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Scientific Articles - PTR-MS Bibliography

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Found 51 results
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2016
[1717] Klein, F., S. M. Platt, N. J. Farren, A. Detournay, E. A. Bruns, C. Bozzetti, K. R. Daellenbach, D. Kilic, N. K. Kumar, S. M. Pieber, et al., "Characterization of Gas-Phase Organics Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry: Cooking Emissions.", Environ Sci Technol, vol. 50, pp. 1243–1250, Feb, 2016.
Link: http://dx.doi.org/10.1021/acs.est.5b04618
Abstract
<p>Cooking processes produce gaseous and particle emissions that are potentially deleterious to human health. Using a highly controlled experimental setup involving a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), we investigate the emission factors and the detailed chemical composition of gas phase emissions from a broad variety of cooking styles and techniques. A total of 95 experiments were conducted to characterize nonmethane organic gas (NMOG) emissions from boiling, charbroiling, shallow frying, and deep frying of various vegetables and meats, as well as emissions from vegetable oils heated to different temperatures. Emissions from boiling vegetables are dominated by methanol. Significant amounts of dimethyl sulfide are emitted from cruciferous vegetables. Emissions from shallow frying, deep frying and charbroiling are dominated by aldehydes of differing relative composition depending on the oil used. We show that the emission factors of some aldehydes are particularly large which may result in considerable negative impacts on human health in indoor environments. The suitability of some of the aldehydes as tracers for the identification of cooking emissions in ambient air is discussed.</p>
[1716] Schuhfried, E., J. {Sánchez Del Pulgar}, M. Bobba, R. Piro, L. Cappellin, T. D. Märk, and F. Biasioli, "Classification of 7 monofloral honey varieties by PTR-ToF-MS direct headspace analysis and chemometrics.", Talanta, vol. 147, pp. 213–219, Jan, 2016.
Link: http://dx.doi.org/10.1016/j.talanta.2015.09.062
Abstract
<p>Honey, in particular monofloral varieties, is a valuable commodity. Here, we present proton transfer reaction-time of flight-mass spectrometry, PTR-ToF-MS, coupled to chemometrics as a successful tool in the classification of monofloral honeys, which should serve in fraud protection against mispresentation of the floral origin of honey. We analyzed 7 different honey varieties from citrus, chestnut, sunflower, honeydew, robinia, rhododendron and linden tree, in total 70 different honey samples and a total of 206 measurements. Only subtle differences in the profiles of the volatile organic compounds (VOCs) in the headspace of the different honeys could be found. Nevertheless, it was possible to successfully apply 6 different classification methods with a total correct assignment of 81-99% in the internal validation sets. The most successful methods were stepwise linear discriminant analysis (LDA) and probabilistic neural network (PNN), giving total correct assignments in the external validation sets of 100 and 90%, respectively. Clearly, PTR-ToF-MS/chemometrics is a powerful tool in honey classification.</p>
[1822] Chandra, B.P.., and V. Sinha, "Contribution of post-harvest agricultural paddy residue fires in the N.W. Indo-Gangetic Plain to ambient carcinogenic benzenoids, toxic isocyanic acid and carbon monoxide", Environment International, vol. 88, pp. 187–197, mar, 2016.
Abstract
<p>In the north west Indo-Gangetic Plain (N.W.IGP), large scale post-harvest paddy residue fires occur every year during the months of October&ndash;November. This anthropogenic perturbation causes contamination of the atmospheric environment with adverse impacts on regional air quality posing health risks for the population exposed to high concentrations of carcinogens such as benzene and toxic VOCs such as isocyanic acid. These gases and carbon monoxide are known to be emitted from biomass fires along with acetonitrile. Yet no long-term in-situ measurements quantifying the impact of this activity have been carried out in the N.W. IGP. Using high quality continuous online in-situ measurements of these gases at a strategic downwind site over a three year period from 2012 to 2014, we demonstrate the strong impact of this anthropogenic emission activity on ambient concentrations of these gases. In contrast to the pre-paddy harvest period, excellent correlation of benzenoids, isocyanic acid and CO with acetonitrile (a biomass burning chemical tracer); (r &ge; 0.82) and distinct VOC/acetonitrile emission ratios were observed for the post-paddy harvest period which was also characterized by high ambient concentrations of these species. The average concentrations of acetonitrile (1.62 &plusmn; 0.18 ppb), benzene (2.51 &plusmn; 0.28 ppb), toluene (3.72 &plusmn; 0.41 ppb), C8-aromatics (2.88 &plusmn; 0.30 ppb), C9-aromatics (1.55 &plusmn; 0.19 ppb) and CO (552 &plusmn; 113 ppb) in the post-paddy harvest periods were about 1.5 times higher than the annual average concentrations. For isocyanic acid, a compound with both primary and secondary sources, the concentration in the post-paddy harvest period was 0.97 &plusmn; 0.17 ppb. The annual average concentrations of benzene, a class A carcinogen, exceeded the annual exposure limit of 1.6 ppb at NTP mandated by the National Ambient Air Quality Standard of India (NAAQS). We show that mitigating the post-harvest paddy residue fires can lower the annual average concentration of benzene and ensure compliance with the NAAQS. Calculations of excessive lifetime cancer risk due to benzene amount to 25 and 10 per million inhabitants for children and adults, respectively, exceeding the USEPA threshold of 1 per million inhabitants. Annual exposure to isocyanic acid was close to 1 ppb, the concentration considered to be sufficient to enhance risks for cardiovascular diseases and cataracts. This study makes a case for urgent mitigation of post-harvest paddy residue fires as the unknown synergistic effect of multi-pollutant exposure due to emissions from this anthropogenic source may be posing grave health risks to the population of the N.W. IGP.</p>
2015
[1644] Stojić, A.., S. S Stojić, A.. Šoštarić, L.. Ilić, Z.. Mijić, and S.. Rajšić, "Characterization of VOC sources in an urban area based on PTR-MS measurements and receptor modelling.", Environ Sci Pollut Res Int, May, 2015.
