1
|
Derpmann V, Müller D, Haack A, Wissdorf W, Kersten H, Benter T. Charging Effects in Inlet Capillaries. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1678-1691. [PMID: 36001770 DOI: 10.1021/jasms.2c00130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Glass or metal inlet capillaries are commonly used for flow restriction in atmospheric pressure ionization mass spectrometers. They exhibit a high ion transmission rate and stability at most operating conditions. However, transferring unipolar currents of ions through inlet capillaries can lead to sudden signal dropouts or drifts of the signal intensity, particularly when materials of different conductivity are in contact with the capillary duct. Molecular layers of water and other gases such as liquid chromatography solvents always form on the surfaces of inlet capillaries at atmospheric pressure ionization conditions. These surface layers play a major role in ion transmission and the occurrence of charging effects, as ions adsorb on the capillary walls as well, charging the walls to electric potentials of up to kilovolts and eventually leading to a hindrance of ion transport into or through the capillary duct. In this work, surface charging effects are reported in dependence on the capillary material, i.e., borosilicate glass, (reduced) lead silicate, quartz, and metal. Low electrical conductance materials show a more pronounced long-term signal drift (e.g., quartz), while higher electrical conductance materials lead to stable long-term behavior.
Collapse
Affiliation(s)
- Valerie Derpmann
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| | - David Müller
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| | - Alexander Haack
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| | - Walter Wissdorf
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| | - Hendrik Kersten
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| | - Thorsten Benter
- Physical and Theoretical Chemistry, University of Wuppertal, Gausstrasse 20, 42119 Wuppertal, Germany
| |
Collapse
|
2
|
Analysis of steroids in urine by gas chromatography-capillary photoionization-tandem mass spectrometry. J Chromatogr A 2019; 1598:175-182. [PMID: 31003716 DOI: 10.1016/j.chroma.2019.03.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 03/18/2019] [Accepted: 03/28/2019] [Indexed: 01/19/2023]
Abstract
A new heated capillary photoionization (CPI) ion source design was developed to photoionize analytes inside a transfer capillary between a gas chromatograph (GC) and a mass spectrometer (MS). The CPI setup included a wide, oval-shaped vacuum-ultraviolet (VUV) transparent magnesium fluoride (MgF2) window to maximize photoionization efficiency and thus sensitivity. The source contained a nitrogen housing around the ionization chamber inlet to avoid undesirable hydrolysis and oxidation reactions with ambient air and to maximize the proportion of formed molecular radical cations of analytes. The feasibility of the ion source was studied by analyzing 18 endogenous steroids in urine as their trimethylsilyl (TMS) derivatives with gas chromatography-tandem mass spectrometry (GC-MS/MS). The method was validated and applied to human urine samples. To our best knowledge, this is the first time that a capillary photoionization ion source has been applied for quantitative analysis of biological samples. The GC-CPI-MS/MS method showed good chromatographic resolution (peak half-widths between 3.1 to 5.3 s), acceptable linearity (coefficient of determination between 0.981 to 0.996), and repeatability (relative standard deviation (RSD%) between 5 to 18%). Limits of detection (LOD) were between 2 to 100 pg mL-1 and limits of quantitation (LOQ) were between 0.05 to 2 ng mL-1. In total, 15 steroids were quantified either as a free steroid or glucuronide conjugate from the urine of volunteers. The new CPI source design showed excellent sensitivity for analysis of steroids in complex biological samples.
