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Zhu Y, Aliang M, Wang X, Yu Q. Hydrogen-Assisted Photoionization and Its Use in Promoting Mass Spectrometry Analysis of VOCs. Anal Chem 2023; 95:17166-17169. [PMID: 37966263 DOI: 10.1021/acs.analchem.3c04650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
As a simple soft ionization method, photoionization (PI) is often coupled with mass spectrometry (MS) for the direct analysis of volatile organic compounds (VOCs). PI enables selective ionization of analytes, but the ion yield is generally not high due to the limited light intensity of the ultraviolet lamp. Here, a hydrogen-assisted photoionization (HAPI) strategy was developed and integrated into a miniature ion trap mass spectrometer. In particular, hydrogen was introduced as a versatile buffer gas to facilitate both photoionization and ion trap operation. This can increase the ion yields by up to 2 orders of magnitude compared to conventional PI-MS, with a low hydrogen consumption (less than 100 μL) for each analysis. The generation of protonated ions indicates a specific photochemical process in HAPI, which has also been studied and initially revealed. The detection of various VOCs and plant volatile gases confirmed the versatility and practicality of the HAPI technology.
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Affiliation(s)
- Yanping Zhu
- Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Mushage Aliang
- Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Xiaohao Wang
- Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Quan Yu
- Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
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2
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Guo Y, Wang H, Yang B, Shu J, Jiang K, Yu Z, Zhang Z, Li Z, Huang J, Wei Z. An ultrasensitive SPI/PAI ion source based on a high-flux VUV lamp and its applications for the online mass spectrometric detection of sub-pptv sulfur ethers. Talanta 2022; 247:123558. [DOI: 10.1016/j.talanta.2022.123558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/29/2022] [Accepted: 05/14/2022] [Indexed: 10/18/2022]
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3
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Wang W, Jin L, Hu F, Xu F, Ding CF. Nebulization Swab Assisted Photoionization Tandem Miniaturized Ion Trap Mass Spectrometry for On-Site Analysis of Nonvolatile Compounds. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:898-906. [PMID: 35475621 DOI: 10.1021/jasms.2c00048] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nonvolatile compounds usually have a high molecular weight and exhibit a high boiling point, which poses great challenges to the ionization method of MS. Ambient ionization sources can efficiently analyze the nonvolatile compounds without complex pretreatment, but they generally require special media such as heating devices, laser optical devices, or corona needles. Acoustic nebulization assisted photoionization (ANPI) is a potential method for the analysis of nonvolatile compounds that uses nebulization as a prerequisite for photoionization and introduces many advantages of PI, including excellent ionization efficiency, a high yield of molecular ions, and simplified spectrum interpretation. However, the ANPI source can be limited in on-site applications by the complexity of the analytical devices and the high cost of the nebulization chip. To address this issue, in this paper, we explored cheap and commercially piezoelectric materials used in a mist sprayer and fabricated a nebulization swab assisted photoionization (NSAP) as an ambient ionization source. Some useful results are presented: numerical simulation was introduced successfully for optimizing the aerosol distribution in the NSAP source; nonvolatile muscle relaxants, drugs of abuse, antibiotics, phthalates, and cholesterol were detected mostly as their protonated molecular ions while some special acetone/water cluster ions were detected. In addition, the LOD for most of the target analytes ranged from 10.0 to 50.0 pg with RSD ≤ 9%. Finally, this method is implemented for Chinese baijiu spiked with phthalates. The experimental data shows the capability of a NSAP source in high sensitivity and on-site analysis of the nonvolatile compounds.
