In-source collision induced dissociation (ISCID) of polyethylene glycol (PEG) and polypropylene glycol (PPG) cationized by alkali metal ions was studied as a function of the chain length and collision energy using electrospray ionization mass spectrometry (ESI MS). The dissociation of the sodiated, potassiated and cesiated PEG and PPG yielded a neutral polyether and a cation without the formation of product ions resulting from the backbone cleavages. The survival yield (SY) method was applied to characterize the in-source fragmentation behavior of the cationized polyethers. The SY curves obtained by tandem MS/MS CID and in-source CID were compared. A remarkable difference was found, i.e. increasing the collision energy, the polyethers entirely dissociate in the collision cell, while the in-source SY plots level off at about 0.1-0.3. The finite SY values at large ISCID collision energies may suggest ion-molecule reactions in the ISCID region of the instrument. It was found that the characteristic ISCID50 collision energy corresponding to SY = 0.5 was dependent linearly on the number of the repeat units, i.e., on the size of the polyethers.
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry