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Cuervo L, Méndez C, Olano C, Malmierca MG. Volatilome: Smells like microbial spirit. ADVANCES IN APPLIED MICROBIOLOGY 2024; 127:1-43. [PMID: 38763526 DOI: 10.1016/bs.aambs.2024.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
In recent years, the study of volatile compounds has sparked interest due to their implications in signaling and the enormous variety of bioactive properties attributed to them. Despite the absence of analysis methods standardization, there are a multitude of tools and databases that allow the identification and quantification of volatile compounds. These compounds are chemically heterogeneous and their diverse properties are exploited by various fields such as cosmetics, the food industry, agriculture and medicine, some of which will be discussed here. In virtue of volatile compounds being ubiquitous and fast chemical messengers, these molecules mediate a large number of interspecific and intraspecific interactions, which are key at an ecological level to maintaining the balance and correct functioning of ecosystems. This review briefly summarized the role of volatile compounds in inter- and intra-specific relationships as well as industrial applications associated with the use of these compounds that is emerging as a promising field of study.
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Affiliation(s)
- Lorena Cuervo
- Functional Biology Department, University of Oviedo, Oviedo, Spain; University Institute of Oncology of Asturias, University of Oviedo, Oviedo, Spain; Health Research Institute of Asturias, Av. del Hospital Universitario, s/n, Oviedo, Spain
| | - Carmen Méndez
- Functional Biology Department, University of Oviedo, Oviedo, Spain; University Institute of Oncology of Asturias, University of Oviedo, Oviedo, Spain; Health Research Institute of Asturias, Av. del Hospital Universitario, s/n, Oviedo, Spain
| | - Carlos Olano
- Functional Biology Department, University of Oviedo, Oviedo, Spain; University Institute of Oncology of Asturias, University of Oviedo, Oviedo, Spain; Health Research Institute of Asturias, Av. del Hospital Universitario, s/n, Oviedo, Spain
| | - Mónica G Malmierca
- Functional Biology Department, University of Oviedo, Oviedo, Spain; University Institute of Oncology of Asturias, University of Oviedo, Oviedo, Spain; Health Research Institute of Asturias, Av. del Hospital Universitario, s/n, Oviedo, Spain.
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Sola-Martínez RA, Zeng J, Awchi M, Gisler A, Arnold K, Singh KD, Frey U, Díaz MC, de Diego Puente T, Sinues P. Preservation of exhaled breath samples for analysis by off-line SESI-HRMS: proof-of-concept study. J Breath Res 2023; 18:011002. [PMID: 38029449 DOI: 10.1088/1752-7163/ad10e1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 11/29/2023] [Indexed: 12/01/2023]
Abstract
Secondary electrospray ionization-high resolution mass spectrometry (SESI-HRMS) is an established technique in the field of breath analysis characterized by its short analysis time, as well as high levels of sensitivity and selectivity. Traditionally, SESI-HRMS has been used for real-time breath analysis, which requires subjects to be at the location of the analytical platform. Therefore, it limits the possibilities for an introduction of this methodology in day-to-day clinical practice. However, recent methodological developments have shown feasibility on the remote sampling of exhaled breath in Nalophan® bags prior to measurement using SESI-HRMS. To further explore the range of applications of this method, we conducted a proof-of-concept study to assess the impact of the storage time of exhaled breath in Nalophan® bags at different temperatures (room temperature and dry ice) on the relative intensities of the compounds. In addition, we performed a detailed study of the storage effect of 27 aldehydes related to oxidative stress. After 2 h of storage, the mean of intensity of allm/zsignals relative to the samples analyzed without prior storage remained above 80% at both room temperature and dry ice. For the 27 aldehydes, the mean relative intensity losses were lower than 20% at 24 h of storage, remaining practically stable since the first hour of storage following sample collection. Furthermore, the mean relative intensity of most aldehydes in samples stored at room temperature was higher than those stored in dry ice, which could be related to water vapor condensation issues. These findings indicate that the exhaled breath samples could be preserved for hours with a low percentage of mean relative intensity loss, thereby allowing more flexibility in the logistics of off-line SESI-HRMS studies.
