Analysis of volatile short-chain fatty acids in the gas phase using secondary electrospray ionization coupled to mass spectrometry

Wüthrich, Cedric; Fan, Zhiyuan; Vergères, Guy; Wahl, Fabian; Zenobi, Renato; Giannoukos, Stamatios

doi:10.1039/d2ay01778d

Cited by 5 publications

(13 citation statements)

References 24 publications

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“…The data presented here indicate that ion suppression is less significant under humid conditions; i.e., humidifying the carrier gas flow can be a viable approach for decreasing ion suppression by approximately 30% (Figure ). However, it is essential to note that humidification may reduce the sensitivity for specific compound classes . Therefore, understanding how the humidity level of the carrier gas affects the analysis performance is crucial.…”

Section: Resultsmentioning

confidence: 99%

“…A slight drop in signal intensity was visible from the start (10 –2 ppm). These observations correspond to the general signal decrease from dry to humid conditions for the same gas-phase concentration previously observed for short-chain fatty acids . A more intense analyte signal was detected under dry conditions when compared with humid conditions with the same stock solution and evaporation chamber settings.…”

Section: Resultsmentioning

confidence: 99%

“…The mixing chamber outlet was connected to a commercial SESI source, which was attached to a Q Exactive Plus Orbitrap mass spectrometer. Reprinted in part with permission from ref . Copyright 2018 Elsevier, CC-By NC 3.0.…”

Section: Methodsmentioning

confidence: 99%

“…A previously described system that is based on evaporation chambers generated the individual gas standards . The principle of this system relies on Henry’s law, which describes the equilibrium between a gas and a solution at a known concentration.…”

Section: Methodsmentioning

confidence: 99%

“…Given the lack of thorough investigations into ion suppression in SESI, particularly in online breath measurements, these effects were investigated in detail. In this study, a gas generation system was used to examine the effect of variable compound concentrations on signal intensities. Acetone is of particular interest due to its high concentration in exhaled breath and its detection in positive ion mode, which is commonly used in clinical applications.…”

Section: Introductionmentioning

confidence: 99%

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Elucidating the Role of Ion Suppression in Secondary Electrospray Ionization

Wüthrich,

Giannoukos,

Zenobi

2023

J. Am. Soc. Mass Spectrom.

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Ion suppression is a known matrix effect in electrospray ionization (ESI), ambient pressure chemical ionization (APCI), and desorption electrospray ionization (DESI), but its characterization in secondary electrospray ionization (SESI) is lacking. A thorough understanding of this effect is crucial for quantitative applications of SESI, such as breath analysis. In this study, gas standards were generated by using an evaporation-based system to assess the susceptibility and suppression potential of acetone, deuterated acetone, deuterated acetic acid, and pyridine. Gas-phase effects were found to dominate ion suppression, with pyridine exhibiting the most significant suppressive effect, which is potentially linked to its gas-phase basicity. The impact of increased acetone levels on the volatiles from exhaled breath condensate was also examined. In humid conditions, a noticeable decrease in intensity of approximately 30% was observed for several features at an acetone concentration of 1 ppm. Considering that this concentration is expected for breath analysis, it becomes crucial to account for this effect when SESI is utilized to quantitatively determine specific compounds.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elucidating the Role of Ion Suppression in Secondary Electrospray Ionization

Wüthrich,

Giannoukos,

Zenobi

2023

J. Am. Soc. Mass Spectrom.

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Alternative electrolyte solutions for untargeted breath metabolomics using secondary‐electrospray ionization high‐resolution mass spectrometry

Wüthrich,

Zenobi,

Giannoukos

2024

Rapid Comm Mass Spectrometry

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RationaleSecondary‐electrospray ionization (SESI) coupled with high‐resolution mass spectrometry is a powerful tool for the discovery of biomarkers in exhaled breath. A primary electrospray consisting of aqueous formic acid (FA) is currently used to charge the volatile organic compounds in breath. To investigate whether alternate electrospray compositions could enable different metabolite coverage and sensitivities, the electrospray dopants NaI and AgNO3 were tested.MethodsIn a proof‐of‐principle manner, the exhaled breath of one subject was analyzed repeatedly with different electrospray solutions and with the help of a spectral stitching technique. Capillary diameter and position were optimized to achieve proper detection of exhaled breath. The detected features were then compared using formula annotation. Using an evaporation‐based gas standard system, the signal response of the different solutions was probed.ResultsPrincipal component analysis revealed a substantial difference in features detected with AgNO3. With silver, more sulfur‐containing features and more unsaturated hydrocarbon compounds were detected. Furthermore, more primary amines were potentially ionized, as indicated by van Krewelen diagrams. In total, twice as many features were unique to AgNO3 than for other electrospray dopants. Using gas standards at known concentrations, the high sensitivity of FA as a dopant was demonstrated but also indicated alternate sensitivities of the other electrospray solutions.ConclusionsThis work demonstrated the potential of AgNO3 as a complementary dopant for further biomarker discovery in SESI‐based breath analysis.

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Advances in secondary electrospray ionization for breath analysis and volatilomics

Wüthrich,

Giannoukos

2024

International Journal of Mass Spectrometry

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Analysis of volatile short-chain fatty acids in the gas phase using secondary electrospray ionization coupled to mass spectrometry

Abstract: Quantification of metabolites present within exhaled breath is a major challenge for on-line breath analysis. It is also important for gauging the analytical performance, accuracy, reproducibility, reliability, and stability of...

Cited by 5 publications

References 24 publications

Elucidating the Role of Ion Suppression in Secondary Electrospray Ionization

Elucidating the Role of Ion Suppression in Secondary Electrospray Ionization

Alternative electrolyte solutions for untargeted breath metabolomics using secondary‐electrospray ionization high‐resolution mass spectrometry

Advances in secondary electrospray ionization for breath analysis and volatilomics

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