<i>Ab initio</i> calculation of relative ion concentrations of protonated water clusters at equilibrium

Lee, E.P.F.; Dyke, John M.; Wilders, A.; Watts, Peter

doi:10.1080/00268979000101751

Cited by 17 publications

(5 citation statements)

References 27 publications

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“…The approach used for this calculation is described in more detail in previous publications. − Although this procedure only permits rough approximation due to the variety of data available and numerous determination methods used, the general trend of enhanced clustering with increasing humidity can be clearly identified. The results for the percentage distribution are summarized in Figure A for negative reactant ions and for product ions formed via dissociative electron attachment of halogenated compounds (shown in Figure B-D).…”

Section: Resultsmentioning

confidence: 99%

Accuracy of Ion Mobility Measurements Dependent on the Influence of Humidity

Mayer

Borsdorf

2014

Anal. Chem.

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Measurements with sensor techniques in field analytical chemistry can be considerably affected by varying ambient conditions such as humidity. We systematically investigated the way in which ion mobility measurements are influenced by moisture. Both the peak positions of product ions within the spectrum and their relative abundance can vary depending on humidity. The transportation of humidity via the carrier gas into the ion mobility spectrometer causes changes in ionization pathways. Additional reactant ion species are formed and a lower relative abundance of product ions from halogenated compounds was generally observed. The peak position within the ion mobility spectrum is comparatively unaffected for the same ions. In contrast, considerable differences in drift times detected were found with increasing humidity of drift gas, while the influence on calibration was not as significant for chlorinated and brominated substances as observed for humid carrier gases.

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Section: Resultsmentioning

confidence: 99%

Accuracy of Ion Mobility Measurements Dependent on the Influence of Humidity

Mayer

Borsdorf

2014

Anal. Chem.

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“…Ab initio calculations of water clustering in the water concentration range 1-24 605 ppm have been reported to be in good agreement with observed ion intensities recorded in accompanying experiments. 13 However the observation of hydrated chloride, chloride and chlorine ions in the first peak is thought to be due to fragmentation in the interface region between the IMS and the mass spectrometer. Similar behaviour has been observed with ammonium and ammonia clusters in dimethyldinitrobutane studies undertaken previously.…”

Section: Mass Spectra Obtained From Chlorine Atmentioning

confidence: 99%

The response of a membrane inlet ion mobility spectrometer to chlorine and the effect of water contamination of the drying media on ion mobility spectrometric responses to chlorine

Bocoş-Binţinţan

Brittain²,

Thomas³

2001

Analyst

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“…The n ‐distribution can be determined using standard thermodynamic and statistical‐mechanical methods. The Gibbs free energy changes and the gas‐phase equilibrium constants for reactions (1) at a temperature T can be evaluated from the standard thermodynamic relationships 22,23 :

normalΔ G_{T}^{0} = normalΔ H^{0} - T normalΔ S^{0}

K_{T} = \exp ()(, \frac{- Δ G_{T}^{0}}{italicRT})

…”

Section: Methodsmentioning

confidence: 99%

Reagent and analyte ion hydrates in secondary electrospray ionization mass spectrometry (SESI‐MS), their equilibrium distributions and dehydration in an ion transfer capillary: Modelling and experiments

Dryahina

Som

Smith

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale Secondary electrospray ionization (SESI) in a water spray environment at atmospheric pressure involves the reactions of hydrated hydronium reagent ions, H3O+(H2O)n, with trace analyte compounds in air samples. Understanding the formation and dehydration of reagent and analyte ions is the foundation for meaningful quantification of trace compounds by SESI‐mass spectrometry (MS). Methods A numerical model based on gas‐phase ion thermochemistry is developed that describes equilibria in H3O+(H2O)n reagent cluster ion distributions and ligand switching reactions with polar NH3 molecules leading to equilibrated hydrated ammonium ions NH4+(H2O)m. The model predictions are compared with experimental results obtained using a cylindrical SESI source coupled to an ion‐trap mass spectrometer via a heated ion transfer capillary. Non‐polar isoprene, C5H8, was used to further probe the nature of the reagent ions. Results Equilibrium distributions of H3O+(H2O)n ions and their reactions with NH3 molecules have been characterized by the model in the near‐atmospheric pressure SESI source. NH3 analyte molecules displace H2O ligands from the H3O+(H2O)n ions at the collisional rate forming NH4+(H2O)m ions, which travel through the heated ion transfer capillary losing H2O molecules. The data for variable NH3 concentrations match the model predictions and the C5H8 test substantiates the notion of dehydration in the heated capillary. Conclusions Large cluster ions formed in the SESI region are dehydrated to H3O+(H2O)1,2,3 and NH4+(H2O)1,2 while passing through the heated capillary, and considerable diffusion losses also occur. This phenomenon is also predicted for other polar analyte molecules, A, that can undergo similar switching reactions, thus forming AH+ and AH+(H2O)m analyte ions.

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Ab initio calculation of relative ion concentrations of protonated water clusters at equilibrium

Cited by 17 publications

References 27 publications

Accuracy of Ion Mobility Measurements Dependent on the Influence of Humidity

Accuracy of Ion Mobility Measurements Dependent on the Influence of Humidity

The response of a membrane inlet ion mobility spectrometer to chlorine and the effect of water contamination of the drying media on ion mobility spectrometric responses to chlorine

Reagent and analyte ion hydrates in secondary electrospray ionization mass spectrometry (SESI‐MS), their equilibrium distributions and dehydration in an ion transfer capillary: Modelling and experiments

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