Collapse
|
3
|
Revel’skii IA, Yashin YS, Revel’skii AI. Atmospheric Pressure Photoionization Mass Spectrometry: New Capabilities for the Determination of the Numbers of Components in Complex Mixtures and Their Identification. JOURNAL OF ANALYTICAL CHEMISTRY 2019. [DOI: 10.1134/s1061934819020102] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
4
|
Di Lorenzo RA, Lobodin VV, Cochran J, Kolic T, Besevic S, Sled JG, Reiner EJ, Jobst KJ. Fast gas chromatography-atmospheric pressure (photo)ionization mass spectrometry of polybrominated diphenylether flame retardants. Anal Chim Acta 2019; 1056:70-78. [PMID: 30797463 DOI: 10.1016/j.aca.2019.01.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/24/2018] [Accepted: 01/07/2019] [Indexed: 12/15/2022]
Abstract
Gas chromatography (GC) and mass spectrometry (MS) are powerful, complementary techniques for the analysis of environmental toxicants. Currently, most GC-MS instruments employ electron ionization under vacuum, but the concept of coupling GC to atmospheric pressure ionization (API) is attracting revitalized interest. API conditions are inherently compatible with a wide range of ionization techniques as well high carrier gas flows that enable fast GC separations. This study reports on the application of atmospheric pressure chemical ionization (APCI) and a custom-built photoionization (APPI) source for the GC-MS analysis of polybrominated diphenyl ethers (PBDEs), a ubiquitous class of flame retardants. Photoionization of PBDEs resulted in the abundant formation of molecular ions M•+ with very little fragmentation. Some photo-oxidation was observed, which differentiated critical BDE isomers. Formation of protonated molecules [M+H]+ did not occur in GC-APPI because the ionization energy of H2O (clusters) exceeds the energy of the ionizing photons. Avoiding mixed-mode ionization is a major advantage of APPI over APCI, which requires careful control of the source conditions. A fast GC-API-MS method was developed using helium and nitrogen carrier gases that provides good separation of critical isomers (BDE-49/71) and elution of BDE 209 in less than 7 min (with He) and 15 min (with N2). It will be shown that the GC-APPI and GC-APCI methods match the sensitivity and improve upon the selectivity and throughput of established methods for the analysis of PBDEs using standard reference materials (NIST SRM 1944 and SRM 2585) and selected environmental samples.
Collapse
Affiliation(s)
- Robert A Di Lorenzo
- Mouse Imaging Centre, The Hospital for Sick Children, 25 Orde Street, Toronto, ON, M5T 3H7, Canada
| | - Vladislav V Lobodin
- National High Magnetic Field Laboratory, Florida State University, 1800 E Paul Dirac Dr., Tallahassee, FL, 32310, USA.
| | - Jack Cochran
- VUV Analytics, 715 Discovery Blvd. Suite 502, Cedar Park, TX, 78613, USA
| | - Terry Kolic
- Ontario Ministry of the Environment, Conservation and Parks, 125 Resources Road, Toronto, Ontario, M9P 3V6, Canada
| | - Sladjana Besevic
- Ontario Ministry of the Environment, Conservation and Parks, 125 Resources Road, Toronto, Ontario, M9P 3V6, Canada
| | - John G Sled
- Mouse Imaging Centre, The Hospital for Sick Children, 25 Orde Street, Toronto, ON, M5T 3H7, Canada
| | - Eric J Reiner
- Ontario Ministry of the Environment, Conservation and Parks, 125 Resources Road, Toronto, Ontario, M9P 3V6, Canada; Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON, M5S 3H6, Canada
| | - Karl J Jobst
- Ontario Ministry of the Environment, Conservation and Parks, 125 Resources Road, Toronto, Ontario, M9P 3V6, Canada; Department of Chemistry and Chemical Biology, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4M1, Canada.
| |
Collapse
|
5
|
Pöhö P, Vaikkinen A, Haapala M, Kylli P, Kostiainen R. Capillary photoionization: interface for low flow rate liquid chromatography-mass spectrometry. Analyst 2019; 144:2867-2871. [DOI: 10.1039/c9an00258h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The first report on capillary photoionization interfacing a liquid chromatograph and mass spectrometer.
