Influence of differently ionized species on fragmentation pathways and energetics of a potential adenosine receptor antagonist using a triple quadrupole and a multistage LTQ-Orbitrap™ FTMS instrument

✍ Scribed by Wendy Zhong; Patrick A. Irish; Gary E. Martin

• Book ID: 102892144
• Publisher: Journal of Heterocyclic Chemistry
• Year: 2009
• Tongue: English
• Weight: 594 KB
• Volume: 46
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.196

✦ Synopsis

Abstract

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A systematic study was conducted to investigate the influence of differently ionized species on the fragmentation pathways and energetics of a piperazine‐containing adenosine by using different cations or anions. Very different fragmentation mechanisms were observed in protonated‐ versus sodiated‐molecules, which indicated that the proton is mobilized to promote the charge‐direct fragmentation, whereas Na^+^ cation was fixed at the heterotricyclic ring structure provoking charge‐remote fragment ions. This finding was also supported by the results observed in the fragmentation behaviors in the deprotonated‐molecule. The energetics of these fragment ions were also explored by using the breakdown curves obtained from the triple quadrupole and LTQ‐Orbitrap™ instrument. The data indicated that the lowest energy pathways in the protonated‐molecule [M+H]^+^ involve breaking a CN bond connecting an ethylene bridge and heterotricyclic ring structure. The lowest energy pathway is the cleavage of a CO bond connecting the methoxy ethyl group and phenolic oxygen to form a distonic radical ion for a sodiated‐molecule [M+Na^+^]and a deprotonated‐molecule [M‐H]^−^. The data suggest that by choosing the differently ionized species, one can probe different fragmentation channels that can provide additional structure information for an unknown impurity and possibly degradation product identification. In addition, by comparing the data obtained from triple quadrupole and LTQ‐Orbitrap instruments, one can develop further understanding of the differences in the fragmentation behaviors due to the variations in the collision activation‐dissociation process. From the side‐by‐side comparison with the breakdown curves obtained for both instruments, the difference in fragmentation behaviors caused by the difference in dissociation processes that occur in these two types of instruments can be probed. J. Heterocyclic Chem., (2009).