PTR-MS Studies of the Reactions of H3O+ with a Number of Deuterated

International Journal of Mass Spectrometry 436 (2019) 65–70

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International Journal of Mass Spectrometry

jou rnal homepage: www.elsevier.com/locate/ijms

Full Length Article

PTR-MS studies of the reactions of H3O with a number of deuterated

volatile organic compounds and the subsequent sequential reactions

of the primary product ions with water under normal and humid drift

tube conditions: Implications for use of deuterated compounds for

breath analysis

a,b,∗ c a,d e

Paweł Mochalski , Soﬁa Mirmigkou , Karl Unterkoﬂer , Philipp Sulzer ,

a,f g

Christopher A. Mayhew , Tilmann D. Märk

Institute for Breath Research, Leopold-Franzens-Universitat¨ Innsbruck, Rathausplatz 4, A-6850 Dornbirn, Austria

Institute of Chemistry, Jan Kochanowski University, Swi´ etokrzyska˛ 15G, PL-25406 Kielce, Poland

Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK

Vorarlberg University of Applied Sciences, Hochschulstr. 1, A-6850 Dornbirn, Austria

IONICON Analytik Gesellschaft m.b.H., Eduard-Bodem-Gasse 3, A-6020 Innsbruck, Austria

Molecular Physics Group, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universitat¨ Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria

a r t i c l e i n f o a b s t r a c t

Article history: Product ion distributions resulting from the primary reactions of H3O with nine D-labeled volatile

Received 4 July 2018

organic compounds and the subsequent sequential reactions with H2O have been determined using a

Received in revised form 16 October 2018

Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF 8000 (IONICON Analytik GmbH))

Accepted 1 November 2018

at various reduced electric ﬁeld (E/N) values ranging from 80 up to 150 Td and for two different abso-

Available online 12 November 2018

lute humidity levels of air sample < 0.1% and 5%. The speciﬁc D-labeled compounds used in this study

are acetone-d6, toluene-d8, benzene-d6, ethanol-d (C2H5OD), ethanol-d2 (CH3CD2OH), ethanol-d6, 2-

Keywords:

propanol-d8, 2-propanol-d3 (CD3CH(OH)CH3), and isoprene-d5 (CH2CHC(CD2)CD3). With the exception

Deuterated volatile organic compounds

PTR-TOF-MS of the two 2-propanol compounds, non-dissociative proton transfer is the dominant primary reaction

+ pathway. For 2-propanol-d and 2-propanol-d the major primary reaction channel involved is dissocia-

H3O reactions 8 3

Fragmentation patterns tive proton transfer. However, unlike their undeuterated counterparts, the primary product ions undergo

D/H isotopic exchange subsequent deuterium/hydrogen isotope exchange reactions with the ever present water in the drift tube,

the extent of which of course depends on the humidity within that tube. This exchange leads to the gen-

eration of various isotopologue product ions, the product ion branching percentages of which are also

dependent on the humidity in the drift tube. This results in complex mass spectra and the distribution

of product ions leads to issues of reduced sensitivity and accuracy. However, the effect of D/H exchange

considerably varies between the compounds under study. In the case of acetone-d6 it is very weak (<

1%), because the exchange process is not facile when the deuterium is in the methyl functional group.

In comparison, the H3O / benzene-d6 (C6D6) reaction and sequential reactions with water result in the

production of the isotopologue ions C6Dn(H7-n) (where n = 0–6). Changing the value of E/N and/or the

humidity in the drift tube considerably affects the amount of the isotope exchange reactions and hence

the resulting sequential product ion distributions. An important conclusion of the ﬁndings from this

work is that care must be taken in the choice of an exogenous deuterated compound for use in breath

pharmacokinetic studies using proton transfer reaction mass spectrometry; otherwise the resulting D/H

exchange processes impose interpretative problems.

1. Introduction

∗

Corresponding author. The human body emits hundreds of volatile organic compounds

E-mail address: [email protected] (P. Mochalski). (VOCs) via breath, skin emanation, and other bodily ﬂuids such

https://doi.org/10.1016/j.ijms.2018.11.007

66 P. Mochalski et al. / International Journal of Mass Spectrometry 436 (2019) 65–70

as urine, saliva, or sweat [1,2]. These compounds are frequently pared to the cleaner chemical environment of the ﬂow tube in a

deﬁned as the human volatilome [3]. While some of these VOCs SIFT.

are of endogenous origin, other can stem from exogenous sources With regards to SIFT studies, and in relation to the biological

such as diet, environmental exposure, or microbiota activity. Col- aspects presented in this study, we comment that there has been

lectively, they form a chemical ﬁngerprint containing information a SIFT H3O investigation of the kinetics and isotope patterns of

on biochemical processes ongoing in both healthy and diseased ethanol and acetaldehyde head space emissions from yeast fermen-

human organisms. It has been reported that pathological processes, tation of glucose-6,6-d2 by Smith et al. [14].

such as metabolic disorders, cancer, or other diseases can inﬂuence

the VOCs proﬁle by producing new VOCs, or by altering the ratio of

the VOCs that are produced normally by the human organism. This 2. Experimental

approach opens up new applied areas of research such as the poten-

tial use of trace volatiles for diagnosing, screening and monitoring 2.1. Materials and standard mixtures

diseases, tracking of microbiota activity, or exposure to environ-

mental toxins [4–6]. Despite this huge potential, the use of these Single-compound calibration mixtures were prepared from

patterns within a clinical setting remains rather limited. The main pure liquid substances. The majority of the pure substances

unresolved issue is the poor understanding of the sources, behav- were purchased from Sigma-Aldrich (Austria); acetone-d6 (99.9%),

ior and metabolic fate of potential disease markers in the human toluene-d8 (99%), benzene-d6 (99.6%), ethanol-d (99%), ethanol-d2

organism. (98%), ethanol-d6 (99.5%), 2-propanol-d8 (99.5%), and 2-propanol-

Isotope labelling of volatiles could partially address these d3 (98%). Isoprene-d5 (98%) was obtained from Campro Scientiﬁc

problems. C-labeled compounds are commonly used in breath GmbH (Germany).

gas analysis. Important examples are the C-urea breath test Gas standard mixtures were prepared using the procedure out-

13 13

for H. pylori detection [7] and the C-dextromethorphan/ C- lined in Mochalski et al. [15]. The product ion distributions were

pantoprazol breath tests aiming at evaluating the enzyme activities investigated using 2 distinct concentrations of each compound to

13 13 12

[8,9]. In these tests breath CO2 is targeted and the CO2/ CO2 ensure that there were no secondary ion-molecule reactions with

ratio is used to evaluate the results. Alternatively, compounds of the analyte, i.e. that the distributions of the product ion channels

15 18

interest could be labeled with other isotopes such as N, O, did not change in high purity air at concentrations of approximately

or deuterium (D). In particular, the latter labelling received some 50 and 100 ppb and at two absolute humidity levels of < 0.1% and 5%,

attention in breath gas analysis to track metabolites of some the latter approximately corresponding to that of exhaled breath.

VOCs with Proton Transfer Reaction - Mass Spectrometry (PTR-MS)

[10,11], or to validate exhalation kinetics models [12]. However,

these PTR-MS studies have only investigated deuterated ethanol or 2.2. PTR-TOF-MS analysis

acetone. There have been no systematic studies of other deuter-

ated compounds and in particular the effects of humidity in the PTR-MS is an analytical device that has applications rang-

drift (reaction) region of the PTR-MS instrument have not been ing from atmospheric chemistry through to homeland security

investigated. Thus the reactions of hydronium ions with deuterated [16–22], but it really comes into its own for monitoring rapid

volatile organic compounds and subsequent reactions of the pri- changes in volatile concentrations via its real-time capabilities.

mary ions in the conditions of the PTR-TOF-MS reactors are poorly These real-time analytical techniques are particularly attractive for

understood and the present study is intended to help ﬁll this gap tracking rapid short-time changes in the human volatilome [14,15],

in our knowledge. which can provide invaluable information on normal and abnormal

The main goal of this paper is to present details on the prod- processes occurring in the body [12,23–27]. This is due to its ver-

uct ion distributions, which will be a combination of the primary satility, excellent sensitivity and (for ToF MS) high mass resolving

product ion(s) resulting from the reactions of H3O and the sub- power (up to 5000 m/m). In particular, the last feature supports

sequent sequential product ions involving nine deuterated organic studies to separate isobaric compounds producing nominally the

compounds, over a reduced electric ﬁeld range of 80–150 T d and at same m/z product ions.

two different absolute humidity levels of < 0.1% and 5%, the latter The H3O reactions with the deuterated compounds and the

approximately corresponding to that of exhaled breath using a PTR- subsequent reactions of the primary product ions with H2O were

TOF-MS instrument. The compounds selected for this investigation investigated using a PTR-TOF 8000 (Ionicon Analytik GmbH). The

are acetone-d6, toluene-d8, benzene-d6, ethanol-d (C2H5OD), settings of the ion source used in this study were as follows: ion

ethanol-d2 (CH3CD2OH), ethanol-d6, 2-propanol-d8, 2-propanol- source current 3 mA, source voltage 140 V, source-out voltage 30 V,

d3 (CD3CH(OH)CH3), and isoprene-d5 (CH2CHC(CD2)CD3). and source valve opening 50%. At these values and a puriﬁed air

◦

Earlier examples of isotope exchange processes have been sample in the drift tube operating at 130 Td, a temperature of 60 C

reported by Adams et al. [13] using a selected ion ﬂow tube (SIFT). and a pressure of 2.4 mbar, the major other reagent ions in the drift

+ + +

Of interest to this work, they reported the reactions of H3O with tube relative to that of the H3O reagent ion were NO with 0.2-

+ + +

D2O and D3O with H2O. These two ion-molecule reactions were 0.3%, O2 with 2% and H3O .H2O with 3%. However, at low reduced

found to proceed with reaction rate coefﬁcients close to their col- electric ﬁelds (< 100 Td), H3O .H2O, formed from an association

lisional values and that the product ion distributions are statistical reaction of H3O with H2O, becomes the dominant reagent ion.

owing to the production of thoroughly mixed intermediates (com- Note that a dry buffer gas in the drift tube of a PTR-MS instru-

plete scrambling of the H and D atoms within the intermediate ment does not mean that it is operating under dry conditions,

complex). Such scrambling is unlikely given the complexity of because of diffusion of water vapour from the hollow cathode.

the analytes involved in this study, because in every intermediate We will, therefore, refer to this as “normal” operating conditions.

deuterons/protons are attached to different atoms and not just to When a water saturated buffer gas is used, we will refer to that as

oxygen atoms, unlike the earlier work. However, it should be appre- operating the drift tube under “humid” conditions.

ciated that unlike SIFT, PTR-MS is not designed to be a research The product ion distributions were investigated for eight dis-

instrument, but is an analytical device, and hence it is not always tinct E/N ratios in the reaction tube ranging from 80 to 150 Td

possible to clearly identify primary reaction processes owing to the with incremental changes of 10 Td by adjusting the drift tube volt-

more complex conditions found in the drift tube of a PTR-MS com- age. The ion mass (m/z) calibration was regularly checked using the

P. Mochalski et al. / International Journal of Mass Spectrometry 436 (2019) 65–70 67

18 +

presence of the impurity ions of known m/z values, namely: H3 O quent reactions with H2O in the drift tube results in the observed

+ +

(21.0221) and NO2 (45.9924). isotopologue C6DnH7-n (n = 0–6).

The standard mixtures of deuterated compounds were intro- In the case of fully deuterated acetone, isotopic exchange is

duced into the drift tube of the PTR-TOF-MS instrument at a steady not facile with the methyl groups and hence the only dominant

◦

ﬂow rate of 20 mL/min via a two-meter-long, heated (60 C) PEEK ion observed is the protonated parent in both dry and humid

(Polyetheretherketone) transfer line reducing the surface adsorp- conditions. The product ion distributions of the H3O /isoprene-d5

tion of water vapor and the deuterated compounds under study. reaction is more complicated owing to some fragmentation follow-

The mass spectral scans converted from the drift times of the ing proton transfer. However the data show that isotope exchange

ions in the TOF analyzer ranged from approximately m/z 2.7 to 500 is not signiﬁcant, as is apparent from the comparison of the dry and

and were acquired in a time of 30 s by co-adding 750 000 single humid air samples, with protonated isoprene-d5 being the domi-

␮

40- s long TOF-MS extractions recorded at a sampling frequency nating ion with abundances ranging from 80% to 55% for 80 Td

of 10 GHz. The actual mass resolution in the present experiment and 150 Td respectively. The main isotope exchange channel cor-

obtained from the detected peaks was ≈ 4300 at m/z 100. The total responds to the single D/H exchange and its abundance is spread

duration of a single measurement was 3 min, which corresponds around 10% for all investigated reduced electric ﬁeld values, and

to 6 mass spectra acquired per single E/N ratio. The average of the the multiple D/H exchange channels are weak (< 3%).

ion signal levels at each m/z value from these 6 spectra was used In a PTR-Quad-MS study by Brown et al. [21], it is reported

to calculate the percentages of the product ions for each of the that for 2-propanol C3H7 is a major product ion. Similarly, for

+ +

H3O /deuterated VOC reactions. 2-propanol-d8, the dominant product ion observed here is C3D7 ,

resulting from the loss of HDO from the protonated parent. How-

ever, owing to D/H exchange with the water in the drift tube of 3. Results

the PTR-MS, C3DnH7-n (n = 0–3, 5–7) product ions are observed,

Table 1 lists the percentage distributions of the product ions thereby reducing the intensity of the primary product ion. C3D4H3

resulting from the primary reactions of H3O with the 9 deuterated must be formed, but it is not reported in the table because no sig-

volatiles included in this study and the subsequent sequential prod- niﬁcant intensity (< 1%) of this ion was observed. Similarly, for

uct ion-water reactions. Thus, the product ion distributions include 2-propanol-d3, C3D3H4 is the dominant ion and then sequential

the combination of primary ions and the product ions resulting isotope exchange results ultimately in C3H7 . The protonated par-

from a series of sequential reactions with water in the drift tube ent is observed, but only with a small intensity in the dry air case,

of the PTR-MS under the operational conditions used in this study. and the D/H exchange results in observable intensities of C3D3H6O

+ +

These percentages refer to the average of intensities obtained for and C3DH8O for 2-propanol-d3 and C3D7H2O for 2-propanol-d8.

the two distinct concentrations using the average of 6 spectra for For the higher humidity studies, and in particular at low E/N values,

each deuterated compound. a dramatic rise in the associated branching percentages is observed

A review of Table 1 immediately reveals that despite the single for these ions. This is because of the higher concentration of the

ionization mechanism via exothermic proton transfer the product H3O .H2O reagent ions in the drift tube resulting from the humid

ion distributions are relatively complex. This is due to the sequen- air sample at any given E/N compared to the dry air sample. Proton

tial deuterium-hydrogen exchange reactions between product ions transfer from H3O .H2O to the 2-propanol-d3 and d8 will be less

and neutral water in the drift tube leading to several isotopo- energetic than from H3O , resulting in less fragmentation. Given

−1

logue ions. However, the amount of exchange considerably varies that the proton afﬁnity of 2-propanol (793 kJ mol ) is slightly less

−1

between compounds under study and depends on reaction time than that of the water dimer (H2O)2 (808 kJ mol ) [22], proton

(which is inversely proportional to the reduced electric ﬁeld) and transfer is driven by the reduced electric ﬁeld. In the work by Brown

humidity. This is clearly demonstrated for toluene, for both the et al. with 2-propanol, at high E/N (> 115 Td) the product ions C3H5

+ +

dry and humid case the protonated parent C7D8H percentage and C3H3 were observed with reasonable intensities. In this study,

increases with increasing E/N owing to the reduced reaction time only 2-propanol-d3 resulted in fragment ions beyond C3DnH7-n

for secondary reactions, but in the humid sample the percentages (n = 0–3) with reasonable intensities. This illustrates how impor-

are lower owing to the increased concentration of water in the drift tant it is to determine product ion branching percentages for a given

tube available for D/H exchange. Reaction of C7DnH9-n (n = 4–8) PTR-MS instrument.

with water terminates once the deuterium atoms in the benzene For the deuterated ethanols, the product ions observed are

ring have been exchanged (n = 3), i.e. exchange of the deuterium predominantly C2DmHnO , where m + n = 7. For ethanol-d, only

atoms on the methyl group does not take place. m = 0 and n = 7 is observed, i.e. no C2H5ODH is observed with any

Our results show that the primary reaction does not result in a signiﬁcant intensity. Obviously it is formed, but D/H exchange is

statistical decomposition. For example, in the case of toluene-d8, if facile when the deuterium atom is bound to oxygen in the hydroxyl

complete scrambling of the H and D atoms within the intermediate group. This is also the reason why no C2D5ODH is observed from

+ + +

complex C7D8.H3O occurred, the primary reaction of H3O with the reaction of H3O with ethanol-d6. For ethanol-d2, a disso-

toluene-d8 would proceed via three channels leading to C7D8H ciative proton transfer product ion channel is observed resulting

+ + +

+ H2O, C7D7H2 + HDO, and C7D6H3 + D2O, with probabilities in C2DnH5-n (n = 1–2). This agrees well with the work of Brown

of 5.5%, 43.6% and 50.9%, respectively. That the ﬁrst channel is et al. [21]. However, Brown et al. in addition reported signiﬁcant

found to dominate for the dry air measurements, with a proba- product ion branching percentages for [ROH-H2]H (e.g. at an E/N

bility of 48%, implies that following proton transfer from H3O , the of 138 Td they give a percentage branching percentage of 17%

protonated toluene-d8 rapidly dissociates, i.e. the dissociation life- for this product ion). We observe the equivalent product ion for

time leading to C7D8H + H2O is far less than the lifetime of the ethanol-d but only signiﬁcantly at the maximum E/N used in this

intermediate complex. Although some scrambling cannot be ruled study, giving a product ion branching percentage of only 6% for

out, the results suggest that proton transfer is the dominant pri- both the dry and humid air samples. Similarly, for ethanol-d6,

mary reaction process, and that all other observed product ions are the product ion C2D4HO resulting from the elimination of HD

predominantly a result of sequential reactions with water in the following proton transfer is observed, with a product ion branching

drift tube. The same is true for benzene-d6, for which the product percentage that reaches 23% at an E/N of 150 Td in the dry air

ion distributions for the primary reaction occurred via statistical sample. For the humid air sample its intensity is reduced to 14%

decomposition. The H3O / benzene-d6 (C6D6) reaction and subse- at the highest E/N value. This could be the result of changes in

68 P. Mochalski et al. / International Journal of Mass Spectrometry 436 (2019) 65–70 an

of *

Error [mTh] 0.8 1.1 0.9 0.8 0.8 0.6 0.8 0.4 0.2 0.6 0.4 1.4 1.1 0.2 0.7 0.9 1.1 0.1 0.2 0.5 0.1 0.4 1.8 2.1 2.1 0.6 0.4 3.2 0.4 0.6 2.5 1.5 0.5 0.2 1.3 0.6 0.3 0.5 0.5 0.6 0.8 24 1.3 0.8 1.3 1.1 1.2 1.5 1.5 0.8 0.7 0.4 0.3 1.1 1.1 0.9 1.0 1.9 1.0 tube

[Th] (reaction)

85.0916 84.0851 83.079 82.0728 81.0665 80.0605 79.0540 65.0870 64.0808 46.0366 74.1014 73.0941 72.0882 71.0828 45.0649 44.0589 43.0528 42.0454 68.1091 50.0982 49.0923 48.0858 46.0718 45.0652 44.0590 43.0554 64.0838 62.0684 46.0732 45.0667 44.0585 43.0532 42.0465 41.0393 40.0300 70.0922 52.0808 51.0743 50.0680 49.0585 34.0697 33.0621 32.0567 31.0509 67.0715 49.0611 48.0548 31.0502 30.0439 65.0603 47.0490 45.0336 29.0388 Measured m/z 101.1195 100.1133 99.1072 98.1008 97.0936 96.0883 drift

the

gas

[Th]

