Ion mobility spectrometry (IMS) mass spectrometry (MS) centers on the ability to separate gaseous structures by size, charge, shape, and followed by mass-to-charge (m/z). For oligomeric structures, improved separation is hypothesized to be related to the ability to extend structures through repulsive forces between cations electrostatically bonded to the oligomers. Here we show the ability to separate differently branched multiply charged ions of star-branched poly(ethylene glycol) oligomers (up to 2000 Da) regardless of whether formed by electrospray ionization (ESI) charged solution droplets or from charged solid particles produced directly from a surface by matrix-assisted ionization. Detailed structural characterization of isomers of the star-branched compositions was first established using a home-built high-resolution ESI IMS-MS instrument. The doubly charged ions have well-resolved drift times, achieving separation of isomers and also allowing differentiation of star-branched versus linear oligomers. An IMS-MS "snapshot" approach allows visualization of architectural dispersity and (im)purity of samples in a straightforward manner. Analyses capabilities are shown for different cations and ionization methods using commercially available traveling wave IMS-MS instruments. Analyses directly from surfaces using the new ionization processes are, because of the multiply charging, not only associated with the benefits of improved gas-phase separations, relative to that of ions produced by matrix-assisted laser desorption/ionization, but also provide the potential for spatially resolved measurements relative to ESI and other ionization methods.

中文翻译：

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使用多电荷离子通过IMS-MS解析星型支化聚乙二醇的异构体。

离子迁移谱（IMS）质谱（MS）的重点是通过尺寸，电荷，形状和质荷比（m / z）分离气态结构的能力。对于低聚物结构，假设改善的分离与通过静电键合到低聚物上的阳离子之间的排斥力扩展结构的能力有关。在这里，我们展示了能够分离星形支化聚（乙二醇）低聚物（至多2000 Da）的不同分支的多带电离子的能力，无论是通过电喷雾电离（ESI）带电溶液液滴还是从直接由碳纳米管产生的带电固体颗粒形成的表面通过基质辅助电离。首先使用自制的高分辨率ESI IMS-MS仪器建立了星形支化组合物异构体的详细结构表征。双电荷离子具有很好的漂移时间，可以实现异构体的分离，并且还可以区分星形支链和线性低聚物。IMS-MS的“快照”方法允许以简单的方式可视化架构的分散性和样本的（不纯）纯度。显示了使用市售行波IMS-MS仪器对不同阳离子和电离方法的分析能力。由于采用了多重电荷，直接使用新的电离过程从表面进行分析不仅与改进的气相分离（相对于基质辅助激光解吸/电离产生的离子）的好处有关，而且还提供了潜在的优势相对于ESI和其他电离方法的空间分辨测量。