Fragmentation of deprotonated polyethylene glycols, [PEG – H]–
Article first published online: 10 JUN 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Rapid Communications in Mass Spectrometry
Volume 27, Issue 14, pages 1643–1648, 30 July 2013
How to Cite
Hester, T. H., Castillo, D. E. and Goebbert, D. J. (2013), Fragmentation of deprotonated polyethylene glycols, [PEG – H]–. Rapid Commun. Mass Spectrom., 27: 1643–1648. doi: 10.1002/rcm.6615
- Issue published online: 10 JUN 2013
- Article first published online: 10 JUN 2013
- Manuscript Accepted: 28 APR 2013
- Manuscript Revised: 25 APR 2013
- Manuscript Received: 21 MAR 2013
Polyethylene glycols (PEGs) are soluble molecules utilized in a wide range of applications. Mass spectrometry and fragmentation patterns of positively charged PEG oligomers are well-known, but decomposition mechanisms of the deprotonated ions have not been studied.
Deprotonated PEGs were generated by electrospray ionization of PEG in water/acetonitrile. Collision-induced dissociation (CID) experiments were carried out in a tandem mass spectrometer. The anions were studied using a tandem mass spectrometer to carry out CID experiments. A series of small PEG oligomers, with 1 to 8 monomer units, were studied in order to monitor size-dependent effects on fragmentation reactions.
Because deprotonated PEG ions have a unique charge site, their dissociation pathways can easily be monitored. The ions fragment by loss of C2H4O monomer units, with an alternating intensity pattern that suggests the loss of an even number of monomer units is favored. Smaller oligomers and oligomer fragments also yielded fragments corresponding to H2 elimination and H2O loss. H2 elimination occurs by the generation of a hydride ion which deprotonates an alcohol upon leaving, while dehydration appears to be a charge-remote process.
The fragmentation of deprotonated PEG is dominated by intramolecular SN2 reactions involving the terminal oxide anion. Copyright © 2013 John Wiley & Sons, Ltd.