Link: http://dx.doi.org/10.1007/s11356-015-4540-5
Abstract
<p>In this study, the concentrations of volatile organic compounds were measured by the use of proton transfer reaction mass spectrometry, together with NO x , NO, NO2, SO2, CO and PM10 and meteorological parameters in an urban area of Belgrade during winter 2014. The multivariate receptor model US EPA Unmix was applied to the obtained dataset resolving six source profiles, which can be attributed to traffic-related emissions, gasoline evaporation/oil refineries, petrochemical industry/biogenic emissions, aged plumes, solid-fuel burning and local laboratories. Besides the vehicle exhaust, accounting for 27.6&nbsp;% of the total mixing ratios, industrial emissions, which are present in three out of six resolved profiles, exert a significant impact on air quality in the urban area. The major contribution of regional and long-range transport was determined for source profiles associated with petrochemical industry/biogenic emissions (40&nbsp;%) and gasoline evaporation/oil refineries (29&nbsp;%) using trajectory sector analysis. The concentration-weighted trajectory model was applied with the aim of resolving the spatial distribution of potential distant sources, and the results indicated that emission sources from neighbouring countries, as well as from Slovakia, Greece, Poland and Scandinavian countries, significantly contribute to the observed concentrations.</p>
[1763] Kaser, L.., T.. Karl, B.. Yuan, R.. L. Mauldin, C.. A. Cantrell, A.. B. Guenther, E.. G. Patton, A.. J. Weinheimer, C.. Knote, J.. Orlando, et al., "Chemistry-turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere", Geophysical Research Letters, vol. 42, pp. 10894–10903, Dec, 2015.
Link: http://n2t.net/ark:/85065/d7gq709d
Abstract
<p>The hydroxyl radical (OH) is the most important oxidant in the atmosphere and the primary sink for isoprene, the dominant volatile organic compound emitted by vegetation. Recent research on the atmospheric oxidation capacity in isoprene-dominated environments has suggested missing radical sources leading to significant overestimation of the lifetime of isoprene. Here we report, for the first time, a comprehensive experimental budget of isoprene in the planetary boundary layer based on airborne flux measurements along with in situ OH observations in the Southeast and Central U.S. Our findings show that surface heterogeneity of isoprene emissions lead to a physical separation of isoprene and OH resulting in an effective slowdown in the chemistry. Depending on surface heterogeneity, the intensity of segregation (Is) could locally slow down isoprene chemistry up to 30%. The effect of segregated reactants in the planetary boundary layer on average has an influence on modeled OH radicals that is comparable to that of recently proposed radical recycling mechanisms.</p>
[1645] Ciesa, F., I. Höller, W. Guerra, J. Berger, J. {Dalla Via}, and M. Oberhuber, "Chemodiversity in the Fingerprint Analysis of Volatile Organic Compounds (VOCs) of 35 Old and 7 Modern Apple Cultivars Determined by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) in Two Different Seasons.", Chem Biodivers, vol. 12, pp. 800–812, May, 2015.
Link: http://dx.doi.org/10.1002/cbdv.201400384
Abstract
<p>Volatile organic compounds (VOCs) are chemical species that play an important role in determining the characteristic aroma and flavor of fruits. Apple (Malus &times; domestica Borkh.) cultivars differ in their aroma and composition of VOCs. To determine varietal differences in the aroma profiles, VOCs emitted by 7 modern and 35 old apple cultivars were analyzed using Proton Transfer Reaction Mass Spectrometry (PTR-MS). PTR-MS is a rapid, reproducible, and non-destructive spectrometric technique for VOC analysis of single fruits, developed for direct injection analysis. In the present study, we analyzed the differences in the emission of VOCs from single fruits at harvest and after a storage period of 60&plusmn;10 days, followed by 3 d of shelf life. Our results show that VOC profile differences among apple cultivars were more pronounced after storage than at harvest. Furthermore, chemodiversity was higher in old cultivars compared to modern cultivars, probably due to their greater genetic variability. Our data highlight the importance of storage and shelf life are crucial for the development of the typical aroma and flavor of several apple cultivars. The validity of the method is demonstrated by comparison of two different harvest years.</p>
2014
[1566] Stockwell, C.. E., P.. R. Veres, J.. Williams, and R.. J. Yokelson, "Characterization of biomass burning smoke from cooking fires, peat, crop residue and other fuels with high resolution proton-transfer-reaction time-of-flight mass spectrometry", Atmospheric Chemistry and Physics Discussions, vol. 14, pp. 22163–22216, 2014.