Collapse
Affiliation(s)
- Päivi Pöhö
- Drug Research Program
- Division of Pharmaceutical Chemistry and Technology
- Faculty of Pharmacy
- University of Helsinki
- 00014 Finland
| | - Anu Vaikkinen
- Drug Research Program
- Division of Pharmaceutical Chemistry and Technology
- Faculty of Pharmacy
- University of Helsinki
- 00014 Finland
| | - Markus Haapala
- Drug Research Program
- Division of Pharmaceutical Chemistry and Technology
- Faculty of Pharmacy
- University of Helsinki
- 00014 Finland
| | - Petri Kylli
- Drug Research Program
- Division of Pharmaceutical Chemistry and Technology
- Faculty of Pharmacy
- University of Helsinki
- 00014 Finland
| | - Risto Kostiainen
- Drug Research Program
- Division of Pharmaceutical Chemistry and Technology
- Faculty of Pharmacy
- University of Helsinki
- 00014 Finland
| |
Collapse
|
6
|
Mirabelli MF, Zenobi R. Solid-Phase Microextraction Coupled to Capillary Atmospheric Pressure Photoionization-Mass Spectrometry for Direct Analysis of Polar and Nonpolar Compounds. Anal Chem 2018. [DOI: 10.1021/acs.analchem.7b04514] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Mario F. Mirabelli
- ETH Zurich, Department of Chemistry and Applied Biosciences, 8093 Zurich, Switzerland
| | - Renato Zenobi
- ETH Zurich, Department of Chemistry and Applied Biosciences, 8093 Zurich, Switzerland
| |
Collapse
|
7
|
Kauppila TJ, Syage JA, Benter T. Recent developments in atmospheric pressure photoionization-mass spectrometry. MASS SPECTROMETRY REVIEWS 2017; 36:423-449. [PMID: 25988849 DOI: 10.1002/mas.21477] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 04/29/2015] [Indexed: 05/28/2023]
Abstract
Recent developments in atmospheric pressure photoionization (APPI), which is one of the three most important ionization techniques in liquid chromatography-mass spectrometry, are reviewed. The emphasis is on the practical aspects of APPI analysis, its combination with different separation techniques, novel instrumental developments - especially in gas chromatography and ambient mass spectrometry - and the applications that have appeared in 2009-2014. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:423-449, 2017.
Collapse
Affiliation(s)
- Tiina J Kauppila
- Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Finland
| | - Jack A Syage
- Morpho Detection, 1251 E. Dyer Rd., Santa Ana, CA 92705, USA
| | - Thorsten Benter
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaußstr. 20, 42119 Wuppertal, Germany
| |
Collapse
|
8
|
Li Z, Xu C, Shu J. Detection of sub-pptv benzene, toluene, and ethylbenzene via low-pressure photoionization mass spectrometry. Anal Chim Acta 2017; 964:134-141. [PMID: 28351629 DOI: 10.1016/j.aca.2017.01.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 01/26/2017] [Accepted: 01/28/2017] [Indexed: 02/03/2023]
Abstract
This paper reports on the advanced development of an ultrasensitive method for the detection of benzene, toluene, and ethylbenzene (or BTE) by low-pressure photoionization mass spectrometry (LPPI-MS). The LPPI source is composed of a laboratory-assembled krypton lamp and a stainless steel cylindrical ionizer. A compact V-shaped mass spectrometer is coupled to the LPPI source with a set of ion immigration optics under dc bias. The fixed standard concentration (FSC) and fixed standard volume (FSV) method are employed to calibrate the sensitivities of the instrument. The corresponding detection sensitivity toward BTE is 4-7 counts/pptv and the 2σ limit of detection (LOD) is 0.5-0.8 part per trillion by volume (pptv). In addition, the measurement accuracy is 95%-105%, and the corresponding precision ranges from 3% to 15% and from 9% to 31% for the FSC and FSV methods, respectively. The stability (standard deviation) of LPPI-MS for a 1 ppbv BTE mixture is less than 0.025 (>12 h). In the detection of BTE, water in ambient air is the most significant interfering factor, leading to the increased background, and inferior LODs of 1-2 pptv for BTE under an RH of ∼90% is observed. Experimental results indicated that LPPI-MS is reliable for the detection of sub-pptv levels of BTE under laboratory conditions.
Collapse
Affiliation(s)
- Zhen Li
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ce Xu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jinian Shu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing, China.
| |
Collapse
|
9
|
Wißdorf W, Müller D, Brachthäuser Y, Langner M, Derpmann V, Klopotowski S, Polaczek C, Kersten H, Brockmann K, Benter T. Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1550-1563. [PMID: 27245455 DOI: 10.1007/s13361-016-1415-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 04/09/2016] [Accepted: 04/19/2016] [Indexed: 06/05/2023]
Abstract
In this work, the characteristics of gas flow in inlet capillaries are examined. Such inlet capillaries are widely used as a first flow restriction stage in commercial atmospheric pressure ionization mass spectrometers. Contrary to the common assumption, we consider the gas flow in typical glass inlet capillaries with 0.5 to 0.6 mm inner diameters and lengths about 20 cm as transitional or turbulent. The measured volume flow of the choked turbulent gas stream in such capillaries is 0.8 L·min(-1) to 1.6 L·min(-1) under typical operation conditions, which is in good agreement to theoretically calculated values. Likewise, the change of the volume flow in dependence of the pressure difference along the capillary agrees well with a theoretical model for turbulent conditions as well as with exemplary measurements of the static pressure inside the capillary channel. However, the results for the volume flow of heated glass and metal inlet capillaries are neither in agreement with turbulent nor with laminar models. The velocity profile of the neutral gas in a quartz capillary with an inner diameter similar to commercial inlet capillaries was experimentally determined with spatially resolved ion transfer time measurements. The determined gas velocity profiles do not contradict the turbulent character of the flow. Finally, inducing disturbances of the gas flow by placing obstacles in the capillary channel is found to not change the flow characteristics significantly. In combination the findings suggest that laminar conditions inside inlet capillaries are not a valid primary explanation for the observed high ion transparency of inlet capillaries under common operation conditions. Graphical Abstract ᅟ.
