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Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation

Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation
Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation
The experimental investigation of site-specific intra-ionic hydrogen/deuterium (H/D) exchange in the low-energy collision-induced dissociation (CID) product ion spectra of protonated small molecules generated by electrospray ionisation (ESI) is presented. The observation of intra-ionic H/D exchange in such ions under low-energy CID conditions has hitherto been rarely reported. The data suggest that the intra-ionic H/D exchange takes place in a site-specific manner between the ionising deuteron, localised at either a tertiary amine or a tertiary amine-N-oxide, and a -hydrogen relative to the nitrogen atom. Nuclear magnetic resonance (NMR) spectroscopy measurements showed that no H/D exchange takes place in solution, indicating that the reaction occurs in the gas phase. The compounds analysed in this study suggested that electron-withdrawing groups bonded to the carbon atom bearing the -hydrogen can preclude exchange. The effect of the electron-withdrawing group appears dependent upon its electronegativity, with lower value groups still allowing exchange to take place. However, the limited dataset available in this study prevented robust conclusions being drawn regarding the effect of the electron-withdrawing group. The observation of site-specific intra-ionic H/D exchange has application in the area of structural elucidation, where it could be used to introduce an isotopic label into the carbon skeleton of a molecule containing specific structural features. This could increase the throughput, and minimise the cost, of such studies due to the obviation of the need to produce a deuterium-labelled analogue by synthetic means.
collision-induced dissociation, deuterium, hydrogen/deuterium exchange, isotopes, small molecules, structural elucidation
1076-5174
347-357
Holman, Stephen W.
32d02653-e41d-4615-a660-356fb38b1988
Wright, Patricia
553f5be8-e0fc-41be-ac24-8ffb21cfca82
Wells, N
86312185-007b-495b-86da-4e2e5b9b8025
Langley, G. John
7ac80d61-b91d-4261-ad17-255f94ea21ea
Holman, Stephen W.
32d02653-e41d-4615-a660-356fb38b1988
Wright, Patricia
553f5be8-e0fc-41be-ac24-8ffb21cfca82
Wells, N
86312185-007b-495b-86da-4e2e5b9b8025
Langley, G. John
7ac80d61-b91d-4261-ad17-255f94ea21ea

Holman, Stephen W., Wright, Patricia, Wells, N and Langley, G. John (2010) Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation. Journal of Mass Spectrometry, 45 (4), 347-357. (doi:10.1002/jms.1714).

Record type: Article

Abstract

The experimental investigation of site-specific intra-ionic hydrogen/deuterium (H/D) exchange in the low-energy collision-induced dissociation (CID) product ion spectra of protonated small molecules generated by electrospray ionisation (ESI) is presented. The observation of intra-ionic H/D exchange in such ions under low-energy CID conditions has hitherto been rarely reported. The data suggest that the intra-ionic H/D exchange takes place in a site-specific manner between the ionising deuteron, localised at either a tertiary amine or a tertiary amine-N-oxide, and a -hydrogen relative to the nitrogen atom. Nuclear magnetic resonance (NMR) spectroscopy measurements showed that no H/D exchange takes place in solution, indicating that the reaction occurs in the gas phase. The compounds analysed in this study suggested that electron-withdrawing groups bonded to the carbon atom bearing the -hydrogen can preclude exchange. The effect of the electron-withdrawing group appears dependent upon its electronegativity, with lower value groups still allowing exchange to take place. However, the limited dataset available in this study prevented robust conclusions being drawn regarding the effect of the electron-withdrawing group. The observation of site-specific intra-ionic H/D exchange has application in the area of structural elucidation, where it could be used to introduce an isotopic label into the carbon skeleton of a molecule containing specific structural features. This could increase the throughput, and minimise the cost, of such studies due to the obviation of the need to produce a deuterium-labelled analogue by synthetic means.

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More information

Published date: 12 January 2010
Keywords: collision-induced dissociation, deuterium, hydrogen/deuterium exchange, isotopes, small molecules, structural elucidation

Identifiers

Local EPrints ID: 147741
URI: http://eprints.soton.ac.uk/id/eprint/147741
ISSN: 1076-5174
PURE UUID: 9dddecbd-e534-4844-9486-b73caf2e1595
ORCID for N Wells: ORCID iD orcid.org/0000-0002-4607-5791
ORCID for G. John Langley: ORCID iD orcid.org/0000-0002-8323-7235

Catalogue record

Date deposited: 26 Apr 2010 12:47
Last modified: 29 Oct 2019 02:08

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