Mass Spectrometry Laboratory, University of Liège, Quartier Agora, Allée du Six Aout 11, B-4000, Liège, Belgium.
Center for Education and Research on Macromolecules, Department of Chemistry, University of Liège, Quartier Agora, Allée du Six Aout 13, B-4000, Liège, Belgium.
J Am Soc Mass Spectrom. 2017 Nov;28(11):2492-2499. doi: 10.1007/s13361-017-1769-x. Epub 2017 Aug 14.
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. Graphical Abstract ᅟ.
离子淌度-质谱联用（IM-MS）已经成为一种强大的分离和鉴定工具，用于表征合成聚合物混合物和拓扑结构（线性、环状、星形等）。电喷雾与 IM-MS 相结合，已经揭示了即使使用分辨率有限的 IM-MS 仪器，对于具有强分子内相互作用的单一电荷状态的生物分子，也存在几种电荷状态依赖性构象的共存。对于合成聚合物，样品的多分散性允许观察到几种链长。当在恒定电荷状态下增加聚合度（DP）时，通常会观察到独特的碰撞截面（CCS）趋势，这允许解析不同的聚合物拓扑结构。在本文中，我们报道了在气相中线性聚（丙烯酰胺）PAAm 中在恒定电荷状态下增加 DP 时会出现多个共存的 CCS 趋势。这类似于在肽和蛋白质上的观察结果。生物分子在离子碰撞加热时会发生种群变化。在合成 PAAm 的情况下，在达到构象转换所需的能量之前发生了碎裂。这些观察结果是在两种不同的 IM-MS 仪器（SYNAPT G2 HDMS 和 Waters 的高分辨率多通循环 T-Wave 原型）上进行的，限制了离子淌度在合成聚合物拓扑解释中的应用，仅适用于在恒定电荷状态下每个 DP 观察到独特 CCS 值的聚合物。