Collapse
Affiliation(s)
- Walter Wißdorf
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany.
| | - David Müller
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | | | - Markus Langner
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | - Valerie Derpmann
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | | | - Christine Polaczek
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | - Hendrik Kersten
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | - Klaus Brockmann
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| | - Thorsten Benter
- Bergische Universitat Wuppertal, Gaußstraße 20, 42119, Wuppertal, Germany
| |
Collapse
|
10
|
Kauppila TJ, Haack A, Kroll K, Kersten H, Benter T. Nucleophilic Aromatic Substitution Between Halogenated Benzene Dopants and Nucleophiles in Atmospheric Pressure Photoionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:422-431. [PMID: 26637323 DOI: 10.1007/s13361-015-1315-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/12/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
In a preceding work with dopant assisted-atmospheric pressure photoionization (DA-APPI), an abundant ion at [M + 77](+) was observed in the spectra of pyridine and quinoline with chlorobenzene dopant. This contribution aims to reveal the identity and route of formation of this species, and to systematically investigate structurally related analytes and dopants. Compounds containing N-, O-, and S-lone pairs were investigated with APPI in the presence of fluoro-, chloro-, bromo-, and iodobenzene dopants. Computational calculations on a density functional theory (DFT) level were carried out to study the reaction mechanism for pyridine and the different halobenzenes. The experimental and computational results indicated that the [M + 77](+) ion was formed by nucleophilic aromatic ipso-substitution between the halobenzene radical cation and nucleophilic analytes. The reaction was most efficient for N-heteroaromatic compounds, and it was weakened by sterical effects and enhanced by resonance stabilization. The reaction was most efficient with chloro-, bromo-, and iodobenzenes, whereas with fluorobenzene the reaction was scarcely observed. The calculated Gibbs free energies for the reaction between pyridine and the halobenzenes were shown to increase in the order I < Br < Cl < F. The reaction was found endergonic for fluorobenzene due to the strong C-F bonding, and exergonic for the other halobenzenes. For fluoro- and chlorobenzenes the reaction was shown to proceed through an intermediate state corresponding to [M + dopant](+), which was highly stable for fluorobenzene. For the bulkier bromine and iodine, this intermediate did not exist, but the halogens were shown to detach already during the approach by the nucleophile.
Collapse
Affiliation(s)
- Tiina J Kauppila
- Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland.
| | - Alexander Haack
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Kai Kroll
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Hendrik Kersten
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Thorsten Benter
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| |
Collapse
|
11
|
Li DX, Gan L, Bronja A, Schmitz OJ. Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review. Anal Chim Acta 2015; 891:43-61. [DOI: 10.1016/j.aca.2015.08.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 07/20/2015] [Accepted: 08/02/2015] [Indexed: 10/23/2022]
|
12
|
Kauppila TJ, Kersten H, Benter T. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1036-1045. [PMID: 25828352 DOI: 10.1007/s13361-015-1092-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/19/2015] [Accepted: 02/04/2015] [Indexed: 06/04/2023]
Abstract
Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.
Collapse
Affiliation(s)
- Tiina J Kauppila
- Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, 00014, Helsinki, Finland,
| | | | | |
Collapse
|
13
|
Revelsky IA, Tikhonova IN, Yashin YS. Letter: Fast detection of polycyclic aromatic hydrocarbons in complex mixtures of organic compounds based on gas chromatography-mass spectrometry with atmospheric pressure photoionization. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:753-757. [PMID: 26579932 DOI: 10.1255/ejms.1392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The research is devoted to the investigation of the selectivity detection of 16 polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry (GC-MS), electron ionization (EI) GC-MS with atmospheric pressure photoionization (APPhI) and GC-MS atmospheric pressure photochemical ionization (APPhCI) when vapors of different substances (benzene, toluene, and naphthalene) were used as gas reagents. Capillary columns of different lengths were used for the separation of the components of the mixture of 44 semivolatile organic compounds. It was shown that the most-selective detection of 16 PAHs in a 44- component mixture was possible when GC-MS APPhCI was used. Only 16 PAHs were registered on the respective mass chromatograms and a fast detection of them was possible. The respective APPhI and APPhCI mass spectra consisted of only peak of the respective molecular ion, M⁺⁺ - the radical cation. Detection limits were 3 pg μL⁻¹ to 15 pg μL.
