Multiple Gas-Phase Conformations of a Synthetic Linear Poly(acrylamide) Polymer Observed Using Ion Mobility-Mass Spectrometry.

Abstract

Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,…). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths. A unique collision cross-section (CCS) trend is usually observed when increasing the degree of polymerization (DP) at constant charge state, allowing the deciphering of different polymer topologies. In this paper, we report multiple coexisting CCS trends when increasing the DP at constant charge state for linear poly(acrylamide) PAAm in the gas phase. This is similar to observations on peptides and proteins. Biomolecules show in addition population changes when collisionally heating the ions. In the case of synthetic PAAm, fragmentation occurred before reaching the energy for conformation conversion. These observations, which were made on two different IM-MS instruments (SYNAPT G2 HDMS and high resolution multi-pass cyclic T-Wave prototype from Waters), limit the use of ion mobility for synthetic polymer topology interpretations to polymers where unique CCS values are observed for each DP at constant charge state

J Am Soc Mass Spectrom. 2017 Nov;28(11):2492-2499. doi: 10.1007/s13361-017-1769-x. Epub  2017 Aug 14.
Haler JRN1, Far J2, Aqil A3, Claereboudt J4, Tomczyk N5, Giles K5, Jérôme C3, De Pauw E2.
1 Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium. jean.haler@ulg.ac.be.
2 Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium.
3 Center for Education and Research on Macromolecules, Department of Chemistry, University of Liège, Quartier Agora, Allée du Six Aout 13, B-4000, Liège, Belgium.
4 Waters Corporation, Connexion Business Park, Brusselsesteenweg 500, 1731, Zellik, Belgium.5Waters Corporation, Stamford Ave., Wilmslow, SK9 4AX, UK.
 

KEYWORDS:
Ion mobility-mass spectrometry; Multi-pass cyclic traveling wave; Multiple conformations; PAAm; Poly(acrylamide); Synapt G2; Synthetic polymer

PMID: 28808984  DOI: 10.1007/s13361-017-1769-x