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Affiliation(s)
- Rosa A Sola-Martínez
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Murcia, Spain
| | - Jiafa Zeng
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Mo Awchi
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Amanda Gisler
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
| | - Kim Arnold
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Kapil Dev Singh
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Urs Frey
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Pediatric Respiratory Medicine, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Manuel Cánovas Díaz
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Murcia, Spain
| | - Teresa de Diego Puente
- Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Murcia, Spain
| | - Pablo Sinues
- University of Basel Children's Hospital (UKBB), Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
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Awchi M, Singh KD, Dill PE, Frey U, Datta AN, Sinues P. Prediction of systemic free and total valproic acid by off-line analysis of exhaled breath in epileptic children and adolescents. J Breath Res 2023; 17:046013. [PMID: 37678210 DOI: 10.1088/1752-7163/acf782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 09/07/2023] [Indexed: 09/09/2023]
Abstract
Therapeutic drug monitoring (TDM) of medications with a narrow therapeutic window is a common clinical practice to minimize toxic effects and maximize clinical outcomes. Routine analyses rely on the quantification of systemic blood concentrations of drugs. Alternative matrices such as exhaled breath are appealing because of their inherent non-invasive nature. This is especially the case for pediatric patients. We have recently showcased the possibility of predicting systemic concentrations of valproic acid (VPA), an anti-seizure medication by real-time breath analysis in two real clinical settings. This approach, however, comes with the limitation of the patients having to physically exhale into the mass spectrometer. This restricts the possibility of sampling from patients not capable or available to exhale into the mass spectrometer located on the hospital premises. In this work, we developed an alternative method to overcome this limitation by collecting the breath samples in customized bags and subsequently analyzing them by secondary electrospray ionization coupled to high-resolution mass spectrometry (SESI-HRMS). A total ofn= 40 patients (mean ± SD, 11.5 ± 3.5 y.o.) diagnosed with epilepsy and taking VPA were included in this study. The patients underwent three measurements: (i) serum concentrations of total and free VPA, (ii) real-time breath analysis and (iii) off-line analysis of exhaled breath collected in bags. The agreement between the real-time and the off-line breath analysis methods was evaluated using Lin's concordance correlation coefficient (CCC). CCC was computed for ten mass spectral predictors of VPA concentrations. Lin's CCC was >0.6 for all VPA-associated features, except for two low-signal intensity isotopic peaks. Finally, free and total serum VPA concentrations were predicted by cross validating the off-line data set. Support vector machine algorithms provided the most accurate predictions with a root mean square error of cross validation of 29.0 ± 7.4 mg l-1and 3.9 ± 1.4 mg l-1for total and free VPA (mean ± SD), respectively. As a secondary analysis, we explored whether exhaled metabolites previously associated with side-effects and response to medication could be rendered by the off-line analysis method. We found that five features associated with side effects showed a CCC > 0.6, whereas none of the drug response-associated peaks reached this cut-off. We conclude that the clinically relevant free fraction of VPA can be predicted by this combination of off-line breath collection with rapid SESI-HRMS analysis. This opens new possibilities for breath based TDM in clinical settings.