Link: http://dx.doi.org/10.5194/acpd-14-22163-2014
Abstract
<p>We deployed a high-resolution proton-transfer-reaction time-of-flight mass spectrom-eter (PTR-TOF-MS) to measure biomass burning emissions from peat, crop-residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experi-ment (FLAME-4) laboratory campaign. A combination of gas standards calibrations and 5 composition sensitive, mass dependent calibration curves were applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign best identities to most major &quot;exact masses&quot; including many high molecular mass species. Using these methods ap-proximately 80&ndash;96 % of the total NMOC mass detected by PTR-TOF-MS and FTIR was 10 positively or tentatively identified for major fuel types. We report data for many rarely measured or previously unmeasured emissions in several compound classes including aromatic hydrocarbons, phenolic compounds, and furans; many of which are suspected secondary organic aerosol precursors. A large set of new emission factors (EFs) for a range of globally significant biomass fuels is presented. Measurements show that 15 oxygenated NMOCs accounted for the largest fraction of emissions of all compound classes. In a brief study of various traditional and advanced cooking methods, the EFs for these emissions groups were greatest for open 3-stone cooking in comparison to their more advanced counterparts. Several little-studied nitrogen-containing organic compounds were detected from many fuel types that together accounted for 0.1&ndash;8.7 % 20 of the fuel nitrogen and some may play a role in new particle formation.</p>
[1465] Sinha, V., V. Kumar, and C. Sarkar, "Chemical composition of pre-monsoon air in the Indo-Gangetic Plain measured using a new PTR-MS and air quality facility: high surface ozone and strong influence of biomass burning", Atmos. Chem. Phys., vol. 14, pp. 5921-5941, 2014.
Link: http://www.atmos-chem-phys.net/14/5921/2014/acp-14-5921-2014.html
Abstract
<p>One seventh of the world population lives in the Indo&ndash;Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia. Yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides is not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India&#39;s first high sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and meteorological station, was used to quantify in-situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (N. W. IGP). Westerly winds arriving at high wind speeds (5&ndash;20 m s&minus;1) in the pre-monsoon season at the site, were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May 2012 ranged from 1.2&ndash;1.7 nmol mol&minus;1 for aromatic VOCs, 5.9&ndash;37.4 nmol mol&minus;1 for the oxygenated VOCs, 1.4 nmol mol&minus;1 for acetonitrile, 1.9 nmol mol&minus;1 for isoprene, 567 nmol mol&minus;1 for carbon monoxide, 57.8 nmol mol&minus;1 for ozone, 11.5 nmol mol&minus;1 for nitrogen oxides, 7.3 nmol mol&minus;1 for sulphur dioxide, 104 μg m&minus;3 for PM2.5 and 276 μg m&minus;3 for PM10. By analyzing the one minute in-situ data with meteorological parameters and applying chemical tracers (e.g. acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning activity caused massive increases (&gt; 3 times of baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant source for oxygenated VOCs and isoprene (r2 with acetonitrile &ge; 0.5 for night-time data), which is remarkable in terms of atmospheric chemistry implications. Surface ozone exceeded the 8 h national ambient air quality limit of 100 μg O3 m&minus;3 on a daily basis, except for 17 May 2012, when a severe dust storm event (PM2.5 &gt; 800 μg m&minus;3; PM10 &gt; 2700 μg m&minus;3) characterized by long range transport from the west impacted the site. The novel dataset and results point to occurrence of high primary emissions of reactive VOCs. They also highlight the urgent need for establishing more comprehensive observational facilities in the IGP to constrain the spatial and seasonal variability of atmospheric chemical constituents. Such efforts will enable mechanistic level understanding of the in-situ chemical processes controlling formation of surface ozone, a necessary step for effective ozone mitigation and improvement of the regional air quality.</p>
[1605] Taiti, C., C. Costa, P. Menesatti, D. Comparini, N. Bazihizina, E. Azzarello, E. Masi, and S. Mancuso, "Class-modeling approach to PTR-TOFMS data: a peppers case study.", J Sci Food Agric, May, 2014.
Link: http://dx.doi.org/10.1002/jsfa.6761
Abstract
<p>Proton transfer reaction-mass spectrometry (PTR-MS), in its recently developed implementation based on time-of-flight mass spectrometry (PTR-TOFMS), was used to rapidly determine the volatile compounds present in fruits of Capsicum spp.We analyzed the volatile organic compounds emission profile of freshly cut chili peppers belonging to three species and 33 different cultivars. PTR-TOFMS data, analyzed with appropriate and advanced multivariate class-modeling approaches, perfectly discriminated among the three species (100% correct classification in validation set). VIP (variable importance in projection) scores were used to select the 15 most important volatile compounds in discriminating the species. The best candidates for Capsicum spp. were compounds with measured m/z of 63.027, 101.096 and 107.050, which were, respectively, tentatively identified as dimethyl sulfide, hexanal and benzaldehyde.Based on the promising results, the possibility of introducing multivariate class-modeling techniques, different from the classification approaches, in the field of volatile compounds analyses is discussed. &copy; 2014 Society of Chemical Industry.</p>
[1544] Mueller, M.., T.. Mikoviny, S.. Feil, S.. Haidacher, G.. Hanel, E.. Hartungen, A.. Jordan, L.. Maerk, P.. Mutschlechner, R.. Schottkowsky, et al., "A compact PTR-ToF-MS instrument for airborne measurements of VOCs at high spatio-temporal resolution", Atmospheric Measurement Techniques Discussions, vol. 7, pp. 5533–5558, 2014.