Expected m/z 85.0924 84.0862 83.0799 82.0736 81.0673 80.0611 79.0548 65.0874 64.0810 46.0372 74.1018 73.0955 72.0893 71.0830 45.0642 44.058 43.0517 42.0454 68.1093 50.0987 49.0924 48.0862 46.0736 45.0673 44.0611 43.0548 64.0842 62.0716 46.0736 45.0673 44.061 43.0547 42.047 41.0391 40.0313 70.0916 52.0811 51.0748 50.0685 49.0591 34.0705 33.0858 32.0580 31.0517 67.0728 49.0622 48.0560 31.0517 30.0454 65.0595 47.0497 45.0340 29.0391 101.1206 100.1144 99.1081 98.1018 97.0955 96.0893 buffer

the

150 4 7 8 12 20 26 22 98 1 1 69 9 3 2 1 5 5 6 1 27 23 15 8 8 9 10 0 7 34 16 7 10 13 10 3 0 70 9 2 14 5 0 3 0 3 77 12 7 2 1 79 6 14 38 35 19 7 2 0 as

140 3 5 6 8 15 26 37 98 1 1 76 10 3 1 1 3 2 2 1 25 25 21 11 7 6 6 1 6 36 23 11 8 8 6 1 0 68 11 3 11 4 0 3 1 3 74 14 6 3 1 81 4 13 31 34 22 10 3 1 samples

air

5%)

130 3 4 4 5 9 20 56 98 1 1 79 11 3 1 1 3 1 1 1 23 25 24 13 7 4 3 1 6 35 29 15 6 4 3 1 0 63 15 6 8 4 0 3 1 3 70 18 6 3 2 84 2 12 24 31 26 14 5 1 (AH

120 2 3 2 3 5 12 73 98 1 1 80 11 3 1 1 2 0 1 2 22 23 24 15 8 4 3 2 6 33 30 17 6 3 2 1 0 54 18 11 8 3 0 3 2 3 67 20 6 4 3 85 1 11 16 25 27 21 10 2 humid

and

110 1 3 1 1 3 5 86 98 1 1 80 12 3 1 1 2 0 0 4 25 19 21 16 9 4 3 4 8 32 27 18 6 2 1 2 1 49 18 15 8 3 1 3 2 4 74 13 6 3 3 86 0 10 9 17 24 27 18 6 dry

using

100 1 4 1 0 2 1 90 98 1 1 79 12 3 1 1 2 0 0 8 36 16 14 13 8 4 2 9 9 36 20 15 5 2 1 2 1 62 14 10 3 3 2 3 1 5 81 5 6 2 4 86 0 9 5 10 16 26 28 15 [Td]

water

90 1 6 1 0 2 1 89 98 1 1 78 13 4 2 1 2 0 0 15 55 13 5 5 4 2 1 18 9 50 10 7 3 1 1 2 2 78 7 3 1 4 2 2 0 6 83 3 6 2 5 86 0 9 4 7 8 18 32 32 air with

Humid 80 2 7 1 0 2 1 87 98 1 1 74 15 6 3 1 2 0 0 20 63 11 2 2 1 1 1 25 6 57 6 2 2 1 0 1 2 83 4 1 1 4 2 2 0 7 83 2 6 2 6 86 0 8 4 6 3 7 24 56 reactions

150 35 33 20 9 3 1 0 98 1 1 55 8 3 2 4 13 11 5 0 40 9 1 28 14 5 2 0 6 34 3 12 22 9 7 7 0 65 3 0 23 5 0 4 0 0 75 2 17 8 0 80 6 13 79 17 2 0 1 0

subsequent

140 31 31 22 11 4 1 0 98 1 1 67 9 3 2 3 8 5 3 0 47 14 2 21 10 3 2 0 5 45 6 10 20 8 3 3 0 66 4 0 21 5 0 4 1 0 75 2 15 8 0 81 4 15 79 18 2 0 1 0 and

Td.

