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Reinecke T, Kenyon S, Gendreau K, Clowers BH. Characterization of a Modulated X-ray Source for Ion Mobility Spectrometry. Anal Chem 2022; 94:12008-12015. [PMID: 36001409 DOI: 10.1021/acs.analchem.2c00729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As a highly deployed field instrument for the detection of narcotics, explosives, and chemical warfare agents, drift tube ion mobility spectrometry relies heavily upon the performance of the ionization source and mechanism of ion beam modulation. For this instrumental platform, ion chemistry plays a critical role in the performance of the instrument from a sensitivity and selectivity perspective; however, a range of instrumental components also occupy pivotal roles. Most notably, the mechanism of ion modulation or ion gating is a primary contributor to peak width in a drift tube ion mobility experiment. Unfortunately, physical ion gates rarely perform perfectly, and in addition to serving as physical impediments to ion transmission, their modulation also has undesirable field effects. Using a recently developed modulated, non-radioactive X-ray source, we detail the performance of an ion mobility spectrometry (IMS) system that is free of a gating structure and utilizes the pulsed nature of the modulated X-ray source (MXS) for both ion generation and initiation of the IMS experiment. After investigating the influence of pulse duration and spatial X-ray beam width on the analytical performance of the instrument, the possibility of using multiplexing with a shutterless system is explored. By increasing ion throughput, the observed multiplexing gain compared to a signal-averaged spectrum approaches the theoretical maximum and illustrates the capability of the MXS-IMS system to realize significant signal to noise improvements.
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Affiliation(s)
- Tobias Reinecke
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Steven Kenyon
- National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland 20771, United States
| | - Keith Gendreau
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Brian H Clowers
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
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Bunert E, Bernhold B, Woidtke JN, Sehlmeyer M, Zimmermann S. Non-radioactive electron capture detector for gas chromatography - A possible replacement for radioactive detectors. J Chromatogr A 2019; 1606:460384. [PMID: 31371199 DOI: 10.1016/j.chroma.2019.460384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/25/2019] [Accepted: 07/17/2019] [Indexed: 11/17/2022]
Abstract
With detection limits in the low ppbv-range, electron capture detectors (ECD) are the most sensitive GC-detectors available for electron affine compounds, such as pesticides or chlorofluorocarbons. The working principle is based on the generation of free electrons at atmospheric pressure, which are usually emitted from a radioactive Ni-63 source. However, the use of radioactive materials leads to regulatory restrictions regarding purchase, operation and disposal. Recently, we introduced a novel ECD based on a non-radioactive electron source, achieving comparable detection limits, e.g. 1 ppbv (6 ng/l) for 1,1,2-trichloroethane. However, the linear range was still below that of radioactive ECDs. In addition, the detector volume was too large to be used as a GC detector. We now present an improved version of this non-radioactive ECD with significantly increased linear range of 6.5∙103 for 1,1,2-trichloroethane by implementing pulsed operation using a newly developed, autonomous control electronics. In addition, the detector volume is reduced to 100 μl, leading to faster response times, less memory effects and thus less peak broadening. The improved ECD with non-radioactive electron source reaches similar analytical performance compared to commercially available radioactive ECDs and thus can be used as a possible replacement of radioactive ECDs.
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Affiliation(s)
- Erik Bunert
- Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Appelstr. 9A, 30167 Hannover, Germany.
| | - Birger Bernhold
- Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Appelstr. 9A, 30167 Hannover, Germany
| | - Jan N Woidtke
- Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Appelstr. 9A, 30167 Hannover, Germany
| | - Merle Sehlmeyer
- Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Appelstr. 9A, 30167 Hannover, Germany
| | - Stefan Zimmermann
- Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Appelstr. 9A, 30167 Hannover, Germany
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Bunert E, Berger M, Kirk AT, Zimmermann S. Non-radioactive electron source with nanosecond pulse modulation for atmospheric pressure chemical ionization. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:113306. [PMID: 31779458 DOI: 10.1063/1.5126507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
Ion mobility spectrometers (IMSs) are well-known instruments for fast and ultrasensitive trace gas detection. In recent years, we introduced a compact nonradioactive electron source providing a defined current of free electrons with high kinetic energy at atmospheric pressure for initiating a chemical gas phase ionization of the analytes identical to radioactive sources. Besides its nonradioactivity, one major advantage of this electron source is its controlled electron emission current even in pulsed mode. By optimizing the geometric parameters and developing faster control electronics, we now achieve electron pulses with extremely short pulse widths down to 23 ns. This allows us to kinetically control the formation of reactants and analyte ions by chemical gas phase ionization (e.g., reducing discrimination processes caused by competing ionization), enhancing the analytical performance of the IMS. However, this paper concentrates on the pulsed electron source. For its characterization, we developed a measurement setup, which allows the detection of nanosecond electron pulses with amplitudes of only a few nanoamperes. Furthermore, we investigated the spatial ion distribution in the ionization region depending on several operating parameters, such as the kinetic electron energy or the ionization time.
