Charge/radical site initiation versus coulombic repulsion for cleavage of multiply charged ions. Charge solvation in poly(alkene glycol) ions.
Electrospray ionization of poly(ethylene glycol) (PEG) followed by separation with Fourier-transform mass spectrometry traps (PEG100 + nH)n+ ions. Both collisionally activated dissociation (CAD) and electron capture dissociation (ECD) of these ions (n = 5, 6, 7) produce PEGx fragment ions in which the x values correspond closely to those for an equal distribution of charges in the linear polymer ion, e.g., for n = 7, near x = 1, 17, 34, 50, 67, 83, and 100. However, positions intermediate between these charges should represent the maximum coulombic repulsion, so this is not a specific driving force for fragmentation, which is instead consistent with charge site (CAD) or radical site (ECD) initiation. These conclusions were confirmed by studies of a variety of other poly(alkene glycol) polymers. For these, the ECD spectra of the protonated species are consistent with the predicted charge solvation by the ion's oxygen atoms.
Cerda
B A
BA
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.
Breuker
K
K
Horn
D M
DM
McLafferty
F W
FW
D000465:Algorithms; D000475:Alkenes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008962:Models, Theoretical; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D000475:Alkenes; D007477:Ions; D011108:Polymers; D011092:Polyethylene Glycols