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Affiliation(s)
- Weimin Wang
- Key Laboratory of Advanced Mass spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China
| | - Liuyu Jin
- Key Laboratory of Advanced Mass spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China
| | - Fengqing Hu
- Department of Cardiothoracic Surgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200000, China
| | - Fuxing Xu
- Key Laboratory of Advanced Mass spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China
| | - Chuan-Fan Ding
- Key Laboratory of Advanced Mass spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China
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4
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Dugan LD, Bier ME. Mechanospray Ionization MS of Proteins Including in the Folded State and Polymers. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:772-782. [PMID: 35420806 DOI: 10.1021/jasms.1c00344] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mechanospray ionization (MoSI) is a technique that produces ions directly from solution-like electrospray ionization (ESI) but without the need of a high voltage. In MoSI, mechanical vibrations aerosolize solution phase analytes, whereby the resulting microdroplets can be directed into the inlet orifice of a mass spectrometer. In this work, MoSI is applied to biomolecules up to 80 kDa in mass in both denatured and native conditions as well as polymers up to 12 kDa in mass. The various MoSI devices used in these analyses were all comprised of a piezoelectric annulus attached to a central metallic disk containing an array of 4 to 7 μm diameter holes. The devices vibrated in the 100-170 kHz range to generate a beam of microdroplets that ultimately resulted in ion formation. A linear quadrupole ion trap (LIT) and orbitrap mass spectrometer were used in the analysis to investigate higher mass proteins at both native (folded) and denatured (unfolded) conditions. MoSI native mass spectra of proteins acquired on the orbitrap and LIT instrument demonstrated that proteins could remain intact and in a folded state. In the case of native MS of holomyoglobin, the intact folded protein remained mostly bound noncovalently to the heme group, and typically, the spectra showed reduced loss of the heme group by MoSI as compared to ESI. In both non-native and native protein analyses examples, broader often multimodal distributions to lower charge states were observed. When using the LIT instrument, a significant increase in the relative abundance of dimers was observed by MoSI as compared to ESI. The softness of the MoSI technique was evidenced by the lack of fragmentation, the formation of dimers as also noted by others ( J. Mass Spectrom. 2016, 424-429) and under native conditions, the retention of proteins in one or more presumed folded structures and for holomyoglobin the high retention of the heme group. When analyzing polyethylene glycol (PEG) and polypropylene glycol (PPG), MoSI also generated a broader distribution to lower charge states than ESI. By using the improved separation of peaks at lower charge states and all the charge states available, MoSI data should provide an improved ionization method to obtain more accurate mass and dispersity values for some polymers.
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Affiliation(s)
- Liam D Dugan
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Mark E Bier
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
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5
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Wu L, Qi K, Xu M, Liu C, Pan Y. Effects of dopants in the imaging of mouse brain by desorption electrospray ionization/post-photoionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4813. [PMID: 35189674 DOI: 10.1002/jms.4813] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/08/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Desorption electrospray ionization/post-photoionization (DESI/PI) is a newly developed ionization method by the combination of DESI and post-photoionization for the simultaneous imaging of polar and nonpolar compounds in biological tissues. Dopants are of great importance in DESI/PI for the enhancement of signal intensities through ion-molecule reactions. In this work, to evaluate the performance of dopants in DESI/PI, an efficient homogenate model was developed, and four kinds of dopants (toluene, chlorobenzene, bromobenzene, and anisole) were tested using homogenate of mouse brain tissue as target sample. The influences of the dopants on the signal enhancements of different compounds were explained reasonably by the ionization mechanism. Then, the dopants with their optimum volume contents were applied to the mass spectrometry imaging (MSI). For a comprehensive imaging of various compounds with different polarities, methanol/toluene/formic acid (7:3:0.1) was chosen as the best choice. Finally, the stronger quantitative ability of DESI/PI with toluene as dopant for a few compounds in mouse brain tissue was demonstrated.
