Mechanistic study on the ionization of trace gases by an electrospray plume

Sinués, Pablo Martínez-Lozano; Criado, E.; Vidal, Guillermo

doi:10.1016/j.ijms.2011.12.010

Cited by 51 publications

(47 citation statements)

References 29 publications

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“…However, although the charging agent still remains unknown, the behavior shown in Figure 3 suggests that the mobility of the charging agent is similar to or slightly smaller than that of the lactic acid, so the charging agent might be a cluster comprising an OH -ion and a few molecules of water or methanol. This result is in agreement with recent studies by Martínez-Lozano [8], and also supports the original hypothesis that we cannot detect the charging agent simply because it is too small for our analyzer. Figure 4 shows the curves n s n Ã s $ n Ã b n tot = (sample ion concentration as a function of buffer vapor concentration) evaluated both theoretically and experimentally for different saturated fatty acids at concentrations near 1 ppb acting as sample species (where C1 here stands for the molecule having only one C atom, C2 for the fatty acid molecule having two C atoms, and so on) and lactic acid acting as buffer (at concentrations up to 30 ppb).…”

Section: Comparison Of Theoretical and Experimental Datasupporting

confidence: 93%

“…Most of them are lost in this journey, but we hypothesize that for the range in which we are interested, the fraction reaching the sensor is fixed (independent of m/z). In this respect, we know that the QStar XL mass analyzer gain is approximately constant through this mass range [8]. Because the gas is clean in the clean region (from the sample gas region to the MS inlet), ions are only affected by space charge repulsion, but this effect can be minimized as long as the electrostatic field is stronger than the Coulomb repulsion.…”

Section: Methodsmentioning

confidence: 99%

“…Whether vapor charging takes place directly via contact with the droplets, or indirectly by charge transfer from ions released from the droplets, remains unclear [7]. Recent studies [8] using a secondary electrospray ionization, differential mobility analyzing and mass spectrometry (SESI-DMA-MS) analyzer with a charging electrospray of formic acid, and vapors containing different types of amides, suggest that the ions option is more likely to be happening. In this case, the charge transmission reaction taking place would be: formiate -+amide → amide -+ formic.…”

Section: T He Ionization Of Vapors By Means Of Electrosprays Ormentioning

confidence: 99%

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Secondary Electrospray Ionization of Complex Vapor Mixtures. Theoretical and Experimental Approach

Vidal-de-Miguel

Herrero²

2012

J. Am. Soc. Mass Spectrom.

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In secondary electrospray ionization (SESI) systems, gaseous analytes exposed to an electrospray plume become ionized after charge is transferred from the charging electrosprayed particles (the charging agent) to the vapor species. Currently available SESI models are valid for simplified systems having only one type of electrosprayed species, which ionizes only one single vapor species, and for the limit of low vapor concentration. More realistic models require considering other effects. Here we develop a theoretical model that accounts for the effects of high vapor concentration, saturation effects, interferences between different vapor species, and electrosprays producing different types of species from the liquid phase. In spite of the relatively high complexity of the problem, we find simple relations between the different ionic species concentrations that hold independently of the particular ion source configuration. Our model suggests that an ideal SESI system should use highly concentrated charging agents composed preferably of only one dominating species with low mobility. Experimental measurements with a MeOH-H 2 O-NH 3 electrospray and a mixture of fatty acids and lactic acid served to test the theory, which gives good qualitative results. These results also suggest that the SESI ionization mechanism is primarily based on ions rather than on charged droplets.