Link: http://www.atmos-meas-tech-discuss.net/7/5533/2014/
Abstract
<p><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">Herein, we report on the development of a compact proton-transfer-reaction time-of-flight mass spectrometer for airborne measurements of volatile organic compounds (VOCs). The new instrument resolves isobaric ions with a mass resolving power (</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">/Δ</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">) of ~ 1000, provides accurate&nbsp;</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m/z</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">&nbsp;measurements (Δ</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">&nbsp;&lt; 3 mDa), records full mass spectra at 1 Hz and thus overcomes some of the major analytical deficiencies of quadrupole-MS based airborne instruments. 1 Hz detection limits for biogenic VOCs (isoprene, α-pinene), aromatic VOCs (benzene, toluene, xylenes) and ketones (acetone, methyl ethyl ketone) range from 0.05 to 0.12 ppbV, making the instrument well-suited for fast measurements in the continental boundary layer. The instrument detects and quantifies VOCs in locally confined plumes (&lt; 1km) which improves our capability of characterizing emission sources and atmospheric processing within plumes. A deployment during the NASA 2013 DISCOVER-AQ mission generated high vertical and horizontal resolution in situ data of VOCs and ammonia for validation of satellite retrievals and chemistry transport models.</span></p>
[1790] Müller, M., T. Mikoviny, S. Feil, S. Haidacher, G. Hanel, E. Hartungen, A. Jordan, L. Märk, P. Mutschlechner, R. Schottkowsky, et al., "A compact PTR-ToF-MS instrument for airborne measurements of volatile organic compounds at high spatiotemporal resolution", Atmospheric Measurement Techniques, vol. 7, pp. 3763–3772, 2014.
Link: http://www.atmos-meas-tech.net/7/3763/2014/
Abstract
<p>Herein, we report on the development of a compact proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for airborne measurements of volatile organic compounds (VOCs). The new instrument resolves isobaric ions with a mass resolving power (m/Δm) of &nbsp;1000, provides accurate m/z measurements (Δm &lt; 3 mDa), records full mass spectra at 1 Hz and thus overcomes some of the major analytical deficiencies of quadrupole-MS-based airborne instruments. 1 Hz detection limits for biogenic VOCs (isoprene, α total monoterpenes), aromatic VOCs (benzene, toluene, xylenes) and ketones (acetone, methyl ethyl ketone) range from 0.05 to 0.12 ppbV, making the instrument well-suited for fast measurements of abundant VOCs in the continental boundary layer. The instrument detects and quantifies VOCs in locally confined plumes (&lt; 1 km), which improves our capability of characterizing emission sources and atmospheric processing within plumes. A deployment during the NASA 2013 DISCOVER-AQ mission generated high vertical- and horizontal-resolution in situ data of VOCs and ammonia for the validation of satellite retrievals and chemistry transport models.</p>
[1701] Maja, M. M., A. Kasurinen, P. Yli-Pirilä, J. Joutsensaari, T. Klemola, T. Holopainen, and J. K. Holopainen, "Contrasting responses of silver birch VOC emissions to short- and long-term herbivory.", Tree Physiol, vol. 34, pp. 241–252, Mar, 2014.
Link: http://dx.doi.org/10.1093/treephys/tpt127
Abstract
<p>There is a need to incorporate the effects of herbivore damage into future models of plant volatile organic compound (VOC) emissions at leaf or canopy levels. Short-term (a few seconds to 48 h) changes in shoot VOC emissions of silver birch (Betula pendula Roth) in response to feeding by geometrid moths (Erannis defoliaria Hübner) were monitored online by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). In addition, two separate field experiments were established to study the effects of long-term foliage herbivory (FH, 30-32 days of feeding by geometrids Agriopis aurantiaria (Clerck) and E. defoliaria in two consecutive years) and bark herbivory (BH, 21 days of feeding by the pine weevil (Hylobius abietis L.) in the first year) on shoot and rhizosphere VOC emissions of three silver birch genotypes (gt14, gt15 and Hausjärvi provenance). Online monitoring of VOCs emitted from foliage damaged by geometrid larvae showed rapid bursts of green leaf volatiles (GLVs) immediately after feeding activity, whereas terpenoid emissions had a tendency to gradually increase during the monitoring period. Long-term FH caused transient increases in total monoterpene (MT) emissions from gt14 and sesquiterpene (SQT) emissions from Hausjärvi provenance, mainly in the last experimental season. In the BH experiment, genotype effects were detected, with gt14 trees having significantly higher total MT emissions compared with other genotypes. Only MTs were detected in the rhizosphere samples of both field experiments, but their emission rates were unaffected by genotype or herbivory. The results suggest that silver birch shows a rapid VOC emission response to short-term foliage herbivory, whereas the response to long-term foliage herbivory and bark herbivory is less pronounced and variable at different time points.</p>
2013
[Kohl2013] Kohl, I., J. Herbig, J. Dunkl, A. Hansel, M. Daniaux, and M. Hubalek, "Chapter 6 - Smokers Breath as Seen by Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS)", Volatile Biomarkers, Boston, Elsevier, pp. 89 - 116, 2013.
Link: http://www.sciencedirect.com/science/article/pii/B9780444626134000064
Abstract
Abstract Proton-transfer-reaction time-of-flight mass spectrometry has been employed in a 12&#xa0;months breath gas analysis study to describe the breath composition of 19 cigarette smoking and 53 non-smoking women. The most prevalent constituents were acetone (1.8&#xa0;ppmv), methanol (310&#xa0;ppbv), isoprene (280&#xa0;ppbv), ethanol (130&#xa0;ppbv), acetaldehyde (90&#xa0;ppbv) and acetic acid (70&#xa0;ppbv). Smokers showed the largest signal increase in acetonitrile (ratio smoker/non-smoker 29), benzene (ratio 11), 2-methylfuran (ratio 8) and 2,5-dimethylfuran (ratio 7). Calibration gas measurements allowed the instruments performance regarding precision and accuracy of ion mass-to-charge, m/z, and concentration accuracy measurement to be assessed. The standard deviation of the concentration measurements was 14% or smaller (with the exception of ethanol) with no trend in this variation of sensitivity. The limit of detection (LOD) lay in the sub ppbv range, based on an integration time of 2&#xa0;s. The m/z accuracy was better than 0.0016 (or less than 29&#xa0;ppm of the ion mass) throughout the study. The standard deviation of the measured m/z was less than 0.0025 and the coefficient of variation was less than 29&#xa0;ppm. Keywords PTR-TOF-MS, Smokers’ breath, Breath volatile organic compounds, \{VOCs\}
[1668] Sekimoto, K., S. Inomata, H. Tanimoto, A. Fushimi, Y. Fujitani, K. Sato, and H. Yamada, "Characterization of nitromethane emission from automotive exhaust", Atmospheric Environment, vol. 81, pp. 523–531, Dec, 2013.