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Affiliation(s)
- Mo Awchi
- University Children's Hospital Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Kapil Dev Singh
- University Children's Hospital Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | | | - Urs Frey
- University Children's Hospital Basel, Basel, Switzerland
| | | | - Pablo Sinues
- University Children's Hospital Basel, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
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Španěl P, Dryahina K, Omezzine Gnioua M, Smith D. Different reactivities of H 3 O + (H 2 O) n with unsaturated and saturated aldehydes: ligand-switching reactions govern the quantitative analytical sensitivity of SESI-MS. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9496. [PMID: 36807598 DOI: 10.1002/rcm.9496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/15/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
RATIONALE The detection sensitivity of secondary electrospray ionisation mass spectrometry (SESI-MS) is much lower for saturated aldehydes than for unsaturated aldehydes. This needs to be understood in terms of gas phase ion-molecule reaction kinetics and energetics to make SESI-MS analytically more quantitative. METHODS Parallel SESI-MS and selected ion flow tube mass spectrometry (SIFT-MS) analyses were carried out of air containing variable accurately determined concentrations of saturated (C5, pentanal; C7, heptanal; C8 octanal) and unsaturated (C5, 2-pentenal; C7, 2-heptenal; C8, 2-octenal) aldehyde vapours. The influence of the source gas humidity and the ion transfer capillary temperature, 250 and 300°C, in a commercial SESI-MS instrument was explored. Separate experiments were carried out using SIFT to determine the rate coefficients, k73 , for the ligand-switching reactions of the H3 O+ (H2 O)3 ions with the six aldehydes. RESULTS The relative slopes of the plots of SESI-MS ion signal against SIFT-MS concentration were interpreted as the relative SESI-MS sensitivities for these six compounds. The sensitivities for the unsaturated aldehydes were 20 to 60 times greater than for the corresponding C5, C7 and C8 saturated aldehydes. Additionally, the SIFT experiments revealed that the measured k73 are three or four times greater for the unsaturated than for the saturated aldehydes. CONCLUSIONS The trends in SESI-MS sensitivities are rationally explained by differences in the rates of the ligand-switching reactions, which are justified by theoretically calculated equilibrium rate constants derived from thermochemical density functional theory (DFT) calculations of Gibb's free energy changes. The humidity of SESI gas thus favours the reverse reactions of the saturated aldehyde analyte ions, effectively suppressing their signals in contrast to their unsaturated counterparts.
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Affiliation(s)
- Patrik Španěl
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Kseniya Dryahina
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Maroua Omezzine Gnioua
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - David Smith
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
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Ghosh D, Basak M, Deka D, Das G. Quinoxaline-probe embedded injectable fluorogenic hydrogels: Comparative detection of mesitylene in guar gum and i-carrageenan hydrogels. Int J Biol Macromol 2023; 229:615-623. [PMID: 36592851 DOI: 10.1016/j.ijbiomac.2022.12.310] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/01/2023]
Abstract
The innovation of novel chemosensor probes for the recognition of trace volatile organic compounds is critical due to their hazardous effect on the environment and human health. A nitro-group integrated quinoxaline probe with a profound discriminative fluorescence 'turn-on' response to mesitylene was fabricated into guar gum and i-carrageenan, two biopolymer-based hydrogel matrices, to develop compact, portable fluorogenic hydrogel sensors and assess their fluorescence properties. A comparative characterization-based analysis of native, probe-associated, and probe-analyte-associated hydrogels, (comprising of FT-IR, XRD, TGA) was investigated to ascertain the overall compatibility of the hydrogel-based sensors for use as a smart rapid detection tool. Dynamic rheological measurements also validated the mechanical stability and robustness of the developed hydrogel matrices. Fluorescence spectroscopic investigations yielded promising results of 0.15 ppm limit of detection (LOD) in guar gum and 0.29 ppm LOD in i-carrageenan hydrogels respectively. FESEM and Fluorescence microscopy studies represented the morphological variations of the hydrogel sensors on interaction with mesitylene. The practical feasibility of the chemosensor in hydrogel form for mesitylene detection in the vapor phase was also explored. Probe-embedded hydrogels with injectable property was shown, depicting its use as security ink for information encryption functions. This approach of incorporating chemosensors into biobased hydrogel networks has the potential to broaden its opportunities in the field of chemical, biomedical, and environmental sensing sectors.
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Affiliation(s)
- Debolina Ghosh
- Centre for the Environment, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Megha Basak
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Deepmoni Deka
- Centre for the Environment, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Gopal Das
- Centre for the Environment, Indian Institute of Technology Guwahati, Assam 781039, India; Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India.
