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Accelerated high-resolution differential ion mobility separations using hydrogen.

ABSTRACT: The resolving power of differential ion mobility spectrometry (FAIMS) was dramatically increased recently by carrier gases comprising up to 75% He or various vapors, enabling many new applications. However, the need for resolution of complex mixtures is virtually open-ended and many topical analyses demand yet finer separations. Also, the resolving power gains are often at the expense of speed, in particular making high-resolution FAIMS poorly compatible with online liquid-phase separations. Here, we report FAIMS employing hydrogen, specifically in mixtures with N(2) containing up to 90% H(2). Such compositions raise the mobilities of all ions and thus the resolving power beyond that previously feasible, while avoiding the electrical breakdown inevitable in He-rich mixtures. The increases in resolving power and ensuing peak resolution are especially significant at H(2) fractions above ~50%. Higher resolution can be exchanged for acceleration of the analyses by up to ~4 times. For more mobile species such as multiply charged peptides, this exchange is presently forced by the constraints of existing FAIMS devices, but future designs optimized for H(2) should consistently improve resolution for all analytes.

SUBMITTER: Shvartsburg AA

PROVIDER: S-EPMC3234991 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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Accelerated high-resolution differential ion mobility separations using hydrogen.

Shvartsburg Alexandre A AA Smith Richard D RD

Analytical chemistry 20111110 23

The resolving power of differential ion mobility spectrometry (FAIMS) was dramatically increased recently by carrier gases comprising up to 75% He or various vapors, enabling many new applications. However, the need for resolution of complex mixtures is virtually open-ended and many topical analyses demand yet finer separations. Also, the resolving power gains are often at the expense of speed, in particular making high-resolution FAIMS poorly compatible with online liquid-phase separations. Her ...[more]

PMID: 22074292

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Project description: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 (K0 ≈ 3.0 to 1.2 cm2/(V*s)). 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., K0 ≈ 3.0 to 1.67 cm2/(V*s)) was achieved, with transmission efficiency rolling off for the lower mobility ions (e.g., K0 ≈ 1.2 cm2/(V*s)). Resolving powers of up to ∼560 were achieved using all four ion levels to separate reverse peptides (SDGRG1+ and GRGDS1+). 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.

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Dataset Information

Accelerated high-resolution differential ion mobility separations using hydrogen.

Publications

Accelerated high-resolution differential ion mobility separations using hydrogen.

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