A low activity ion source for measurement of atmospheric gases by CIMS

Abstract. Most I--CIMS (iodide-chemical ionization mass spectrometers) for measurement of atmospheric trace gases utilize a radioactive ion source with an initial activity of 10 or 20 mCi of 210Po. In this work, we characterize a 210Po ion source with an initial activity of 1.5 mCi that can be easily constructed from commercially available components. The low level of radioactive activity of this source significantly reduces complications with storage and shipping relative to higher activity sources. We compare the sensitivity of the low activity source (LAS) to a standard 20 mCi source, as a function of carrier gas flow and flow tube pressure, for peroxyacetyl nitrate (PAN), formic acid (HCO2H) molecular chlorine (Cl2), and nitryl chloride (ClNO2) using an I--CIMS. The LAS provides 2 to 5 times less sensitivity than that of the standard source even though the ratio of activity is approximately 13. However, detection limits of less than 2 pptv for the tested compounds are achieved for integration times of the order of a minute. The sensitivity of the LAS is less dependent on the magnitude of the carrier gas than a standard source. In addition, the LAS provides maximum sensitivity at relatively low carrier gas flows. Finally, we demonstrate that the LAS can be used to measure PAN in the remote atmosphere from an aircraft by showing data obtained on the NASA DC-8 during the Atmospheric Tomography (ATom) mission. In summary, the LAS may be an excellent substitute for a standard ion source in some field applications.

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A low-activity ion source for measurement of atmospheric gases by chemical ionization mass spectrometry

Atmospheric Measurement Techniques ◽

10.5194/amt-13-2473-2020 ◽

2020 ◽

Vol 13 (5) ◽

pp. 2473-2480 ◽

Cited By ~ 1

Author(s):

Young Ro Lee ◽

Yi Ji ◽

David J. Tanner ◽

L. Gregory Huey

Keyword(s):

Gas Flow ◽

Chemical Ionization ◽

Ion Source ◽

Ionization Mass ◽

Gas Flows ◽

Initial Activity ◽

Mass Spectrometers ◽

Carrier Gas ◽

Standard Source ◽

Low Activity

Abstract. Most I−-CIMSs (iodide chemical ionization mass spectrometers) for measurement of atmospheric trace gases utilize a radioactive ion source with an initial activity of 10 or 20 mCi of 210Po. In this work, we characterize a 210Po ion source with an initial activity of 1.5 mCi that can be easily constructed from commercially available components. The low level of radioactive activity of this source significantly reduces regulatory burden with storage and shipping relative to higher-activity sources. We compare the sensitivity of the low-activity source (LAS) to a standard 20 mCi source, as a function of carrier gas flow and flow tube pressure, for peroxyacetyl nitrate (PAN), formic acid (HCO2H), molecular chlorine (Cl2) and nitryl chloride (ClNO2), using an I−-CIMS. The LAS provides 2 to 5 times less sensitivity than that of the standard source even though the ratio of activity is approximately 13. However, detection limits of less than 2 pptv for the tested compounds are achieved for integration times on the order of a minute. The sensitivity of the LAS is less dependent on the magnitude of the carrier gas than a standard source. In addition, the LAS provides maximum sensitivity at relatively low carrier gas flows. Finally, we demonstrate that the LAS can be used to measure PAN in the remote atmosphere from an aircraft by showing data obtained on the NASA DC-8 during the Atmospheric Tomography (ATom) mission. In summary, the LAS may be an excellent substitute for a standard ion source in short-term field deployments.

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Experimental Strategies for Avoiding Saturation Effects in ESI-MS

10.26434/chemrxiv.8872487 ◽

2019 ◽

Author(s):

Alan Wei ◽

Anuj Joshi ◽

Yuxuan Chen ◽

J Scott McIndoe

Keyword(s):

Mass Spectrometry ◽

Gas Flow ◽

High Sensitivity ◽

Ionization Mass ◽

High Concentration ◽

Mass Spectrometers ◽

Esi Ms ◽

Processing Strategies ◽

Saturation Effects ◽

Experimental Strategies

<p>All instruments with detectors are prone to saturation effects at high concentration, and mass spectrometers are no exception. The very high sensitivity of mass spectrometry makes the onset of saturation occur at lower concentrations than other methods, and in cases where the analyte of interest is very reactive, concentrations at which saturation can be problematic may be necessary in order to ensure decomposition is mitigated. Indications that saturation is occurring are provided, and some data processing strategies are outlined, followed by a range of detuning strategies that may be employed to reduce saturation effects in the context of electrospray ionization mass spectrometry (ESI-MS), including lowering voltages on detector or capillary, increasing cone gas flow rates, or adjusting the probe position. A combination of strategies generally allows researchers to make the best possible compromises when studying compounds at relatively high concentration.</p>