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Affiliation(s)
- Liutian Wu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Keke Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Minggao Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
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6
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Dang M, Liu R, Dong F, Liu B, Hou K. Vacuum ultraviolet photoionization on-line mass spectrometry: instrumentation developments and applications. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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7
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Tang C, Tan J, Fan Y, Peng X. Ascertaining Hydrogen-Abstraction Reaction Efficiencies of Halogenated Organic Compounds in Electron Impact Ionization Processes by Gas Chromatography-High-Resolution Mass Spectrometry. ACS OMEGA 2020; 5:8496-8507. [PMID: 32337410 PMCID: PMC7178364 DOI: 10.1021/acsomega.9b03895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/20/2020] [Indexed: 06/11/2023]
Abstract
H-Abstraction reactions occurring during electron impact ionization processes in electron ionization mass spectrometry (EI-MS) are a long-standing and crucial topic in MS research. Yet, some critical relevant mechanisms are controversial and ambiguous, and information about the EI-induced H-abstraction reactions of halogenated organic compounds (HOCs) is completely in the dark. This study provides a systematic investigation of H-abstraction reactions of HOCs taking place in the EI source using 13C6-hexachlorobenzene (13C6-HCB) and 13C6-hexabromobenzene (13C6-HBB) as exemplary compounds by gas chromatography (GC)-high-resolution mass spectrometry (GC-HRMS). The H-abstraction efficiencies were evaluated with the MS signal intensity ratios of ions with H-abstraction relative to the corresponding original ions (without H-abstraction). Ion source temperatures, EI energies, and numbers of heavy isotope atoms (37Cl or 81Br) of isotopologues were investigated in terms of their effects on the H-abstraction efficiencies. The H-abstraction efficiencies of individual isotopologues generally decreased from the first to the last isotopologues of respective ions, and those of individual ions were different from each other, with the highest values of 0.017 and 0.444 for 13C6-HCB and 13C6-HBB, respectively. The overall H-abstraction efficiencies involving all measured ions of 13C6-HCB and 13C6-HBB were 0.004 and 0.128, respectively. With increasing ion source temperatures, the H-abstraction efficiencies first increased to a summit and then began to linearly decrease. EI energies and emission currents could impact the H-abstraction efficiencies but showed no certain tendency. The H-abstraction reactions were inferred to belong to ion-molecule reactions, and the siloxanes bleeding from the GC column might be a hydrogen source. Some strategies were proposed for eliminating or alleviating the interference triggered by the H-abstraction reactions in EI-MS in identification of halogenated organic pollutants (HOPs). Our findings provide a better understanding of the EI-induced H-abstraction reactions of HOCs and may benefit the identification of HOPs in environmental analysis, especially for novel HOPs.
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Affiliation(s)
- Caiming Tang
- State
Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Jianhua Tan
- Guangzhou
Quality Supervision and Testing Institute, Guangzhou 510110, China
| | - Yujuan Fan
- State
Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Xianzhi Peng
- State
Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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8
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Liu C, Li J, Chen H, Zare RN. Scale-up of microdroplet reactions by heated ultrasonic nebulization. Chem Sci 2019; 10:9367-9373. [PMID: 32110301 PMCID: PMC7017870 DOI: 10.1039/c9sc03701b] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/19/2019] [Indexed: 12/24/2022] Open
Abstract
Dramatically higher rates for a variety of chemical reactions have been reported in microdroplets compared with those in the liquid bulk phase. However, the scale-up of microdroplet chemical synthesis has remained a major challenge to the practical application of microdroplet chemistry. Heated ultrasonic nebulization (HUN) was found as a new way for scaling up chemical synthesis in microdroplets. Four reactions were examined, a base-catalyzed Claisen-Schmidt condensation, an oximation reaction from a ketone, a two-phase oxidation reaction without the use of a phase-transfer-catalyst, and an Eschenmoser coupling reaction. These reactions show acceleration of one to three orders of magnitude (122, 23, 6536, and 62) in HUN microdroplets compared to the same reactions in bulk solution. Then, using the present method, the scale-up of the reactions was achieved at an isolated rate of 19 mg min-1 for the product of the Claisen-Schmidt condensation, 21 mg min-1 for the synthesis of benzophenone oxime from benzophenone, 31 mg min-1 for the synthesis of 4-methoxybenzaldehyde from 4-methoxybenzyl alcohol, and 40 mg min-1 for the enaminone product of the Eschenmoser coupling reaction.