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Zhao Y, Chen D, Duan H, Li P, Wu W, Wang X, Poapolathep A, Poapolathep S, Logrieco AF, Pascale M, Wang C, Zhang Z. Sample preparation and mass spectrometry for determining mycotoxins, hazardous fungi, and their metabolites in the environment, food, and healthcare. Trends Analyt Chem 2023. [DOI: 10.1016/j.trac.2023.116962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Streckenbach B, Sakas J, Perkins N, Kohler M, Moeller A, Zenobi R. A gas-phase standard delivery system for direct breath analysis. J Breath Res 2022; 17. [PMID: 36579824 DOI: 10.1088/1752-7163/acab79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/14/2022] [Indexed: 12/15/2022]
Abstract
Applications for direct breath analysis by mass spectrometry (MS) are rapidly expanding. One of the more recent mass spectrometry-based approaches is secondary electrospray ionization coupled to high-resolution mass spectrometry (SESI-HRMS). Despite increasing usage, the SESI methodology still lacks standardization procedures for quality control and absolute quantification. In this study, we designed and evaluated a custom-built standard delivery system tailored for direct breath analysis. The system enables the simultaneous introduction of multiple gas-phase standard compounds into ambient MS setups in the lower parts-per-million (ppm) to parts-per-billion (ppb) range. To best mimic exhaled breath, the gas flow can be heated (37 °C-40 °C) and humidified (up to 98% relative humidity). Inter-laboratory comparison of the system included various SESI-HRMS setups, i.e. an Orbitrap and a quadrupole time-of-flight mass spectrometer (QTOF), and using both single- as well as multi-component standards. This revealed highly stable and reproducible performances with between-run variation <19% and within-run variation <20%. Independent calibration runs demonstrated high accuracy (96%-111%) and precision (>95%) for the single-compound standard acetone, while compound-specific performances were obtained for the multi-component standard. Similarly, the sensitivity varied for different compounds within the multi-component standard across all SESI-Orbitrap and -QTOF setups, yielding limits of detections from 3.1 ppb (forp-xylene) to 0.05 ppb (for 1,8-cineol). Routinely applying the standard system throughout several weeks, allowed us to monitor instrument stability and to identify technical outliers in exhaled breath measurements. Such routine deployment of standards would significantly improve data quality and comparability, which is especially important in longitudinal and multi-center studies. Furthermore, performance validation of the system demonstrated its suitability for reliable absolute quantification while it illustrated compound-dependent behavior for SESI.
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Affiliation(s)
- Bettina Streckenbach
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Justinas Sakas
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.,EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, United Kingdom
| | - Nathan Perkins
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, Switzerland
| | - Malcolm Kohler
- Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland
| | - Alexander Moeller
- Division of Respiratory Medicine, University Children's Hospital Zurich, Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
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Xu X, Pang H, Liu C, Wang K, Loisel G, Li L, Gligorovski S, Li X. Real-time measurements of product compounds formed through the reaction of ozone with breath exhaled VOCs. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:2237-2248. [PMID: 36472140 DOI: 10.1039/d2em00339b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Human presence can affect indoor air quality because of secondary organic compounds formed upon reactions between gaseous oxidant species, e.g., ozone (O3), hydroxyl radicals (OH), and chemical compounds from skin, exhaled breath, hair and clothes. We assess the gas-phase product compounds generated by reactions of gaseous O3 with volatile organic compounds (VOCs) from exhaled human breath by real time analysis using a high-resolution quadrupole-orbitrap mass spectrometer (HRMS) coupled to a secondary electrospray ionization (SESI) source. Based on the product compounds identified we propose a reaction mechanism initiated by O3 oxidation of the most common breath constituents, isoprene, α-terpinene and ammonia (NH3). The reaction of O3 with isoprene and α-terpinene generates ketones and aldehydes such as 3,4-dihydroxy-2-butanone, methyl vinyl ketone, 3-carbonyl butyraldehyde, formaldehyde and toxic compounds such as 3-methyl furan. Formation of compounds with reduced nitrogen containing functional groups such as amines, imines and imides is highly plausible through NH3 initiated cleavage of the C-O bond. The detected gas-phase product compounds suggest that human breath can additionally affect indoor air quality through the formation of harmful secondary products and future epidemiological studies should evaluate the potential health effects of these compounds.
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Affiliation(s)
- Xin Xu
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China.
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China
| | - Hongwei Pang
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Chao Liu
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China.
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China
| | - Kangyi Wang
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China.
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China
| | - Gwendal Loisel
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Lei Li
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China.
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China
| | - Sasho Gligorovski
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Xue Li
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China.