Link: http://dx.doi.org/10.1016/j.atmosenv.2013.09.031
Abstract
<p>We carried out time-resolved experiments using a proton-transfer-reaction mass spectrometer and a chassis dynamometer to characterize nitromethane emission from automotive exhaust. We performed experiments under both cold-start and hot-start conditions, and determined the dependence of nitromethane emission on vehicle velocity and acceleration/deceleration as well as the effect of various types of exhaust-gas treatment system. We found that nitromethane emission was much lower from a gasoline car than from diesel trucks, probably due to the reduction function of the three-way catalyst of the gasoline car. Diesel trucks without a NOx reduction catalyst using hydrocarbons produced high emissions of nitromethane, with emission factors generally increasing with increasing acceleration at low vehicle velocities.</p>
[1513] Holzinger, R.., A.. H. Goldstein, P.. L. Hayes, J.. L. Jimenez, and J.. Timkovsky, "Chemical evolution of organic aerosol in Los Angeles during the CalNex 2010 study", Atmospheric Chemistry and Physics, vol. 13, pp. 10125–10141, Oct, 2013.
Link: http://dx.doi.org/10.5194/acp-13-10125-2013
Abstract
<p>During the CalNex study (15 May to 16 June 2010) a large suite of instruments was operated at the Los Angeles area ground supersite to characterize the sources and atmospheric processing of atmospheric pollution. The thermal-desorption proton-transfer-reaction mass-spectrometer (TD-PTR-MS) was deployed to an urban area for the first time and detected 691 organic ions in aerosol samples, the mean total concentration of which was estimated as 3.3 μg m&minus;3. Based on comparison to total organic aerosol (OA) measurements, we estimate that approximately 50% of the OA mass at this site was directly measured by the TD-PTR-MS. Based on correlations with aerosol mass spectrometer (AMS) OA components, the ions were grouped to represent hydrocarbon-like OA (HOA), local OA (LOA), semi-volatile oxygenated OA (SV-OOA), and low volatility oxygenated OA (LV-OOA). Mass spectra and thermograms of the ion groups are mostly consistent with the assumed sources and/or photochemical origin of the OA components. The mass spectra of ions representing the primary components HOA and LOA included the highest m/z, consistent with their higher resistance to thermal decomposition, and they were volatilized at lower temperatures (&nbsp; 150 &deg;C). Photochemical ageing weakens C-C bond strengths (also resulting in chemical fragmentation), and produces species of lower volatility (through the addition of functional groups). Accordingly the mass spectra of ions representing the oxidized OA components (SV-OOA, and LV-OOA) lack the highest masses and they are volatilized at higher temperatures (250&ndash;300 &deg;C). Chemical parameters like mean carbon number (nC), mean carbon oxidation state (OSC), and the atomic ratios O / C and H / C of the ion groups are consistent with the expected sources and photochemical processing of the aerosol components. Our data suggest that chemical fragmentation gains importance over functionalization as photochemical age of OA increases. Surprisingly, the photochemical age of OA decreases during the daytime hours, demonstrating the importance of rapid production of new (photochemically young) SV-OOA during daytime. The PTR detects higher organic N concentrations than the AMS, the reasons for which are not well understood and cannot be explained by known artifacts related to PTR or the AMS. The median atomic N / C ratio (6.4%) of the ion group representing LV-OOA is a factor 2 higher than N / C of any other ion group. This suggests a multiphase chemical source involving ammonium ions is contributing to LV-OOA.</p>
[1590] Déléris, I., A. Saint-Eve, E. Sémon, H. Guillemin, E. Guichard, I. Souchon, and J-L. { Le Quéré}, "Comparison of direct mass spectrometry methods for the on-line analysis of volatile compounds in foods.", J Mass Spectrom, vol. 48, pp. 594–607, May, 2013.
Link: http://dx.doi.org/10.1002/jms.3199
Abstract
<p>For the on-line monitoring of flavour compound release, atmospheric pressure chemical ionization (APCI) and proton transfer reaction (PTR) combined to mass spectrometry (MS) are the most often used ionization technologies. APCI-MS was questioned for the quantification of volatiles in complex mixtures, but direct comparisons of APCI and PTR techniques applied on the same samples remain scarce. The aim of this work was to compare the potentialities of both techniques for the study of in vitro and in vivo flavour release. Aroma release from flavoured aqueous solutions (in vitro measurements in Teflon bags and glass vials) or flavoured candies (in vivo measurements on six panellists) was studied using APCI- and PTR-MS. Very similar results were obtained with both techniques. Their sensitivities, expressed as limit of detection of 2,5-dimethylpyrazine, were found equivalent at 12&thinsp;ng/l air. Analyses of Teflon bag headspace revealed a poor repeatability and important ionization competitions with both APCI- and PTR-MS, particularly between an ester and a secondary alcohol. These phenomena were attributed to dependency on moisture content, gas/liquid volume ratio, proton affinities and product ion distribution, together with inherent drawbacks of Teflon bags (adsorption, condensation of water and polar molecules). Concerning the analyses of vial headspace and in vivo analyses, similar results were obtained with both techniques, revealing no competition phenomena. This study highlighted the equivalent performances of APCI-MS and PTR-MS for in vitro and in vivo flavour release investigations and provided useful data on the problematic use of sample bags for headspace analyses.</p>
[1699] Trefz, P., M. Schmidt, P. Oertel, J. Obermeier, B. Brock, S. Kamysek, J. Dunkl, R. Zimmermann, J. K. Schubert, and W. Miekisch, "Continuous real time breath gas monitoring in the clinical environment by proton-transfer-reaction-time-of-flight-mass spectrometry.", Anal Chem, vol. 85, pp. 10321–10329, Nov, 2013.