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Section: Comparison Of Theoretical and Experimental Datasupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: T He Ionization Of Vapors By Means Of Electrosprays Ormentioning

confidence: 99%

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Secondary Electrospray Ionization of Complex Vapor Mixtures. Theoretical and Experimental Approach

Vidal-de-Miguel

Herrero²

2012

J. Am. Soc. Mass Spectrom.

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“…The experimental set-up was previously presented in detail [22,24,26,28,30,31,32,33,34,37]. Briefly, the entrance of a commercial quadrupole time-of-flight mass spectrometer (Ultima, Waters, Milford, Mass., USA) was slightly modified to allow for the admission of breath samples through a heated Teflon tube.…”

Section: Methodsmentioning

confidence: 99%

Breath Analysis in Real Time by Mass Spectrometry in Chronic Obstructive Pulmonary Disease

et al. 2014

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Background: It has been suggested that exhaled breath contains relevant information on health status. Objectives: We hypothesized that a novel mass spectrometry (MS) technique to analyze breath in real time could be useful to differentiate breathprints from chronic obstructive pulmonary disease (COPD) patients and controls (smokers and nonsmokers). Methods: We studied 61 participants including 25 COPD patients [Global Initiative for Obstructive Lung Disease (GOLD) stages I-IV], 25 nonsmoking controls and 11 smoking controls. We analyzed their breath by MS in real time. Raw mass spectra were then processed and statistically analyzed. Results: A panel of discriminating mass-spectral features was identified for COPD (all stages; n = 25) versus healthy nonsmokers (n = 25), COPD (all stages; n = 25) versus healthy smokers (n = 11) and mild COPD (GOLD stages I/II; n = 13) versus severe COPD (GOLD stages III/IV; n = 12). A blind classification (i.e. leave-one-out cross validation) resulted in 96% sensitivity and 72.7% specificity (COPD vs. smoking controls), 88% sensitivity and 92% specificity (COPD vs. nonsmoking controls) and 92.3% sensitivity and 83.3% specificity (GOLD I/II vs. GOLD III/IV). Acetone and indole were identified as two of the discriminating exhaled molecules. Conclusions: We conclude that real-time MS may be a useful technique to analyze and characterize the metabolome of exhaled breath. The acquisition of breathprints in a rapid manner may be valuable to support COPD diagnosis and to gain insight into the disease.

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“…Although the process is thought to be driven by gas-phase ion molecules reactions [29], which takes place at the sub-micrometer scale. As a result, the macroscopic description of the process can be decoupled from the actual charge exchange mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling and experimental validation of a universal secondary electrospray ionization source for mass spectrometric gas analysis in real-time

Barrios-Collado

Vidal-de-Miguel

Sinués

2016

Sensors and Actuators B: Chemical

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The process by which ambient vapors are ionized upon interaction with electrosprays is not fully understood, compromising its optimization and widespread use. In this work we evaluated the different scales associated with the processes involved in secondary electrospray ionization (SESI), and developed a new numerical method that merges the analytical solution that describes the angle of aperture and the current of an ideal electrospray, with a Finite Element Method that enables the evaluation of complex geometries. The numerical method showed that, despite the low ionization efficiency (i.e. ion concentration/neutral vapor concentration ~ 10 -4 ), depletion of neutral vapors plays an important role. We used this method to optimize and design a Low Flow SESI source, which was coupled with a commercial high resolution/high mass accuracy mass spectrometer. The system was designed to be interfaced with virtually any pre-existing atmospheric pressure ionization mass spectrometer. The experimental validation for the detection of ambient vapors confirmed qualitatively the numerical predictions in terms of ionization efficiency as a function of sample flow rate. As a result of the optimization, this prototype showed a 5 fold sensitivity increase against standard SESI.This novel add-on is meant to upgrade mass spectrometers to analyze trace gases in real time by SESI technique.

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Mechanistic study on the ionization of trace gases by an electrospray plume

Cited by 51 publications

References 29 publications

Secondary Electrospray Ionization of Complex Vapor Mixtures. Theoretical and Experimental Approach

Secondary Electrospray Ionization of Complex Vapor Mixtures. Theoretical and Experimental Approach

Breath Analysis in Real Time by Mass Spectrometry in Chronic Obstructive Pulmonary Disease

Numerical modeling and experimental validation of a universal secondary electrospray ionization source for mass spectrometric gas analysis in real-time

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