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Fragmentation of deprotonated polyethylene glycols, [PEG – H] –
Author(s) -
Hester Thomas H.,
Castillo Daniel E.,
Goebbert Daniel J.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6615
Subject(s) - chemistry , deprotonation , fragmentation (computing) , dissociation (chemistry) , monomer , collision induced dissociation , tandem mass spectrometry , mass spectrometry , peg ratio , photochemistry , ion , organic chemistry , chromatography , polymer , finance , computer science , economics , operating system
RATIONALE 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. METHODS 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. RESULTS Because deprotonated PEG ions have a unique charge site, their dissociation pathways can easily be monitored. The ions fragment by loss of C 2 H 4 O 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 H 2 elimination and H 2 O loss. H 2 elimination occurs by the generation of a hydride ion which deprotonates an alcohol upon leaving, while dehydration appears to be a charge‐remote process. CONCLUSIONS The fragmentation of deprotonated PEG is dominated by intramolecular S N 2 reactions involving the terminal oxide anion. Copyright © 2013 John Wiley & Sons, Ltd.