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Affiliation(s)
- Chengyuan Liu
- Department of Chemistry , Fudan University , Shanghai 200438 , China .
| | - Jia Li
- Department of Chemistry , Fudan University , Shanghai 200438 , China .
| | - Hao Chen
- Department of Chemistry & Environmental Science , New Jersey Institute of Technology , Newark , NJ 07102 , USA
| | - Richard N Zare
- Department of Chemistry , Fudan University , Shanghai 200438 , China .
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9
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Ultrasonic Nebulization-Dispersive Solid-Phase-Monolithic Microcolumn Extraction Coupled with HPLC–MS/MS for Analyzing Sex Steroids in Lotion Samples. Chromatographia 2019. [DOI: 10.1007/s10337-019-03797-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Huang J, Yang B, Shu J, Zhang Z, Li Z, Jiang K. Kinetic Understanding of the Ultrahigh Ionization Efficiencies (up to 28%) of Excited-State CH 2Cl 2-Induced Associative Ionization: A Case Study with Nitro Compounds. Anal Chem 2019; 91:5605-5612. [PMID: 30841695 DOI: 10.1021/acs.analchem.8b04813] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Excited-state CH2Cl2-induced associative ionization (AI) is a newly developed ionization method that is very effective for oxygenated organics. However, this method is not widely known. In this study, an unprecedented ionization efficiency and ultrafast reaction rate of AI toward nitro compounds were observed. The ionization efficiencies of o-nitrotoluene (o-NT), m-nitrotoluene (m-NT), and nitrobenzene (NB) were as high as (28 ± 3)%, (27 ± 2)%, and (13 ± 1)%, respectively (∼1-3 ions for every 10 molecules). The measured reaction rate coefficients of these nitroaromatics were (0.5-1.3) × 10-7 molecule-1 cm3 s-1 (∼300 K). These unusual rate coefficients indicated strong long-range interactions between the two neutral reactants, which was regarded as a key factor leading to the ultrahigh ionization efficiency. The detection sensitivities of the nitroaromatics, (1.01-2.16) × 104 counts pptv-1 in 10 s acquisition time, were obtained by an AI time-of-flight mass spectrometer (AI-TOFMS). These experimental results not only provide new insight into the AI reaction but also reveal an excellent ionization method that can improve the detection sensitivity of nitroaromatics to an unprecedented degree.
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Affiliation(s)
- Jingyun Huang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China.,State Key Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
| | - Bo Yang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China
| | - Jinian Shu
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China.,State Key Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
| | - Zuojian Zhang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China.,State Key Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
| | - Zhen Li
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China
| | - Kui Jiang
- National Engineering Laboratory for VOCs Pollution Control Material & Technology , University of Chinese Academy of Sciences , Beijing 101408 , People's Republic of China.,State Key Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
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11
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Liu C, Qi K, Yao L, Xiong Y, Zhang X, Zang J, Tian C, Xu M, Yang J, Lin Z, Lv Y, Xiong W, Pan Y. Imaging of Polar and Nonpolar Species Using Compact Desorption Electrospray Ionization/Postphotoionization Mass Spectrometry. Anal Chem 2019; 91:6616-6623. [PMID: 30907581 DOI: 10.1021/acs.analchem.9b00520] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Desorption electrospray ionization (DESI) mass spectrometry imaging (MSI) can simultaneously record the 2D distribution of polar biomolecules in tissue slices at ambient conditions. However, sensitivity of DESI-MSI for nonpolar compounds is restricted by low ionization efficiency and strong ion suppression. In this study, a compact postphotoionization assembly combined with DESI (DESI/PI) was developed for imaging polar and nonpolar molecules in tissue sections by switching off/on a portable krypton lamp. Compared with DESI, higher signal intensities of nonpolar compounds could be detected with DESI/PI. To further increase the ionization efficiency and transport of charged ions of DESI/PI, the desorption solvent composition and gas flow in the ionization tube were optimized. In mouse brain tissue, more than 2 orders of magnitude higher signal intensities for certain neutral biomolecules like creatine, cholesterol, and GalCer lipids were obtained by DESI/PI in the positive ion mode, compared with that of DESI. In the negative ion mode, ion yields of DESI/PI for glutamine and some lipids (HexCer, PE, and PE-O) were also increased by several-fold. Moreover, nonpolar constituents in plant tissue, such as catechins in leaf shoots of tea, could also be visualized by DESI/PI. Our results indicate that DESI/PI can expand the application field of DESI to nonpolar molecules, which is important for comprehensive imaging of biomolecules in biological tissues with moderate spatial resolution at ambient conditions.
