Selective reagent ion-time of flight-mass spectrometry study of six common monoterpenes

Materić, Dušan; Lanza, Matteo; Sulzer, Philipp; Herbig, Jens; Bruhn, Dan; Gauci, Vincent; Mason, Nigel J.; Turner, Claire

doi:10.1016/j.ijms.2017.06.003

Cited by 15 publications

(17 citation statements)

References 22 publications

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“…Here we record only ion signals, which are detected with relative intensities >1%. Other fragments reported in the literature for H 3 O + chemical ionization using PTR-MS instruments (Wang et al, 2003; Schoon et al, 2004; Tani et al, 2004; Materić et al, 2017) have not been observed. This could be explained by the smaller amount of transferred internal energy using NH4+ instead of H 3 O + as reagent ion.…”

Section: Resultsmentioning

confidence: 88%

NH4+ Association and Proton Transfer Reactions With a Series of Organic Molecules

et al. 2019

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In this study, we present reactions of with a series of analytes (A): acetone (C 3 H 6 O), methyl vinyl ketone (C 4 H 6 O), methyl ethyl ketone (C 4 H 8 O), and eight monoterpene isomers (C 10 H 16 ) using a Selective Reagent Ionization Time-of-Flight Mass Spectrometer (SRI-ToF-MS). We studied the ion-molecule reactions at collision energies of 55 and 80 meV. The ketones, having a substantially lower proton affinity than NH 3 , produce only cluster ions (A) in detectable amounts at 55 meV. At 80 meV, no cluster ions were detected meaning that these adduct ions are formed by strongly temperature dependent association reactions. Bond energies of cluster ions and proton affinities for most monoterpenes are not known and were estimated by high level quantum chemical calculations. The calculations reveal monoterpene proton affinities, which range from slightly smaller to substantially higher than the proton affinity of NH 3 . Proton affinities and cluster bond energies allow to group the monoterpenes as a function of the enthalpy for the dissociation reaction . We find that this enthalpy can be used to predict the (A) cluster ion yield. The present study explains product ion formation involving ion chemistry. This is of importance for chemical ionization mass spectrometry (CIMS) utilizing as well as (H 2 O) as reagent ions to quantitatively detect atmospherically important organic compounds in real-time.

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Section: Resultsmentioning

confidence: 88%

NH4+ Association and Proton Transfer Reactions With a Series of Organic Molecules

et al. 2019

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“…This can be achieved by (i) changing the reagent ion, examples for which have been presented in the literature for explosives (Sulzer et al, 2013; Agarwal et al, 2014), or psychoactive substances (Acton et al, 2014; Lanza et al, 2015), and/or (ii) the collisional processes in the drift tube through changing the reduced electric field. Changes in the reduced electric field (the ratio of the electric field strength, E , to the gas number density, N , in the drift tube) to alter the product ion distributions have been demonstrated in the areas of homeland security, e.g., detection of chemical warfare agents (Petersson et al, 2009), explosives (Mayhew et al, 2010; Sulzer et al, 2012, 2013), and rape drugs (Jürschik et al, 2012), and in environmental science, e.g., the identification of monoterpenes (Materić et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Compendium of the Reactions of H3O+ With Selected Ketones of Relevance to Breath Analysis Using Proton Transfer Reaction Mass Spectrometry

et al. 2019

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Soft chemical ionization mass spectrometric techniques, such as proton transfer reaction mass spectrometry (PTR-MS), are often used in breath analysis, being particularly powerful for real-time measurements. To ascertain the type and concentration of volatiles in exhaled breath clearly assignable product ions resulting from these volatiles need to be determined. This is difficult for compounds where isomers are common, and one important class of breath volatiles where this occurs are ketones. Here we present a series of extensive measurements on the reactions of H 3 O + with a selection of ketones using PTR-MS. Of particular interest is to determine if ketone isomers can be distinguished without the need for pre-separation by manipulating the ion chemistry through changes in the reduced electric field. An additional issue for breath analysis is that the product ion distributions for these breath volatiles are usually determined from direct PTR-MS measurements of the compounds under the normal operating conditions of the instruments. Generally, no account is made for the effects on the ion-molecule reactions by the introduction of humid air samples or increased CO 2 concentrations into the drift tubes of these analytical devices resulting from breath. Therefore, another motivation of this study is to determine the effects, if any, on the product ion distributions under the humid conditions associated with breath sampling. However, the ultimate objective for this study is to provide a valuable database of use to other researchers in the field of breath analysis to aid in analysis and quantification of trace amounts of ketones in human breath. Here we present a comprehensive compendium of the product ion distributions as a function of the reduced electric field for the reactions of H 3 O + . (H 2 O) n ( n = 0 and 1) with nineteen ketones under normal and humid (100% relative humidity for 37 °C) PTR-MS conditions. The ketones selected for inclusion in this compendium are (in order of increasing molecular weight): 2-butanone; 2-pentanone; 3-pentanone; 2-hexanone; 3-hexanone; 2-heptanone; 3-heptanone; 4-heptanone; 3-octanone; 2-nonanone; 3-nonanone; 2-decanone; 3-decanone; cyclohexanone; 3-methyl-2-butanone; 3-methyl-2-pentanone; 2-methyl-3-pentanone; 2-methyl-3-hexanone; and 2-methyl-3-heptanone.