Link: http://dx.doi.org/10.1021/ac402298v
Abstract
<p>Analysis of volatile organic compounds (VOCs) in breath holds great promise for noninvasive diagnostic applications. However, concentrations of VOCs in breath may change quickly, and actual and previous uptakes of exogenous substances, especially in the clinical environment, represent crucial issues. We therefore adapted proton-transfer-reaction-time-of-flight-mass spectrometry for real time breath analysis in the clinical environment. For reasons of medical safety, a 6 m long heated silcosteel transfer line connected to a sterile mouth piece was used for breath sampling from spontaneously breathing volunteers and mechanically ventilated patients. A time resolution of 200 ms was applied. Breath from mechanically ventilated patients was analyzed immediately after cardiac surgery. Breath from 32 members of staff was analyzed in the post anesthetic care unit (PACU). In parallel, room air was measured continuously over 7 days. Detection limits for breath-resolved real time measurements were in the high pptV/low ppbV range. Assignment of signals to alveolar or inspiratory phases was done automatically by a matlab-based algorithm. Quickly and abruptly occurring changes of patients&#39; clinical status could be monitored in terms of breath-to-breath variations of VOC (e.g. isoprene) concentrations. In the PACU, room air concentrations mirrored occupancy. Exhaled concentrations of sevoflurane strongly depended on background concentrations in all participants. In combination with an optimized inlet system, the high time and mass resolution of PTR-ToF-MS provides optimal conditions to trace quick changes of breath VOC profiles and to assess effects from the clinical environment.</p>
[1698] Righettoni, M.., A.. Schmid, A.. Amann, and S.. E. Pratsinis, "Correlations between blood glucose and breath components from portable gas sensors and PTR-TOF-MS.", J Breath Res, vol. 7, pp. 037110, Sep, 2013.
Link: http://dx.doi.org/10.1088/1752-7155/7/3/037110
Abstract
<p>Acetone is one of the most abundant volatile compounds in the human breath and might be important for monitoring diabetic patients. Here, a portable acetone sensor consisting of flame-made, nanostructured, Si-doped WO3&nbsp;sensing films was used to analyse the end tidal fraction of the breath (collected in Tedlar bags) from eight healthy volunteers after overnight fasting (morning) and after lunch (afternoon). After breath sampling, the gaseous components were also analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), and each person&#39;s blood glucose level was measured. The portable sensor accurately detected the presence of acetone with fast response/recovery times (&lt;12&nbsp;s) and a high signal-to-noise ratio. Statistical analysis of the relationship between the PTR-TOF-MS measurements of breath gases (e.g., acetone, isoprene, ethanol and methanol), sensor response and the blood glucose level was performed for both sampling periods. The best correlations were found after overnight fasting (morning): in particular, between blood glucose level and breath acetone (Pearson&#39;s 0.98 and Spearman&#39;s 0.93). Whereas the portable sensor response correlated best with the blood glucose (Pearson&#39;s 0.96 and Spearman&#39;s 0.81) and breath acetone (Pearson&#39;s 0.92 and Spearman&#39;s 0.69).</p>
[Pollien2013] Pollien, P., F. Viton, and B. Le Révérend, "Coupling of in-mouth physical phenomena with nosespace analysis; a new method for understanding aroma release and perception from liquids", CONFERENCE SERIES, pp. 209, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
2012
[Sinha2012a] Sinha, V., J. Williams, JM. Diesch, F. Drewnick, M. Martinez, H. Harder, E. Regelin, D. Kubistin, H. Bozem, Z. Hosaynali-Beygi, et al., "Constraints on instantaneous ozone production rates and regimes during DOMINO derived using in-situ OH reactivity measurements", Atmospheric Chemistry and Physics, vol. 12, no. 15: Copernicus GmbH, pp. 7269–7283, 2012.