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Affiliation(s)
- Chengyuan Liu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , China
| | - Keke Qi
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , China
| | - Lei Yao
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Ying Xiong
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Xuan Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Jianye Zang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Changlin Tian
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Minggao Xu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , China
| | - Zhenkun Lin
- Center of Scientific Research , The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou 325027 , China
| | - Yongmei Lv
- Department of Dermatology , The Second Affiliated Hospital of Anhui Medical University , Hefei 230601 , China
| | - Wei Xiong
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences , University of Science and Technology of China , Hefei 230026 , China
| | - Yang Pan
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , China
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12
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Ultrasensitive detection of volatile aldehydes with chemi-ionization-coupled time-of-flight mass spectrometry. Talanta 2019; 194:888-894. [PMID: 30609620 DOI: 10.1016/j.talanta.2018.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 10/25/2018] [Accepted: 11/04/2018] [Indexed: 12/20/2022]
Abstract
The chemi-ionization reaction is a high-efficiency pathway to produce molecular ions in plasma, however, it has rarely been applied in mass spectrometry to directly produce analyte ions. In this study, a novel chemi-ionization technique for mass spectrometry was applied for the direct and ultrasensitive detection of gaseous aldehydes. The ionization technique was enacted by a recently observed chemi-ionization reaction: the efficient proton transfer from H2O to oxygenated compounds was stimulated by vacuum ultraviolet (VUV)-excited CH2Cl2. By analyzing a series of aliphatic aldehydes (C2-C5) and benzaldehyde with different proton affinities (PAs) and polarities, the ionization features of the new ionization method were investigated for the first time. The chemi-ionization of aldehydes presented soft ionization characteristics with fragmentation patterns analogous to that of VUV photoionization. The method showed ultrahigh sensitivities toward aldehydes (up to 1108 ± 6 counts pptv-1 for benzaldehyde in 10 s acquisition time). The corresponding 3σ limits of detection (LODs) achieved 0.30-0.69 pptv, which are equivalent of 1.35-1.92 ng m-3, for the compounds investigated. The humidity experiments revealed that the moisture in the sample gas had an evident impact on the detection efficiency of the analyte and the influence was PA dependent. In addition, the applicability of this ionization mode was further tested by analysis of aldehydes in cigarette smoke. This study provides a promising ionization method for greatly improving the current on-line detection sensitivity of volatile aldehydes.
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Liu C, Wen W, Shao J, Zhao W, Qi K, Yang J, Pan Y. Fast and comprehensive characterization of chemical ingredients in traditional Chinese herbal medicines by extractive atmospheric pressure photoionization (EAPPI) mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1491-1498. [PMID: 28667680 DOI: 10.1002/rcm.7929] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 06/18/2017] [Accepted: 06/24/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE The goal of this work is to employ extractive atmospheric pressure photoionization mass spectrometry (EAPPI-MS) to characterize the constituents in traditional Chinese herbal medicine (TCHM) directly without chromatographic separation. METHODS Sample was placed in 4 mL of methanol/water (v/v, 3:1) in the nebulization cell, and then the ultrasonic nebulizer was switched on. The ultrasonic nebulization system allows the simultaneous sample extraction and introduction of extract aerosols. The extract aerosols were vaporized in a transfer tube. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion-molecule reactions, and were mass-analyzed by high-resolution time-of-flight mass spectrometry (TOF-MS). RESULTS The major ingredients including alkaloids, flavonoids, amino acids, saccarides, ginsenosides, lignans and terpenoids were readily detected. Compared with electrospray ionization (ESI), EAPPI allowed the ionization of a wider range of compounds, which is desirable for the integral characterization of TCHMs containing numerous constituents. The significant discrepancies for both alkaloids and terpenoids in tripterygium glycoside tablets from two different manufacturers could be simultaneously reflected from EAPPI mass spectra. CONCLUSIONS Our results demonstrate that EAPPI-MS can be regarded as a supplementary ambient method for the fast and comprehensive analysis of TCHMs, which is important for the quality control and safety assurance of these products.
