High-Resolution High Kinetic Energy Ion Mobility Spectrometer Based on a Low-Discrimination Tristate Ion Shutter

Kirk, Ansgar T.; Grube, Denise; Kobelt, Tim; Wendt, Cornelius; Zimmermann, Stefan

doi:10.1021/acs.analchem.7b04586

Cited by 75 publications

(142 citation statements)

References 33 publications

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“…While the B–N gate has been the workhorse of commercial and research instruments for many years, there are well-known limitations associated with the short injection times required to push the resolving power beyond 100. 21 , 53 − 55 To the best of our knowledge, all of the ultrahigh-resolution systems reported for DT-IMS have used a field switching gate rather than a B–N gate.…”

Section: Resultsmentioning

confidence: 99%

Flexible Drift Tube for High Resolution Ion Mobility Spectrometry (Flex-DT-IMS)

et al. 2020

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This paper describes, in detail, the development of a novel, low-cost, and flexible drift tube (DT) along with an associated ion mobility spectrometer system. The DT is constructed from a flexible printed circuit board (PCB), with a bespoke “dog-leg” track design, that can be rolled up for ease of assembly. This approach incorporates a shielding layer, as part of the flexible PCB design, and represents the minimum dimensional footprint conceivable for a DT. The low thermal mass of the polyimide substrate and overlapping electrodes, as afforded by the dog-leg design, allow for efficient heat management and high field linearity within the tube–achieved from a single PCB. This is further enhanced by a novel double-glazing configuration which provides a simple and effective means for gas management, minimizing thermal variation within the assembly. Herein, we provide a full experimental characterization of the flexible DT ion mobility spectrometer (Flex-DT-IMS) with corresponding electrodynamic (Simion 8.1) and fluid dynamic (SolidWorks) simulations. The Flex-DT-IMS is shown to have a resolution >80 and a detection limit of low nanograms for the analysis of common explosives (RDX, PETN, HMX, and TNT).

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Section: Resultsmentioning

confidence: 99%

Flexible Drift Tube for High Resolution Ion Mobility Spectrometry (Flex-DT-IMS)

et al. 2020

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“…A detailed description of the HiKE‐IMS setup was previously provided by Kirk et al 24 The operating parameters used in this work are presented in Table 1. To identify individual ion species associated with signals in the ion mobility spectrum, the HiKE‐IMS‐MS coupling described in a previous work 21 is used.…”

Section: Methodsmentioning

confidence: 99%

Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Allers

Kirk

Schaefer

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale: Ion mobility spectrometry (IMS) instruments are typically equipped with atmospheric pressure chemical ionization (APCI) sources operated at ambient pressure. However, classical APCI-IMS suffers from a limited ionization yield for nonpolar substances with low proton affinity (PA). This is mainly due to ion clustering processes, especially those that involve water molecules, inhibiting the ionization of these substances. Methods: High Kinetic Energy (HiKE)-IMS instruments are operated at decreased pressures and high reduced electric field strengths. As most clustering reactions are inhibited under these conditions, the ionization yield for nonpolar substances with low PA in HiKE-IMS should differ from that in classical APCI-IMS. To gain first insights into the ionization capabilities and limitations of HiKE-IMS, we investigated the ionization of four model substances with low PA in HiKE-IMS using HiKE-IMS-MS as a function of the reduced electric field strength. Results: The four model substances all have proton affinities between those of H 2 O and (H 2 O) 2 but exhibit different ionization energies, dipole moments, and polarizabilities. As expected, the results show that the ionization yield for these substances differs considerably at low reduced electric field strengths due to ion cluster formation. In contrast, at high reduced electric field strengths, all substances can be ionized via charge and/or proton transfer in HiKE-IMS. Conclusions: Considering the detection of polar substances with high PAs, classical ambient pressure IMS should reach better detection limits than HiKE-IMS. However, considering the detection of nonpolar substances with low PA that are not detected, or only difficult to detect, at ambient pressure, HiKE-IMS would be beneficial. 1 | INTRODUCTION Due to their high sensitivity, fast response times, and compact design, ion mobility spectrometers are commonly used in safety and security applications such as the detection of chemical warfare agents, 1,2 toxic industrial chemicals, 3,4 drugs, 5,6 and explosives. 7-9 Basically, ion mobility spectrometry (IMS) instruments can be divided by their principle of ion separation. In this work, a drift tube (DT) ion mobility spectrometer is used. In DT-IMS, ions are separated by their motion along the axis of a drift tube driven by a homogeneous static electric field. To initiate the measurement, an ion packet is injected into the drift tube. During their motion, the ions are separated based on the absolute value of their ion mobility in the present drift gas. At the end of the drift tube, the ions are captured by a detector that converts

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“…This agrees well with the experimental results of Tabrizchi et al [1] and An et al [14], who both observed a quadratic increase in ion current with increasing applied voltage. Third, in HiKE-IMS, where the reduced field strength E/N is an experimental parameter used to control the ion chemistry, the pressure inside the device is inversely proportional to the length at a constant available voltage [15]. Thus, reducing the length and increasing the pressure in HiKE-IMS would result in a quadratically increasing ion current at the same reduced field strength E/N.…”

Section: Analytical Modelmentioning

confidence: 99%

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

Kirk

Kobelt

Spehlbrink

et al. 2018

J. Am. Soc. Mass Spectrom.

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Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region. Graphical Abstract ᅟ.

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High-Resolution High Kinetic Energy Ion Mobility Spectrometer Based on a Low-Discrimination Tristate Ion Shutter

Cited by 75 publications

References 33 publications

Flexible Drift Tube for High Resolution Ion Mobility Spectrometry (Flex-DT-IMS)

Flexible Drift Tube for High Resolution Ion Mobility Spectrometry (Flex-DT-IMS)

Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

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