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 510632, China
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Kaeslin J, Wüthrich C, Giannoukos S, Zenobi R. How Soft Is Secondary Electrospray Ionization? JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1967-1974. [PMID: 36111835 DOI: 10.1021/jasms.2c00201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Secondary electrospray ionization (SESI) mass spectrometry (MS) is a direct infusion technique often used for untargeted metabolomics, e.g., for online breath analysis. SESI is thought to be a soft ionization method, which is important to avoid interference from in-source fragments and to simplify compound annotation. In this work, benzylammonium ions, formed from volatile benzylamines, with known bond dissociation enthalpies were used as thermometer ions to investigate the internal energy distribution of ions that are produced by SESI. It is shown that SESI is softer than electrospray ionization (ESI), and therefore, SESI indeed qualifies as a soft ionization technique. However, we also found that the standard MS instrument settings used in the SESI community are relatively harsh. Proper soft tuning of the instrument is essential to fully benefit from the softness that SESI can provide. Moreover, there is evidence from in-source collision-induced dissociation (CID) experiments that analytes can be solvated in SESI under soft conditions, which supports a recently proposed SESI mechanism referred to as ligand switching.
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Affiliation(s)
- Jérôme Kaeslin
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Cedric Wüthrich
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Stamatios Giannoukos
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
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Yu Q, Gao J, Yu X, Shi J, Lin L, Wang X. Implementing reactive secondary electrospray ionization based on gas–droplet reactions for VOC analysis. Analyst 2022; 147:4903-4909. [DOI: 10.1039/d2an01422j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A reactive secondary electrospray ionization method is proposed based on accelerated gas–liquid reactions in microdroplets. It enables online derivatization of volatile organic compounds and can facilitate rapid analysis of these samples.
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Affiliation(s)
- Quan Yu
- Division of Advanced Manufacturing, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Jing Gao
- Division of Advanced Manufacturing, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Xiaohua Yu
- Open FIESTA, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Jianbo Shi
- Open FIESTA, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Lin Lin
- Sustech Core Research Facilities, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiaohao Wang
- Division of Advanced Manufacturing, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
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Dryahina K, Polášek M, Smith D, Španěl P. Sensitivity of secondary electrospray ionization mass spectrometry to a range of volatile organic compounds: Ligand switching ion chemistry and the influence of Zspray™ guiding electric fields. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9187. [PMID: 34473872 DOI: 10.1002/rcm.9187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Secondary electrospray ionization (SESI) is currently only semi-quantitative. In the Zspray™ arrangement of SESI-MS, the transfer of ions from near atmospheric pressure to a triple quadrupole is achieved by guiding electric fields that partially desolvate both reagent and analyte ions which must be understood. Also, to make SESI-MS more quantitative, the mechanisms and the kinetics of the reaction processes, especially ligand switching reactions of hydrated hydronium reagent ions, H3 O+ (H2 O)n , with volatile organic compound (VOC) molecules, need to be understood. METHODS A modified Zspray™ ESI ion source operating at sub-atmospheric pressure with analyte sample gas introduced via an inlet coaxial with the spray was used. Variation of the ion-guiding electric fields was used to reveal the degree of desolvation of both reagent and analyte ions. The instrument sensitivity was determined for several classes of VOCs by introducing bag samples of suitably varying concentrations as quantified on-line using selected ion flow tube MS. RESULTS Electric field desolvation resulted in largely protonated VOCs, MH+ , and their monohydrates, MH+ H2 O, and for some VOCs proton-bound dimer ions, MH+ M, were formed. There was a highly linear response of the ion signal to the measured VOC sample concentration, which provided the instrument sensitivities, S, for 25 VOCs. The startling results show very wide variations in S from near 0 to 1 for hydrocarbons, and up to 100, on a relative scale, for polar compounds such as monoketones and unsaturated aldehydes. CONCLUSIONS The complex ion chemistry occurring in the SESI ion source, largely involving gas-phase ligand switching, results in widely variable sensitivities for different classes of VOCs. The sensitivity is observed to depend on the dipole moment and proton affinity of the analyte VOC molecule, M, and to decrease with the observed fraction of MH+ H2 O, but other yet unrecognized factors must play a significant role.
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Affiliation(s)
- Kseniya Dryahina
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Miroslav Polášek
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - David Smith
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Patrik Španěl
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
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