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Experimental Strategies for Avoiding Saturation Effects in ESI-MS

10.26434/chemrxiv.8872487.v1 ◽

2019 ◽

Author(s):

Alan Wei ◽

Anuj Joshi ◽

Yuxuan Chen ◽

J Scott McIndoe

Keyword(s):

Mass Spectrometry ◽

Gas Flow ◽

High Sensitivity ◽

Ionization Mass ◽

High Concentration ◽

Mass Spectrometers ◽

Esi Ms ◽

Processing Strategies ◽

Saturation Effects ◽

Experimental Strategies

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Observation of charged droplets from electrospray ionization (ESI) plumes in API mass spectrometers

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03452-y ◽

2021 ◽

Author(s):

Clara Markert ◽

Marco Thinius ◽

Laura Lehmann ◽

Chris Heintz ◽

Florian Stappert ◽

...

Keyword(s):

Electrospray Ionization ◽

Mass Spectrometer ◽

Strong Electric Field ◽

Ion Source ◽

Mass Analyzer ◽

Ionization Mass ◽

Inlet System ◽

Mass Spectrometers ◽

Charged Droplets ◽

Pass Through

AbstractElectrospray ionization (ESI) generates bare analyte ions from charged droplets, which result from spraying a liquid in a strong electric field. Experimental observations available in the literature suggest that at least a significant fraction of the initially generated droplets remain large, have long lifetimes, and can thus aspirate into the inlet system of an atmospheric pressure ionization mass spectrometer (API-MS). We report on the observation of fragment signatures from charged droplets penetrating deeply the vacuum stages of three commercial mass spectrometer systems with largely different ion source and spray configurations. Charged droplets can pass through the ion source and pressure reduction stages and even into the mass analyzer region. Since droplet signatures were found in all investigated instruments, the incorporation of charged droplets is considered a general phenomenon occurring with common spray conditions in ESI sources.

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Supplementary material to "A low activity ion source for measurement of atmospheric gases by CIMS"

10.5194/amt-2019-452-supplement ◽

2019 ◽

Author(s):

Young Ro Lee ◽

Yi Ji ◽

David J. Tanner ◽

L. Gregory Huey

Keyword(s):

Ion Source ◽

Atmospheric Gases ◽

Supplementary Material ◽

Low Activity

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Coupling of planar chromatography with Direct Analysis in Real Time mass spectrometry

Open Chemistry ◽

10.2478/s11532-012-0025-2 ◽

2012 ◽

Vol 10 (3) ◽

pp. 703-710 ◽

Cited By ~ 13

Author(s):

Gertrud Morlock ◽

Elena Chernetsova

Keyword(s):

Mass Spectrometry ◽

Real Time ◽

Gas Flow ◽

Direct Analysis ◽

Ion Source ◽

Ionization Mass ◽

Planar Chromatography ◽

Ionization Source ◽

Desorption Ionization ◽

Developing Area

AbstractDirect Analysis in Real Time mass spectrometry (DART-MS) is an emerging and rapidly developing area of ambient desorption ionization mass spectrometric techniques. Its coupling with planar chromatography is especially promising, as compared to other ambient desorption ionization techniques, because it does not require the use of liquids that may distort the shape of a spot by diffusion effects. In the first publications on TLC/HPTLC-DART-MS, due to the fixed, horizontally aligned supply of the gas flow from the DART ionization source to the MS inlet, the introduction of HPTLC/TLC plates as cut strips was inconvenient for quantitation, and the repeatability was very low due to the manual positioning. Recently a new version of the DART ion source was suggested, which allows adjusting the angle of the DART gas stream and the use of a motorized rail, thereby, improving highly the capabilities of TLC/HPTLC-DART-MS. This comprehensive review describes the development and analytical capabilities of TLC/HPTLC-DART-MS, and the general DART-MS perspectives for surface analysis or imaging MS.

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