Link: http://www.atmos-chem-phys.net/12/7269/2012/acp-12-7269-2012.pdf
Abstract
In this study air masses are characterized in terms of their total OH reactivity which is a robust measure of the "reactive air pollutant loading". The measurements were performed during the DOMINO campaign (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) held from 21/11/2008 to 08/12/2008 at the Atmospheric Sounding Station – El Arenosillo (37.1° N–6.7° W, 40 m a.s.l.). The site was frequently impacted by marine air masses (arriving at the site from the southerly sector) and air masses from the cities of Huelva (located NW of the site), Seville and Madrid (located NNE of the site). OH reactivity values showed strong wind sector dependence. North eastern "continental" air masses were characterized by the highest OH reactivities (average: 31.4 ± 4.5 s−1; range of average diel values: 21.3–40.5 s−1), followed by north western "industrial" air masses (average: 13.8 ± 4.4 s−1; range of average diel values: 7–23.4 s−1) and marine air masses (average: 6.3 ± 6.6 s−1; range of average diel values: below detection limit −21.7 s−1), respectively. The average OH reactivity for the entire campaign period was  18 s−1 and no pronounced variation was discernible in the diel profiles with the exception of relatively high values from 09:00 to 11:00 UTC on occasions when air masses arrived from the north western and southern wind sectors. The measured OH reactivity was used to constrain both diel instantaneous ozone production potential rates and regimes. Gross ozone production rates at the site were generally limited by the availability of NOx with peak values of around 20 ppbV O3 h−1. Using the OH reactivity based approach, derived ozone production rates indicate that if NOx would no longer be the limiting factor in air masses arriving from the continental north eastern sector, peak ozone production rates could double. We suggest that the new combined approach of in-situ fast measurements of OH reactivity, nitrogen oxides and peroxy radicals for constraining instantaneous ozone production rates, could significantly improve analyses of upwind point sources and their impact on regional ozone levels.
[Trowbridge2012] Trowbridge, A. M., D. Asensio, A. S. D. Eller, D. A. Way, M. J. Wilkinson, J-P. Schnitzler, R. B. Jackson, and R. K. Monson, "Contribution of various carbon sources toward isoprene biosynthesis in poplar leaves mediated by altered atmospheric CO2 concentrations.", PLoS One, vol. 7, no. 2: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, United States of America. amy.m.trowbridge@gmail.com, pp. e32387, 2012.
Link: http://dx.doi.org/10.1371/journal.pone.0032387
Abstract
Biogenically released isoprene plays important roles in both tropospheric photochemistry and plant metabolism. We performed a (13)CO(2)-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of recently assimilated photosynthate into isoprene emitted from poplar (Populus x canescens) trees grown and measured at different atmospheric CO(2) concentrations. This is the first study to explicitly consider the effects of altered atmospheric CO(2) concentration on carbon partitioning to isoprene biosynthesis. We studied changes in the proportion of labeled carbon as a function of time in two mass fragments, M41(+), which represents, in part, substrate derived from pyruvate, and M69(+), which represents the whole unlabeled isoprene molecule. We observed a trend of slower (13)C incorporation into isoprene carbon derived from pyruvate, consistent with the previously hypothesized origin of chloroplastic pyruvate from cytosolic phosphenolpyruvate (PEP). Trees grown under sub-ambient CO(2) (190 ppmv) had rates of isoprene emission and rates of labeling of M41(+) and M69(+) that were nearly twice those observed in trees grown under elevated CO(2) (590 ppmv). However, they also demonstrated the lowest proportion of completely labeled isoprene molecules. These results suggest that under reduced atmospheric CO(2) availability, more carbon from stored/older carbon sources is involved in isoprene biosynthesis, and this carbon most likely enters the isoprene biosynthesis pathway through the pyruvate substrate. We offer direct evidence that extra-chloroplastic rather than chloroplastic carbon sources are mobilized to increase the availability of pyruvate required to up-regulate the isoprene biosynthesis pathway when trees are grown under sub-ambient CO(2).
2011
[FeilbergTavsNyord2011] Nyord}, A. {Feilberg, M. N. Ã. ¸rrega Hansen, and S. Lindholst, "Chemical evaluation of odor reduction by soil injection of animal manure.", J Environ Qual, vol. 40, no. 5: Dep. of Biosystem Engineering, Faculty of Science and Technology, Aarhus Univ., Denmark. anders.feilberg@agrsci.dk, pp. 1674–1682, 2011.
Link: http://dx.doi.org/10.2134/jeq2010.0499
Abstract
Field application of animal manure is a major cause of odor nuisance in the local environment. Therefore, there is a need for methods for measuring the effect of technologies for reducing odor after manure application. In this work, chemical methods were used to identify key odorants from field application of pig manure based on experiments with surface application by trailing hoses and soil injection. Results from three consecutive years of field trials with full-scale equipment are reported. Methods applied were: membrane inlet mass spectrometry (MIMS), proton-transfer-reaction mass spectrometry (PTR-MS), gold-film hydrogen sulfide (H?S) detection, all performed on site, and thermal desorption gas chromatography with mass spectrometry (TD-GC/MS) based on laboratory analyses of field samples. Samples were collected from a static flux chamber often used for obtaining samples for dynamic olfactometry. While all methods were capable of detecting relevant odorants, PTR-MS gave the most comprehensive results. Based on odor threshold values, 4-methylphenol, H?S, and methanethiol are suggested as key odorants. Significant odorant reductions by soil injection were consistently observed in all trials. The flux chamber technique was demonstrated to be associated with critical errors due to compound instabilities in the chamber. This was most apparent for H?S, on a time scale of a few minutes, and on a longer time scale for methanethiol.
[1506] Wolfe, G.. M., J.. A. Thornton, N.. C. Bouvier-Brown, A.. H. Goldstein, J.-H.. Park, M.. McKay, D.. M. Matross, J.. Mao, W.. H. Brune, B.. W. LaFranchi, et al., "The Chemistry of Atmosphere-Forest Exchange (CAFE) Model ¬タモ Part 2: Application to BEARPEX-2007 observations", Atmospheric Chemistry and Physics, vol. 11, pp. 1269–1294, Feb, 2011.