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“…It is well known that NO + reacts with monoterpenes via charge transfer and in most cases the molecular cation C 10 H 16 +• at m/z 136 is the dominant product ion. [9][10][11] Thus it is necessary to account for about 25% of NO + present in the DTR to obtain the correct data for product ion distribution for reaction with C 8 H 8 +• (and possibly (C 8 H 8 ) 2 +• ). Fortunately, it is easy to do this from the ion-molecule reaction kinetics when the reaction rate coefficient k and the reaction time t r are known.…”

Section: Correction Due To Presence Of No +mentioning

confidence: 99%

“…Measurements of the total concentration of monoterpenes in air can be achieved by chemical ionization mass spectrometry, CIMS, techniques based on ion‐molecule reactions in flow/drift tube reactors, where ionization of the neutral monoterpene molecules is usually accomplished by gas‐phase reactions with H 3 O + or NO + reagent ions taking place at air sample pressures <2 mbar as realized in proton transfer reaction mass spectrometry, PTR‐MS, and selected ion flow tube mass spectrometry, SIFT‐MS . This allows real‐time quantification of atmospheric monoterpenes at concentration levels down to 1 part per billion per volume, ppbv, and lower.…”

Section: Introductionmentioning

confidence: 99%

Styrene radical cations for chemical ionization mass spectrometry analyses of monoterpene hydrocarbons

Spesyvyi

Španěl

Sovová

2019

Rapid Comm Mass Spectrometry

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Rationale Monoterpene hydrocarbons play an important role in the formation of secondary aerosol particles and in atmospheric chemistry. Thus, there is a demand to measure their individual concentrations in situ in real time. Currently, only the total concentration of monoterpenes C10H16 can be determined by chemical ionization mass spectrometry techniques using reagent ions H3O+, NO+ and (C6H6)n+• without gas chromatographic separation. Methods The styrene cation C8H8+• was investigated as a reagent for chemical ionization of monoterpenes. The modified selected ion flow drift tube, SIFDT, technique was used to characterize the differences in product ion distributions between α‐phellandrene, α‐pinene, γ‐terpinene, β‐pinene, ocimene, sabinene, 3‐carene, (R)‐limonene, camphene and myrcene. Results The monoterpene molecular cation C10H16+• is the main product (about 90%) for all isomers except (R)‐limonene and camphene with an efficient channel of C8H8+•C10H16 adduct formation and γ‐terpinene with unexpectedly significant product ions at m/z 134 and 135 corresponding to losses of H2 and H. Conclusions Utilization of the styrene cation for the ionization of monoterpenes is beneficial due to the very low fragmentation of the product ions. Specific association product ions for camphene and (R)‐limonene and fragment product ions for γ‐terpinene allow them to be distinguished from other isomers that produce mostly the molecular cation.

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Selective reagent ion-time of flight-mass spectrometry study of six common monoterpenes

Cited by 15 publications

References 22 publications

NH4+ Association and Proton Transfer Reactions With a Series of Organic Molecules

NH4+ Association and Proton Transfer Reactions With a Series of Organic Molecules

Compendium of the Reactions of H3O+ With Selected Ketones of Relevance to Breath Analysis Using Proton Transfer Reaction Mass Spectrometry

Styrene radical cations for chemical ionization mass spectrometry analyses of monoterpene hydrocarbons

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