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Affiliation(s)
- Erik Bunert
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, 30167 Hannover, Germany
| | - Marc Berger
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, 30167 Hannover, Germany
| | - Ansgar T Kirk
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, 30167 Hannover, Germany
| | - Stefan Zimmermann
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, 30167 Hannover, Germany
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Bunert E, Kirk AT, Käbein O, Zimmermann S. Comparison of spatial ion distributions from different ionization sources. ACTA ACUST UNITED AC 2018. [DOI: 10.1007/s12127-018-0241-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Bunert E, Reinecke T, Kirk AT, Bohnhorst A, Zimmermann S. Ion mobility spectrometer with orthogonal X-Ray source for increased sensitivity. Talanta 2018; 185:537-541. [DOI: 10.1016/j.talanta.2018.04.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 03/29/2018] [Accepted: 04/08/2018] [Indexed: 11/27/2022]
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Bunert E, Heptner A, Reinecke T, Kirk AT, Zimmermann S. Shutterless ion mobility spectrometer with fast pulsed electron source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:024102. [PMID: 28249507 DOI: 10.1063/1.4976021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ion mobility spectrometers (IMS) are devices for fast and very sensitive trace gas analysis. The measuring principle is based on an initial ionization process of the target analyte. Most IMS employ radioactive electron sources, such as 63Ni or 3H. These radioactive materials have the disadvantage of legal restrictions and the electron emission has a predetermined intensity and cannot be controlled or disabled. In this work, we replaced the 3H source of our IMS with 100 mm drift tube length with our nonradioactive electron source, which generates comparable spectra to the 3H source. An advantage of our emission current controlled nonradioactive electron source is that it can operate in a fast pulsed mode with high electron intensities. By optimizing the geometric parameters and developing fast control electronics, we can achieve very short electron emission pulses for ionization with high intensities and an adjustable pulse width of down to a few nanoseconds. This results in small ion packets at simultaneously high ion densities, which are subsequently separated in the drift tube. Normally, the required small ion packet is generated by a complex ion shutter mechanism. By omitting the additional reaction chamber, the ion packet can be generated directly at the beginning of the drift tube by our pulsed nonradioactive electron source with only slight reduction in resolving power. Thus, the complex and costly shutter mechanism and its electronics can also be omitted, which leads to a simple low-cost IMS-system with a pulsed nonradioactive electron source and a resolving power of 90.
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Affiliation(s)
- E Bunert
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hannover, Germany
| | - A Heptner
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hannover, Germany
| | - T Reinecke
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hannover, Germany
| | - A T Kirk
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hannover, Germany
| | - S Zimmermann
- Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hannover, Germany
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Heptner A, Angerstein N, Reinecke T, Bunert E, Kirk AT, Niedzwiecki I, Zimmermann S. Improving the analytical performance of ion mobility spectrometer using a non-radioactive electron source. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/s12127-016-0205-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Liedtke S, Ahlmann N, Marggraf U, Schütz A, Vautz W, Franzke J. Medium Vacuum Electron Emitter as Soft Atmospheric Pressure Chemical Ionization Source for Organic Molecules. Anal Chem 2016; 88:5003-8. [DOI: 10.1021/acs.analchem.6b01164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sascha Liedtke
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
| | - Norman Ahlmann
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
| | - Ulrich Marggraf
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
| | - Alexander Schütz
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
| | - Wolfgang Vautz
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
| | - Joachim Franzke
- Leibniz-Institut für Analytische
Wissenschaften, Bunsen-Kirchhoff-Strassw
11, 44139 Dortmund, Germany
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