Determination of Gas-Phase Ion Mobility Coefficients Using Voltage Sweep Multiplexing

Reinecke, Tobias; Davis, Austen L.; Clowers, Brian H.

doi:10.1007/s13361-019-02182-x

Cited by 20 publications

(23 citation statements)

References 47 publications

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“…The HiKE-IMS resolving power varies from R = 57 at high field (100 Td) to R = 65 at lower field (40 Td) in the drift region. By varying the potential of the Faraday grid according to the tristate ion shutter mechanism, this grid formation also serves as second ion gate allowing to transfer selected peaks of the ion mobility spectrum into the MS, as known from other IMS-MS couplings. − …”

Section: Methodsmentioning

confidence: 99%

Analyzing Positive Reactant Ions in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS) by HiKE-IMS–MS

Allers

Kirk

Roßbitzky

et al. 2020

J. Am. Soc. Mass Spectrom.

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In contrast to classical ion mobility spectrometers (IMS) operating at ambient pressure, the high kinetic energy ion mobility spectrometer (HiKE-IMS) is operated at reduced pressures between 10–40 mbar. In HiKE-IMS, ions are generated in a reaction region before they are separated in a drift region. Due to the operation at reduced pressure, it is possible to reach high reduced electric field strengths up to 120 Td in both the reaction as well as drift region, resulting in a pronounced decrease in chemical cross sensitivities and a significant enhancement of the dynamic range. Until now though, only limited knowledge about the ionization pathways in HiKE-IMS is available. Typically, proton bound water clusters, H+(H2O) n , are the most abundant positive reactant ion species in classical IMS with atmospheric chemical ionization sources. However, at reduced pressure and increased effective ion temperature, the reactant ion population significantly changes. As the ionization efficiency of analyte molecules in HiKE-IMS strongly depends on the reactant ion population, a detailed knowledge of the reactant ion population generated in HiKE-IMS is essential. Here, we present a coupling stage of the HiKE-IMS to a mass spectrometer enabling the identification of ion species and the investigation of ion molecule reactions prevailing in HiKE-IMS. In the present study, the HiKE-IMS–MS is used to identify positive reactant ion populations in both, purified air and nitrogen, respectively. The experimental data suggest the generation of systems of clustered primary ions (H+(H2O) n , NO+(H2O) m , and O2 +(H2O) p ), which most probably serve as reactant ions. Their relative abundances highly depend on the reduced electric field strength in the reaction region. Furthermore, their effective mobilities are studied as a function of the reduced electric field strength in the drift region.

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Section: Methodsmentioning

confidence: 99%

Analyzing Positive Reactant Ions in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS) by HiKE-IMS–MS

Allers

Kirk

Roßbitzky

et al. 2020

J. Am. Soc. Mass Spectrom.

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“…Poltash et al presented a Fourier transform ion mobility spectrometer coupled to an Orbitrap mass spectrometer for improved ion transmission and throughput in mismatched duty cycle instruments . Another method to better utilize ions in an IMS experiment is multiplexing. − A multiplexed IMS spectrum, which is a composite of separation arising from each packet, is then deconvoluted to obtain the true spectrum with improved S/N. However, ion utilization efficiency is still limited (depending on the length of the pseudorandom injection sequence of the multiplexing scheme), and the data processing (demultiplexing) typically introduces artifacts for low abundance species, leading to false negatives in detection upon artifact removal .…”

Section: Introductionmentioning

confidence: 99%

Ion Mobility Spectrometry with High Ion Utilization Efficiency Using Traveling Wave-Based Structures for Lossless Ion Manipulations

Nagy

Conant

et al. 2020

Anal. Chem.

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Ion packets introduced from gates, ion funnel traps, and other conventional ion injection mechanisms produce ion pulse widths typically around a few microseconds or less for ion mobility spectrometry (IMS)-based separations on the order of 100 milliseconds. When such ion injection techniques are coupled with ultralong path length traveling wave (TW)-based IMS separations (i.e., on the order of seconds) using structures for lossless ion manipulations (SLIMs), typically very low ion utilization efficiency is achieved for continuous ion sources [e.g., electrospray ionization (ESI)]. Even with the ability to trap and accumulate much larger populations of ions than being conventionally feasible over longer time periods in SLIM devices, the subsequent long separations lead to overall low ion utilization. Here, we report the use of a highly flexible SLIM arrangement, enabling concurrent ion accumulation and separation and achieving near-complete ion utilization with ESI. We characterize the ion accumulation process in SLIM, demonstrate >98% ion utilization, and show both increased signal intensities and measurement throughput. This approach is envisioned to have broad utility to applications, for example, involving the fast detection of trace chemical species.

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“…Ion mobility experiments were performed using an atmospheric pressure dual-gate PCB drift tube system operating under ambient conditions (∼690–700 Torr, ∼25 °C). The drift region of the IMS was 17.4 cm and bracketed by two sets of ion gates following the trigrid shutter principles outlined by Reinecke et al and Langejuergen et al The ion gates were driven by a set of open-source ion gate pulsers described previously. − Prior to the drift region, ions are desolvated in a 10 cm region containing the same electric field gradient as the drift cell. Voltages applied to the drift region were ∼490 V cm –1 for all experiments.…”

Section: Experimental Methodsmentioning

confidence: 99%

Synchronized Stepped Frequency Modulation for Multiplexed Ion Mobility Measurements

Cabrera

Clowers

2022

J. Am. Soc. Mass Spectrom.

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Implementation of frequency-encoded multiplexing for ion mobility spectrometry (e.g., Fourier transform ion mobility spectrometry (FT-IMS)) has facilitated the direct coupling of drift tube ion mobility instrumentation with ion-trap mass analyzers despite their duty cycle mismatch. Traditionally, FT-IMS experiments have been carried out to utilize continuous linear frequency sweeps that are independent of the scan rate of the ion-trap mass analyzer, thus creating a situation where multiple frequencies are swept over two sequential mass scans. This in turn creates a degree of ambiguity in which the ion current derived from a single modulation frequency cannot be assigned to a single data point in the frequency-modulated signal. In an effort to eliminate this ambiguity, this work describes a discrete stepwise function to modulate the ion gates of the IMS while synchronization between the generated frequencies and the scan rate of the linear ion trap is achieved. While the number of individual frequencies used in the stepped frequency sweeps is less than in continuous linear modulation experiments, there is no loss in performance and high levels of precision are maintained across differing combinations of terminal frequencies and scan lengths. Furthermore, the frequency-scan synchronization enables further data-processing techniques such as linear averaging of the frequency modulated signal to drastically improve signal-to-noise ratio for both high and low intensity analytes.

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Determination of Gas-Phase Ion Mobility Coefficients Using Voltage Sweep Multiplexing

Cited by 20 publications

References 47 publications

Analyzing Positive Reactant Ions in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS) by HiKE-IMS–MS

Analyzing Positive Reactant Ions in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS) by HiKE-IMS–MS

Ion Mobility Spectrometry with High Ion Utilization Efficiency Using Traveling Wave-Based Structures for Lossless Ion Manipulations

Synchronized Stepped Frequency Modulation for Multiplexed Ion Mobility Measurements

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