Link: http://nature.berkeley.edu/ahg/pubs/Wolf et al acp-11-1269-2011.pdf
Abstract
<p>In a companion paper, we introduced the Chemistry of Atmosphere-Forest Exchange (CAFE) model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we apply CAFE to noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007). In this work we evaluate the CAFE modeling approach, demonstrate the significance of in-canopy chemistry for forest-atmosphere exchange and identify key shortcomings in the current understanding of intra-canopy processes. CAFE generally reproduces BEARPEX-2007 observations but requires an enhanced radical recycling mechanism to overcome a factor of 6 underestimate of hydroxyl (OH) concentrations observed during a warm (&nbsp;29 &deg;C) period. Modeled fluxes of acyl peroxy nitrates (APN) are quite sensitive to gradients in chemical production and loss, demonstrating that chemistry may perturb forest-atmosphere exchange even when the chemical timescale is long relative to the canopy mixing timescale. The model underestimates peroxy acetyl nitrate (PAN) fluxes by 50% and the exchange velocity by nearly a factor of three under warmer conditions, suggesting that near-surface APN sinks are underestimated relative to the sources. Nitric acid typically dominates gross dry N deposition at this site, though other reactive nitrogen (NOy) species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be &nbsp;30% lower than the gross depositional flux. CAFE under-predicts ozone fluxes and exchange velocities by &nbsp;20%. Large uncertainty in the parameterization of cuticular and ground deposition precludes conclusive attribution of non-stomatal fluxes to chemistry or surface uptake. Model-measurement comparisons of vertical concentration gradients for several emitted species suggests that the lower canopy airspace may be only weakly coupled with the upper canopy. Future efforts to model forest-atmosphere exchange will require a more mechanistic understanding of non-stomatal deposition and a more thorough characterization of in-canopy mixing processes.</p>
[Simpraga2011] Šimpraga, M., H. Verbeeck, M. Demarcke, É. Joó, O. Pokorska, C. Amelynck, N. Schoon, J. Dewulf, H. Van Langenhove, B. Heinesch, et al., "Clear link between drought stress, photosynthesis and biogenic volatile organic compounds in Fagus sylvatica L.", Atmospheric Environment, vol. 45, no. 30: Elsevier, pp. 5254–5259, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S1352231011006996
Abstract
Direct plant stress sensing is the key for a quantitative understanding of drought stress effects on biogenic volatile organic compound (BVOC) emissions. A given level of drought stress might have a fundamentally different effect on the BVOC emissions of different plants. For the first time, we continuously quantified the level of drought stress in a young potted beech (Fagus sylvatica L.) with a linear variable displacement transducer (LVDT) installed at stem level in combination with simultaneous measurements of BVOC emissions and photosynthesis rates at leaf level. This continuous set of measurements allowed us to examine how beech alters its pattern of photosynthesis and carbon allocation to BVOC emissions (mainly monoterpenes, MTs) and radial stem growth during the development of drought stress. We observed an increasing-decreasing trend in the MT emissions as well as in the fraction of assimilated carbon re-emitted back into the atmosphere (ranging between 0.14 and 0.01%). We were able to link these dynamics to pronounced changes in radial stem growth, which served as a direct plant stress indicator. Interestingly, we detected a sudden burst in emission of a non-identified, non-MT BVOC species when drought stress was acute (i.e. pronounced negative stem growth). This burst might have been caused by a certain stress-related green leaf volatile, which disappeared immediately upon re-watering and thus the alleviation of drought stress. These results highlight that direct plant stress sensing creates opportunities to understand the overall complexity of stress-related BVOC emissions.
[Simpraga2011a] Šimpraga, M., H. Verbeeck, M. Demarcke, É. Joó, C. Amelynck, N. Schoon, J. Dewulf, H. Van Langenhove, B. Heinesch, M. Aubinet, et al., "Comparing monoterpenoid emissions and net photosynthesis of beech ( Fagus sylvatica L.) in controlled and natural conditions", Atmospheric Environment, vol. 45, no. 17: Elsevier, pp. 2922–2928, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S1352231011000884
Abstract
<p>Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of the plant&rsquo;s carbon (C) budget, they play an important role in atmospheric chemistry for example as a precursor of tropospheric ozone. We performed a study comparing BVOC emissions of European beech (Fagus sylvatica L.) in controlled and natural environmental conditions. A young and adult beech tree was exposed to short-term temperature variations in growth room conditions and in an experimental forest, respectively. This study attempts to clarify how short-term temperature variations between days influenced the ratio between monoterpenoid (MT) emissions and net photosynthesis (Pn). Within a temperature range of 17&ndash;27 &deg;C and 13&ndash;23 &deg;C, the MT/Pn carbon ratio increased 10&ndash;30 fold for the growth room and forest, respectively. An exponential increasing trend between MT/Pn C ratio and air temperature was observed in both conditions. Beech trees re-emitted a low fraction of the assimilated C back into the atmosphere as MT: 0.01&ndash;0.12% and 0.01&ndash;0.30% with a temperature rise from 17 to 27 &deg;C and 13&ndash;23 &deg;C in growth room and forest conditions, respectively. However, the data showed that the MT/Pn C ratio of young and adult beech trees responded significantly to changes in temperature.</p>

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Selected PTR-MS related Reviews

F. Biasioli, C. Yeretzian, F. Gasperi, T. D. Märk: PTR-MS monitoring of VOCs and BVOCs in food science and technology, Trends in Analytical Chemistry 30 (7) (2011).
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J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257.
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W. Lindinger, A. Hansel, A. Jordan: Proton-transfer-reaction mass spectrometry (PTR–MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev. 27 (1998), 347-375.
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Lists with PTR-MS relevant publications of the University of Innsbruck can be found here: Atmospheric and indoor air chemistry, IMR, Environmental Physics and Nano-Bio-Physics

 

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