Fu Liangxuan, Eakins Gregory S, Carlsen Mark S, McLuckey Scott A
Department of Chemistry, Purdue University, West Lafayette, IN, USA 47907-2084.
Int J Mass Spectrom. 2024 Sep;503. doi: 10.1016/j.ijms.2024.117282. Epub 2024 Jun 25.
Single-frequency ion parking, a useful technique in electrospray mass spectrometry (ESI-MS), involves gas-phase charge-reduction ion/ion reactions in an electrodynamic ion trap in conjunction with the application of a supplementary oscillatory voltage to selectively inhibit the reaction rate of an ion of interest. The ion parking process provides a means for limiting the extent of charge reduction in a controlled fashion and allows for ions distributed over a range of charge states to be concentrated into fewer charge states (a single charge state under optimal conditions). As charge reduction inherently leads to an increase in the mass-to-charge () ratio of the ions, it is important that the means for storing and analyzing ions be able to accommodate ions of high ratios. The so-called 'digital ion trap' (DIT), which uses a digital waveform as the trapping RF, has been demonstrated to be well-suited for the analysis of high ions by taking advantage of its ability to manipulate the waveform frequency. In this study, the feasibility of ion parking in a 3D quadrupole ion trap operated as a DIT using a slow-amplitude single-frequency sine-wave for selective inhibition of an ion/ion reaction is demonstrated. A recently described model that describes ion parking has been adjusted for the DIT case and is used to interpret experimental data for proteins ranging in mass from 8600 Da to 467,000 Da.
单频离子驻留是电喷雾质谱（ESI-MS）中的一项有用技术，它涉及在电动离子阱中进行气相电荷减少离子/离子反应，并施加辅助振荡电压以选择性抑制目标离子的反应速率。离子驻留过程提供了一种以可控方式限制电荷减少程度的方法，并允许分布在一系列电荷态的离子集中到较少的电荷态（在最佳条件下为单一电荷态）。由于电荷减少本质上会导致离子质荷比（）增加，因此存储和分析离子的方法能够容纳高比离子非常重要。所谓的“数字离子阱”（DIT），它使用数字波形作为捕获射频，已被证明通过利用其操纵波形频率的能力非常适合分析高离子。在本研究中，展示了在作为DIT运行的三维四极杆离子阱中使用慢振幅单频正弦波进行离子驻留以选择性抑制离子/离子反应的可行性。最近描述的一个描述离子驻留的模型已针对DIT情况进行了调整，并用于解释质量范围从8600 Da到467,000 Da的蛋白质的实验数据。
