of analytes on LCMS timescales.
ESI-MS followed by OAD of the [M + H]+ of reserpine, an indole alkaloid used to treat high blood pressure, results in the formation of the oxygen adduct, [M + H + O]+ (m/z 625), and a fragment ion at m/z 450. These product ions are unique to OAD conditions. Computational chemistry studies using DFT calculations suggest that the oxygen atom reacts across the C-C double bond adjacent to the amine, and a plausible exothermic pathway exists to form the m/z 450 fragment ion. OAD experiments of methylated and dehydrogenated reserpine derivatives also show oxygen adducts, but unique fragmentation was observed on the methylated derivative; DFT calculations of oxygen addition to the dehydrogenated species find alternate pathways to be thermodynamically favourable which may form stable singlet oxygen adducts instead of undergoing fragmentation. The methylated derivative shows a unique m/z 464 fragment, similar to that observed in reserpine experiments, and fragments formed by loss of the methyl group.