Collapse
Affiliation(s)
- Igor A Revelsky
- Lomonosov Moscow State University, Department of Chemistry, Leninskye Gory, 1, building 3, 119992, Moscow, Russia.
| | - I N Tikhonova
- Lomonosov Moscow State University, Department of Chemistry, Leninskye Gory, 1, building 3, 119992, Moscow, Russia
| | - Yu S Yashin
- Lomonosov Moscow State University, Department of Chemistry, Leninskye Gory, 1, building 3, 119992, Moscow, Russia
| |
Collapse
|
14
|
Kauppila TJ, Kersten H, Benter T. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1870-1881. [PMID: 25248413 DOI: 10.1007/s13361-014-0988-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/19/2014] [Accepted: 08/19/2014] [Indexed: 06/03/2023]
Abstract
A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.
Collapse
Affiliation(s)
- Tiina J Kauppila
- Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland,
| | | | | |
Collapse
|
15
|
Klee S, Thinius M, Brockmann KJ, Benter T. Capillary atmospheric pressure chemical ionization using liquid point electrodes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1591-1600. [PMID: 24895256 DOI: 10.1002/rcm.6944] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE Atmospheric pressure chemical ionization (APCI) sources operated with point to plane DC discharges ('Coronas') frequently suffer from point electrode degradation and potentially lead to oxidation and/or fragmentation of the generated analyte ions. It is postulated that these adverse effects are caused by the interaction of these ions with the discharge chemistry as well as en route to the mass analyzer region. METHODS The corona discharge metal point electrode is replaced by the conically shaped liquid effluent evolving from a fused-silica capillary, which is analogous but not identical to the Taylor cone formation in electrospray ionization. The liquid consisting of either pure water or water containing 0.1 %V formic acid is fed via a nano-flow delivery stage at typical flow rates between 1-800 μL/h. The liquid flow is continuously replenishing the surface of the point electrode. The source is directly coupled to the inlet capillary of appropriate mass spectrometers, e.g., the Bruker Daltonics and Agilent varieties. RESULTS The actively pumped liquid flow is supplying a constant amount of the reagent gas (H2O) to the corona region in the 20 ppmV to 30 %V range, leading to controlled, very stable operation of the source. The typical light emission observed for corona discharges is in very close proximity to the aqueous surface. Analyte protonation is the dominating ionization pathway. The degree of primary analyte fragmentation is extremely low. CONCLUSIONS We have developed a novel atmospheric pressure chemical ionization source designed for the hyphenation of nano-flow liquid chromatography and gas chromatography with atmospheric pressure ionization mass spectrometry. The proposed reaction mechanism including the electrochemistry occurring in the source along with formation of protonated analyte molecules via collision-induced dissociation (CID) is in full accord with the experimental results. The system exhibits an extremely stable performance over prolonged operation times, sole generation of protonated molecules, and low degree of analyte ion fragmentation.
Collapse
Affiliation(s)
- Sonja Klee
- Institute for Pure and Applied Mass Spectrometry, Physical and Theoretical Chemistry, University of Wuppertal, Gauß Str. 20, 42119, Wuppertal, Germany
| | | | | | | |
Collapse
|
16
|
Zhu Z, Wang J, Qiu K, Liu C, Qi F, Pan Y. Note: a novel vacuum ultraviolet light source assembly with aluminum-coated electrodes for enhancing the ionization efficiency of photoionization mass spectrometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:046110. [PMID: 24784688 DOI: 10.1063/1.4871796] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A novel vacuum ultraviolet (VUV) light source assembly (VUVLSA) for enhancing the ionization efficiency of photoionization mass spectrometer has been described. The VUVLSA composes of a Krypton lamp and a pair of disk electrodes with circular center cavities. The two interior surfaces that face the photoionization region were aluminum-coated. VUV light can be reflected back and forth in the photoionization region between the electrodes, thus the photoionization efficiency can be greatly enhanced. The performances of two different shaped electrodes, the coated double flat electrodes (DFE), and double conical electrodes, were studied. We showed that the signal amplification of coated DFE is around 4 times higher than that of uncoated electrodes without VUV light reflection. The relationship between the pressure of ionization chamber and mass signal enhancement has also been studied.
