Tandem Mass Spectrometry of Poly(ethylene imine)s by Electrospray Ionization (ESI) and Matrix Assisted Laser Desorption/ionization (MALDI)
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Altuntas, Esra; Knop, Katrin; Tauhardt, Lutz; Kempe, Kristian; Crecelius, Anna; Jäger, Michael; Hager, Martin D.; Schubert, Ulrich S.
- Abstract:
- In this contribution, linear poly(ethylene imine) (PEI) polymers, which are of importance in gene delivery, are investigated in detail by
using electrospray ionization-quadrupole-time of flight (ESI-Q-TOF) and matrix-assisted laser desorption/ionization-time of flight
(MALDI-TOF) mass spectrometry (MS). The analyzed PEIs with different end groups were synthesized using the polymerization of
substituted 2-oxazoline via a living cationic ring-opening polymerization (CROP) and a subsequent hydrolysis under acidic
conditions. The main goal of this study was to identify linear PEI polymers in a detailed way to gain information about their fragmentation
pathways. For this purpose, a detailed characterization of three different linear PEIs was performed by using ESI-Q-TOF and
MALDI-TOF MS in combination with collision-induced dissociation (CID) experiments. In ESI-MS as well as MALDI-MS analysis, the
obtained spectra of PEIs resulted in fittingmass distributions for the investigated PEIs. In the tandemMS analysis, a 1,2-hydride shift
with a charge-remote rearrangement via a four-membered cyclic transition state, as well as charge-induced fragmentation reactions,
was proposed as the main fragmentation mechanisms according to the obtained fragmentation products from the protonated
parent peaks. In addition, heterolytic and homolytic cleavages were proposed as alternative fragmentation pathways. Moreover, a
1,4-hydrogen elimination was proposed to explain different fragmentation products obtained from the sodiated parent peaks.
- Year:
- 2012
- Type of Publication:
- Article
- Keywords:
- tandem mass spectrometry; poly ethylene imines; collision-induced dissociation; fragmentation mechanism; electrospray ionization
- Journal:
- Journal of Mass Spectrometry
- Volume:
- 47
- Pages:
- 105-114