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Affiliation(s)
- Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
| | - Wu Wen
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
| | - Jun Shao
- The First Affiliated Hospital, Anhui University of Chinese Medicine, Hefei, Anhui, 230031, P.R. China
| | - Wan Zhao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
| | - Keke Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P.R. China
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14
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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.
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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.
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15
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Liu C, Zhu Y, Yang J, Zhao W, Lu D, Pan Y. Effects of Solvent and Ion Source Pressure on the Analysis of Anabolic Steroids by Low Pressure Photoionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:724-728. [PMID: 28120300 DOI: 10.1007/s13361-016-1581-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/28/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
Solvent and ion source pressure were two important factors relating to the photon induced ion-molecule reactions in low pressure photoionization (LPPI). In this work, four anabolic steroids were analyzed by LPPI mass spectrometry. Both the ion species present and their relative abundances could be controlled by switching the solvent and adjusting the ion source pressure. Whereas M•+, MH+, [M - H2O]+, and solvent adducts were observed in positive LPPI, [M - H]- and various oxidation products were abundant in negative LPPI. Changing the solvent greatly affected formation of the ion species in both positive and negative ion modes. The ion intensities of the solvent adduct and oxygen adduct were selectively enhanced when the ion source pressure was elevated from 68 to 800 Pa. The limit of detection could be decreased by increasing the ion source pressure. Graphical Abstract ᅟ.
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Affiliation(s)
- Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Yanan Zhu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Wan Zhao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Deen Lu
- Department of Chemistry, University of California Davis, Davis, CA, 95616, USA
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China.
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16
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Shu J, Zou Y, Xu C, Li Z, Sun W, Yang B, Zhang H, Zhang P, Ma P. Protonation enhancement by dichloromethane doping in low-pressure photoionization. Sci Rep 2016; 6:36820. [PMID: 27905552 PMCID: PMC5131348 DOI: 10.1038/srep36820] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/21/2016] [Indexed: 02/07/2023] Open
Abstract
Doping has been used to enhance the ionization efficiency of analytes in atmospheric pressure photoionization, which is based on charge exchange. Compounds with excellent ionization efficiencies are usually chosen as dopants. In this paper, we report a new phenomenon observed in low-pressure photoionization: Protonation enhancement by dichloromethane (CH2Cl2) doping. CH2Cl2 is not a common dopant due to its high ionization energy (11.33 eV). The low-pressure photoionization source was built using a krypton VUV lamp that emits photons with energies of 10.0 and 10.6 eV and was operated at ~500-1000 Pa. Protonation of water, methanol, ethanol, and acetaldehyde was respectively enhanced by 481.7 ± 122.4, 197.8 ± 18.8, 87.3 ± 7.8, and 93.5 ± 35.5 times after doping 291 ppmv CH2Cl2, meanwhile CH2Cl2 almost does not generate noticeable ions itself. This phenomenon has not been documented in the literature. A new protonation process involving in ion-pair and H-bond formations was proposed to expound the phenomenon. The observed phenomenon opens a new prospect for the improvement of the detection efficiency of VUV photoionization.