Collapse
Affiliation(s)
- Zhixiang Zhu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Jian Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Keqing Qiu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Fei Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| |
Collapse
|
17
|
Derpmann V, Mueller D, Bejan I, Sonderfeld H, Wilberscheid S, Koppmann R, Brockmann KJ, Benter T. Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:329-342. [PMID: 24399666 DOI: 10.1007/s13361-013-0761-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 09/17/2013] [Accepted: 09/24/2013] [Indexed: 06/03/2023]
Abstract
We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.
Collapse
Affiliation(s)
- Valerie Derpmann
- Department of Physical and Theoretical Chemistry, University of Wuppertal, 42119, Wuppertal, Germany,
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Bhardwaj C, Hanley L. Ion sources for mass spectrometric identification and imaging of molecular species. Nat Prod Rep 2014; 31:756-67. [PMID: 24473154 DOI: 10.1039/c3np70094a] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Covering: 2013 The ability to transfer molecular species to the gas phase and ionize them is central to the study of natural products and other molecular species by mass spectrometry (MS). MS-based strategies in natural products have focused on a few established ion sources, such as electron impact and electrospray ionization. However, a variety of other ion sources are either currently in use to evaluate natural products or show significant future promise. This review discusses these various ion sources in the context of other articles in this special issue, but is also applicable to other fields of analysis, including materials science. Ion sources are grouped based on the current understanding of their predominant ion formation mechanisms. This broad overview groups ion sources into the following categories: electron ionization and single photon ionization; chemical ionization-like and plasma-based; electrospray ionization; and, laser desorption-based. Laser desorption-based methods are emphasized with specific examples given for laser desorption postionization sources and their use in the analysis of intact microbial biofilms. Brief consideration is given to the choice of ion source for various sample types and analyses, including MS imaging.
Collapse
Affiliation(s)
- Chhavi Bhardwaj
- Department of Chemistry, University of Illinois at Chicago, mc 111, Chicago, IL 60607-7061.
| | | |
Collapse
|
19
|
Albrecht S, Klopotowski S, Derpmann V, Klee S, Brockmann KJ, Stroh F, Benter T. Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:014102. [PMID: 24517784 DOI: 10.1063/1.4854855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this study a thermally sampling atmospheric pressure ionization mass spectrometer is described and characterized. The ion transfer stage offers the capability to sample cluster ions at thermal equilibrium and during this transfer fundamental processes possibly affecting the cluster distribution are also readily identified. Additionally, the transfer stage combines optional collision-induced dissociation (CID) analysis of the cluster composition with thermal equilibrium sampling of clusters. The performance of the setup is demonstrated with regard to the proton-bound water cluster system. The benefit of the studied processes is that they can help to improve future transfer stages and to understand cluster ion reactions in ion mobility tubes and high-pressure ion sources. In addition, the instrument allows for the identification of fragmentation and protonation reactions caused by CID.
Collapse
Affiliation(s)
- Sascha Albrecht
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich, Germany
| | - Sebastian Klopotowski
- Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal, Germany
| | - Valerie Derpmann
- Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal, Germany
| | - Sonja Klee
- Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal, Germany
| | - Klaus J Brockmann
- Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal, Germany
| | - Fred Stroh
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich, Germany
| | - Thorsten Benter
- Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal, Germany
| |
Collapse
|
20
|
Haapala M, Suominen T, Kostiainen R. Capillary Photoionization: A High Sensitivity Ionization Method for Mass Spectrometry. Anal Chem 2013; 85:5715-9. [DOI: 10.1021/ac4002673] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Markus Haapala
- Division of Pharmaceutical Chemistry,
Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FIN-00014 Viikinkaari
5 E, Finland
| | - Tina Suominen
- Division of Pharmaceutical Chemistry,
Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FIN-00014 Viikinkaari
5 E, Finland
| | - Risto Kostiainen
- Division of Pharmaceutical Chemistry,
Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FIN-00014 Viikinkaari
5 E, Finland
| |
Collapse
|