A Novel Ion Pseudo-trapping Phenomenon within Traveling Wave Ion Guides
A Novel Ion Pseudo-trapping Phenomenon within Traveling Wave Ion Guides
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DOI：
10.1021/jasms.9b00095
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发表时间：
2020-04-01
影响因子：
3.2
通讯作者：
Ruotolo, Brandon T.
中科院分区：
文献类型：
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作者：
Dixit, Sugyan M.;Richardson, Keith;Ruotolo, Brandon T.
行波离子迁移率（TWIM）技术在组学和结构生物学等领域的广泛应用促使我们努力加深对此类设备内离子传输的理解。在这里，我们描述了TWIM理论的新进展，其中TW离子引导器内的伪捕获的详细特征。在伪俘获过程中，具有不同迁移率的离子可以以相同的平均速度行进，使同一TWIM实验中的其他离子正常分离。此外，伪俘获限制了离子在TWIM期间经历的典型谱带加宽，表现为具有明显改善的IM分辨能力的峰，但是经历伪俘获的所有离子都不能通过IM分离。SIMION模拟表明，在伪俘获过程中，离子相对于TW参考系被锁定成重复的运动模式。我们开发了一个简化的模型，能够再现TW伪捕获和再现实验数据中观察到的趋势。我们的模型和模拟表明，伪捕获只发生在静态TWIM条件下进行的实验，在一定程度上，这取决于行波的详细形状。我们表明，伪捕获改变离子渡越时间，并可能对校准CCS测量产生不利影响。最后，我们提供了避免TWIM中无意伪捕获的建议，以获得最佳的分离和CCS测定。
The widespread use of traveling wave ion mobility (TWIM) technology in fields such as omics and structural biology motivates efforts to deepen our understanding of ion transport within such devices. Here, we describe a new advancement in TWIM theory, where pseudo-trapping within TW ion guides is characterized in detail. During pseudo-trapping, ions with different mobilities can travel with the same mean velocity, leaving others within the same TWIM experiment to separate as normal. Furthermore, pseudo-trapping limits typical band broadening experienced by ions during TWIM, manifesting as peaks with apparently improved IM resolving power, but all ions that undergo pseudo trapping are unable to separate by IM. SIMION simulations show that ions become locked into a repeated pattern of motion with respect to the TW reference frame during pseudo-trapping. We developed a simplified model capable of reproducing TW pseudo-trapping and reproducing trends observed in experimental data. Our model and simulations suggest that pseudotrapping occurs only during experiments performed under static TWIM conditions, to an extent that depends on the detailed shape of the traveling wave. We show that pseudo-trapping alters the ion transit times and can adversely affect calibrated CCS measurements. Finally, we provide recommendations for avoiding unintentional pseudo-trapping in TWIM in order to obtain optimal separations and CCS determinations.