130 27 29 23 14 6 2 0 98 1 1 75 10 3 1 2 5 2 1 0 55 19 4 13 5 2 2 0 5 58 8 8 13 5 1 1 0 69 5 1 17 4 0 4 1 0 75 2 15 8 0 80 3 17 77 19 2 1 1 0 150

compounds

120 22 25 23 17 9 3 0 98 1 1 78 11 3 1 1 4 0 1 0 60 22 5 8 3 1 2 0 5 68 10 5 8 2 1 0 0 70 8 1 12 4 0 4 1 0 76 3 13 9 0 81 2 18 75 20 3 1 1 0 80

from

110 18 20 22 19 14 6 1 98 1 1 79 11 3 1 1 4 0 1 0 62 23 5 6 2 0 2 0 5 71 11 4 6 1 0 0 0 66 14 3 7 3 1 5 1 0 76 5 11 9 0 81 1 18 72 23 4 1 1 0 deuterated

ranging

with 100 13 15 18 20 18 11 3 98 1 1 79 11 3 1 1 3 0 1 0 62 23 5 5 1 0 2 0 5 72 11 4 6 1 0 0 0 62 17 5 4 3 3 4 2 0 75 6 10 9 0 82 0 18 66 26 6 1 1 0 +

O values 3

H [Td]

E/N of

90 10 11 13 18 21 18 8 98 1 1 79 11 3 1 1 3 0 1 1 63 23 5 5 1 0 2 1 5 73 11 3 6 1 0 0 0 67 13 5 3 3 3 4 1 0 76 6 10 8 0 82 0 17 58 30 10 2 1 0 for 0%AH

air peak.

reactions 80 48 33 14 4 1 0 7 8 9 13 20 25 18 98 1 1 79 11 3 1 1 3 0 1 2 65 21 5 4 1 0 2 2 5 73 11 3 5 1 0 0 0 75 8 3 2 4 3 3 1 0 78 5 10 6 1 83 0 16 Dry

the

instrument

methanol +

+ O) + from O) 3

8000

3 O) + + + + + + + channel 3

+ + + + O O O O O O O(H O + + + + + + + + + + + + + + + + + + + + + + + + 2 3 4 5 6 + 2 3 4 5 2 4 5 6 7 + 2 3 2 + 2 4 5 6 O 4 5 2 3 4 + 2 3 4 5 O 3 + + + + + + + + 6 4 6 8 6 6 4 O(H O O + + + + + + + H H H H H H H H H H H HO H O H H H H H H H H H H H H H H H HO(H H H H HO H H H H H H + + 7 7 7 6 5 4 6 7 5 5 8 7 6 5 4 3 6 5 4 3 2 6 5 3 5 4 3 2 4 3 2 7 7 6 5 3 2 3 3 2 5 5 4 3 4 5 4 3 2 2 2 2 D D D D D D D D D D D DH H D D D D D D D D D D DH D D D D D D DH H D DH D D DH H H H H D D D D D D D D D D D DH D DH H H H H resulting background 7 7 7 7 7 7 6 6 6 6 6 6 6 3 3 2 5 5 5 5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 PTR-TOF

Reaction C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C a

GmbH

3 3 8 3 )CD 2

distributions

5 6

6 8 6 2

purity Analytik

overlapped

ion 2

OD OC O OD 1 D

CHC(CD CD 5 CH(OH)CH 6 6 8 5

7 2 3 3 D D D D H peak C 99% 2037-26-5 6 3 3 2 2 * CAS C 99.6% 1076-43-3 Acetone-d C 99.9% 666-52-4 Isoprene-d CH 98% 2-propanol-d C 99.5% 22739-76-0 2-propanol-d CD 98% 84809-71-2 Ethanol-d C 99.6% 1516-08-1 Ethanol-d CH 98% 1859-09-2 Ethanol-d C 99% 925-93-9 Compound Formula Toluene-d Benzene-d Table Product IONICON

P. Mochalski et al. / International Journal of Mass Spectrometry 436 (2019) 65–70 69

the effective temperature of the reagent ion-ethanol collision for agreement no. 644031 and through a Marie Skłodowska-Curie

a given E/N caused by the higher humidity present in the drift Actions Innovative Training Network “IMPACT” supported by the

tube. European Commission’s HORIZON 2020 Programme under Grant

Agreement Number 674911. PM and KU gratefully acknowledge

ﬁnancial support from the Austrian Science Fund (FWF) under grant

4. Discussion and conclusions

No. P24736-B23.

The rationale behind this study was to identify the product

ions resulting from the reactions of H3O ions with nine D-labeled References

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[1] A. Amann, De. Smith, Volatile Biomarkers Non-Invasive Diagnosis in

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Horizon 2020 research and innovation programme under grant

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