Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99354, United States.
GAA Custom Engineering, LLC, P.O. Box 335, Benton City, Washington 99320, United States.
Anal Chem. 2020 Jun 2;92(11):7972-7979. doi: 10.1021/acs.analchem.0c01397. Epub 2020 May 22.
Over the past few years, structures for lossless ion manipulations (SLIM) have used traveling waves (TWs) to move ions over long serpentine paths that can be further lengthened by routing the ions through multiple passages of the same path. Such SLIM "multipass" separations provide unprecedentedly high ion mobility resolving powers but are ultimately limited in their ion mobility range because of the range of mobilities spanned in a single pass; that is, higher mobility ions ultimately "overtake" and "lap" lower mobility ions that have experienced fewer passes, convoluting their arrival time distribution at the detector. To achieve ultrahigh resolution separations over broader mobility ranges, we have developed a new multilevel SLIM possessing multiple stacked serpentine paths. Ions are transferred between SLIM levels through apertures (or ion escalators) in the SLIM surfaces. The initial multilevel SLIM module incorporates four levels and three interlevel ion escalator passages, providing a total path length of 43.2 m. Using the full path length and helium buffer gas, high resolution separations were achieved for Agilent tuning mixture phosphazene ions over a broad mobility range ( ≈ 3.0 to 1.2 cm/(Vs)). High sensitivity was achieved using "in-SLIM" ion accumulation over an extended trapping region of the first SLIM level. High transmission efficiency of ions over a broad mobility range (e.g., ≈ 3.0 to 1.67 cm/(Vs)) was achieved, with transmission efficiency rolling off for the lower mobility ions (e.g., ≈ 1.2 cm/(V*s)). Resolving powers of up to ∼560 were achieved using all four ion levels to separate reverse peptides (SDGRG and GRGDS). A complex mixture of phosphopeptides showed similar coverage could be achieved using one or all four SLIM levels, and doubly charged phosphosite isomers not significantly separated using one SLIM level were well resolved when four levels were used. The new multilevel SLIM technology thus enables wider mobility range ultrahigh-resolution ion mobility separations and expands on the ability of SLIM to obtain improved separations of complex mixtures with high sensitivity.
在过去的几年中，用于无损离子操控（SLIM）的结构利用行波（TW）将离子移动到可以通过将离子通过同一路径的多个通道来进一步延长的长蛇形路径上。这种 SLIM“多通道”分离提供了前所未有的高离子迁移率分辨率，但由于在单次通过中跨越的迁移率范围，它们最终受到限制；也就是说，迁移率较高的离子最终会“超越”并“超越”经历较少通过的迁移率较低的离子，从而使它们在探测器处的到达时间分布变得混乱。为了在更宽的迁移率范围内实现超高分辨率分离，我们开发了一种具有多个堆叠蛇形路径的新型多级 SLIM。离子通过 SLIM 表面中的孔（或离子扶梯）在 SLIM 级别之间传输。初始多级 SLIM 模块包含四个级别和三个级间离子扶梯通道，总路径长度为 43.2 米。使用整个路径长度和氦缓冲气体，在宽迁移率范围内（≈3.0 至 1.2 cm/（Vs））实现了对安捷伦调谐混合物膦嗪离子的高分辨率分离。通过在第一个 SLIM 级别的扩展捕获区域中进行“SLIM 内”离子积累，实现了高灵敏度。在宽迁移率范围内（例如，≈3.0 至 1.67 cm/（Vs））实现了离子的高传输效率，而低迁移率离子（例如，≈1.2 cm/（V*s））的传输效率则下降。使用所有四个离子级达到了高达约 560 的分辨率，以分离反肽（SDGRG 和 GRGDS）。使用一个或所有四个 SLIM 级都可以实现复杂的磷酸肽混合物的类似覆盖率，并且当使用四个级时，使用一个 SLIM 级无法显著分离的双电荷磷酸化位点异构体得到了很好的分离。新的多级 SLIM 技术因此能够实现更宽的迁移率范围超高分辨率离子迁移率分离，并扩展了 SLIM 获得高灵敏度的复杂混合物改善分离的能力。