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Affiliation(s)
- 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
- Shanghai Masteck Environment Co., Ltd, Shanghai, China
| | - Yao Zou
- 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
| | - 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
| | - Wanqi Sun
- 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
| | - Bo Yang
- 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
| | - Haixu Zhang
- 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
| | - Peng Zhang
- 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
| | - Pengkun Ma
- 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
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17
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Akutsu M, Sugie KI, Saito K. Analysis of 62 synthetic cannabinoids by gas chromatography-mass spectrometry with photoionization. Forensic Toxicol 2016; 35:94-103. [PMID: 28127409 PMCID: PMC5214763 DOI: 10.1007/s11419-016-0342-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 09/24/2016] [Indexed: 12/15/2022]
Abstract
Gas chromatography–mass spectrometry (GC–MS) in electron ionization (EI) mode is one of the most commonly used techniques for analysis of synthetic cannabinoids, because the GC–EI-MS spectra contain characteristic fragment ions for identification of a compound; however, the information on its molecular ions is frequently lacking. To obtain such molecular ion information, GC–MS in chemical ionization (CI) mode is frequently used. However, GC–CI-MS requires a relatively tedious process using reagent gas such as methane or isobutane. In this study, we show that GC–MS in photoionization (PI) mode provided molecular ions in all spectra of 62 synthetic cannabinoids, and 35 of the 62 compounds showed only the molecular radical cations. Except for the 35 compounds, the PI spectra showed very simple patterns with the molecular peak plus only a few fragment peak(s). An advantage is that the ion source for GC–PI-MS can easily be used for GC–EI-MS as well. Therefore, GC–EI/PI-MS will be a useful tool for the identification of synthetic cannabinoids contained in a dubious product. To the best of our knowledge, this is the first report to use GC–PI-MS for analysis of synthetic cannabinoids.
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Affiliation(s)
- Mamoru Akutsu
- Narcotics Control Department, Kanto-Shin'etsu Regional Bureau of Health and Welfare, Ministry of Health, Labour and Welfare, 1-2-1 Kudan-Minami, Chiyoda-ku, Tokyo, 102-8309 Japan
| | - Ken-Ichi Sugie
- Narcotics Control Department, Kanto-Shin'etsu Regional Bureau of Health and Welfare, Ministry of Health, Labour and Welfare, 1-2-1 Kudan-Minami, Chiyoda-ku, Tokyo, 102-8309 Japan
| | - Koichi Saito
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 4-41 Ebara 2-chome, Shinagawa-ku, Tokyo, 142-8501 Japan
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Liu C, Yang J, Wang J, Hu Y, Zhao W, Zhou Z, Qi F, Pan Y. Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1597-1605. [PMID: 27460208 DOI: 10.1007/s13361-016-1445-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 06/30/2016] [Accepted: 07/02/2016] [Indexed: 06/06/2023]
Abstract
Extractive atmospheric pressure photoionization (EAPPI) mass spectrometry was designed for rapid qualitative and quantitative analysis of chemicals in complex matrices. In this method, an ultrasonic nebulization system was applied to sample extraction, nebulization, and vaporization. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion-molecule reactions, and were mass-analyzed by a high resolution time-of-flight mass spectrometer (TOF-MS). After careful optimization and testing with pure sample solution, EAPPI was successfully applied to the fast screening of capsules, soil, natural products, and viscous compounds. Analysis was completed within a few seconds without the need for preseparation. Moreover, the quantification capability of EAPPI for matrices was evaluated by analyzing six polycyclic aromatic hydrocarbons (PAHs) in soil. The correlation coefficients (R (2) ) for standard curves of all six PAHs were above 0.99, and the detection limits were in the range of 0.16-0.34 ng/mg. In addition, EAPPI could also be used to monitor organic chemical reactions in real time. Graphical Abstract ᅟ.
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Affiliation(s)
- Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China
| | - Jian Wang
- Research and Development Centre, China Tobacco Anhui Industrial Co., Ltd., Hefei, 230088, China
| | - Yonghua Hu
- Research and Development Centre, China Tobacco Anhui Industrial Co., Ltd., Hefei, 230088, China
| | - Wan Zhao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China
| | - Zhongyue Zhou
- Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Fei Qi
- Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China.
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19
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Sun W, Liang M, Li Z, Shu J, Yang B, Xu C, Zou Y. Ultrasensitive detection of explosives and chemical warfare agents by low-pressure photoionization mass spectrometry. Talanta 2016; 156-157:191-195. [DOI: 10.1016/j.talanta.2016.05.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/03/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
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