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2016
[1688] Breiev, K., K. M. M. Burseg, G. OConnell, E. Hartungen, S. S. Biel, X. Cahours, S. Colard, T. D. Maerk, and P. Sulzer, "An online method for the analysis of volatile organic compounds in electronic cigarette aerosol based on proton transfer reaction mass spectrometry", Rapid Commun. Mass Spectrom., vol. 30, pp. 691–697, Feb, 2016.
Link: http://dx.doi.org/10.1002/rcm.7487
Abstract
<p>Rationale Due to the recent rapid increase in electronic cigarette (e-cigarette) use worldwide, there is a strong scientific but also practical interest in analyzing e-cigarette aerosols. Most studies to date have used standardized but time-consuming offline technologies. Here a proof-of-concept for a fast online quantification setup based on proton transfer reaction mass spectrometry (PTR-MS) is presented. Methods The combination of a novel sampling interface with a time-of-flight PTR-MS instrument specially designed for three scenarios is introduced: (i) mainstream aerosol analysis (aerosol that the user inhales prior to exhalation), and analysis of exhaled breath following (ii) mouth-hold (no inhalation) and (iii) inhalation of e-cigarette aerosols. A double-stage dilution setup allows the various concentration ranges in these scenarios to be accessed. Results First, the instrument is calibrated for the three principal constituents of the e-cigarettes&#39; liquids, namely propylene glycol, vegetable glycerol and nicotine. With the double-stage dilution the instrument&#39;s dynamic range was easily adapted to cover the concentration ranges obtained in the three scenarios: 20&ndash;1100 ppmv for the mainstream aerosol characterisation; 4&ndash;300 ppmv for the mouth-hold; and 2 ppbv to 20 ppmv for the inhalation experiment. Conclusions It is demonstrated that the novel setup enables fast, high time resolution e-cigarette studies with online quantification. This enables the analysis and understanding of any puff-by-puff variations in e-cigarette aerosols. Large-scale studies involving a high number of volunteers will benefit from considerably higher sample throughput and shorter data processing times.</p>
[1819] Sarkar, C., V. Sinha, V. Kumar, M. Rupakheti, A. Panday, K. S. Mahata, D. Rupakheti, B. Kathayat, and M. G. Lawrence, "Overview of {VOC} emissions and chemistry from {PTR}-{TOF}-{MS} measurements during the {SusKat}-{ABC} campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley", Atmospheric Chemistry and Physics, vol. 16, pp. 3979–4003, mar, 2016.
Link: https://www.atmos-chem-phys.net/16/3979/2016/acp-16-3979-2016.pdf
Abstract
<p>The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley&ndash;Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012&ndash;2013, a comprehensive study was carried out to characterise the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs, by deploying a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) &ndash; the first such deployment in South Asia. In the study, 71 ion peaks (for which measured ambient concentrations exceeded the 2σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m ∕ Δm &thinsp;&gt;&thinsp; 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The concentration ranking in the average VOC mixing ratios during our wintertime deployment was acetaldehyde (8.8 ppb) &thinsp;&gt;&thinsp; methanol (7.4 ppb) &thinsp;&gt;&thinsp; acetone + propanal (4.2 ppb) &thinsp;&gt;&thinsp; benzene (2.7 ppb) &thinsp;&gt;&thinsp; toluene (1.5 ppb) &thinsp;&gt;&thinsp; isoprene (1.1 ppb) &thinsp;&gt;&thinsp; acetonitrile (1.1 ppb) &thinsp;&gt;&thinsp; C8-aromatics (&thinsp;&sim;&thinsp;1 ppb) &thinsp;&gt;&thinsp; furan (&thinsp;&sim;&thinsp;0.5 ppb) &thinsp;&gt;&thinsp; C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m ∕ z &thinsp;=&thinsp; 69.070) and furan (m ∕ z &thinsp;=&thinsp; 69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde (&thinsp;&sim;&thinsp; 9 ppb), acetonitrile (&thinsp;&sim;&thinsp; 1 ppb) and isoprene (&thinsp;&sim;&thinsp; 1 ppb) to be among the highest reported to date. Two &quot;new&quot; ambient compounds, namely formamide (m ∕ z &thinsp;=&thinsp; 46.029) and acetamide (m ∕ z &thinsp;=&thinsp; 60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust), which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile, which correlated strongly with acetonitrile (r2&thinsp;&gt;&thinsp;0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential. Based on known secondary organic aerosol (SOA) yields and measured ambient concentrations in the Kathmandu Valley, the relative SOA production potential of VOCs were benzene &thinsp;&gt;&thinsp; naphthalene &thinsp;&gt;&thinsp; toluene &thinsp;&gt;&thinsp; xylenes &thinsp;&gt;&thinsp; monoterpenes &thinsp;&gt;&thinsp; trimethylbenzenes &thinsp;&gt;&thinsp; styrene &thinsp;&gt;&thinsp; isoprene. The first ambient measurements from any site in South Asia of compounds with significant health effects such as isocyanic acid, formamide, acetamide, naphthalene and nitromethane have been reported in this study. Our results suggest that mitigation of intense wintertime biomass burning activities, in particular point sources such biomass co-fired brick kilns, would be important to reduce the emission and formation of toxic VOCs (such as benzene and isocyanic acid) in the Kathmandu Valley.</p>
[1713] Farré-Armengol, G., J. Penuelas, T. Li, P. Yli-Pirilä, I. Filella, J. Llusia, and J. D. Blande, "Ozone degrades floral scent and reduces pollinator attraction to flowers.", New Phytol, vol. 209, pp. 152–160, Jan, 2016.
Link: http://dx.doi.org/10.1111/nph.13620
Abstract
<p>In this work we analyzed the degradation of floral scent volatiles from Brassica nigra by reaction with ozone along a distance gradient and the consequences for pollinator attraction. For this purpose we used a reaction system comprising three reaction tubes in which we conducted measurements of floral volatiles using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) and GC-MS. We also tested the effects of floral scent degradation on the responses of the generalist pollinator Bombus terrestris. The chemical analyses revealed that supplementing air with ozone led to an increasing reduction in the concentrations of floral volatiles in air with distance from the volatile source. The results revealed different reactivities with ozone for different floral scent constituents, which emphasized that ozone exposure not only degrades floral scents, but also changes the ratios of compounds in a scent blend. Behavioural tests revealed that floral scent was reduced in its attractiveness to pollinators after it had been exposed to 120&nbsp;ppb O3 over a 4.5&nbsp;m distance. The combined results of chemical analyses and behavioural responses of pollinators strongly suggest that high ozone concentrations have significant negative impacts on pollination by reducing the distance over which floral olfactory signals can be detected by pollinators.</p>
2015
[1664] Zannoni, N.., V.. Gros, M.. Lanza, R.. Sarda, B.. Bonsang, C.. Kalogridis, S.. Preunkert, M.. Legrand, C.. Jambert, C.. Boissard, et al., "OH reactivity and concentrations of Biogenic Volatile Organic Compounds in a Mediterranean forest of downy oak trees", Atmos. Chem. Phys. Discuss., vol. 15, pp. 22047--22095, 2015.
Link: http://dx.doi.org/10.5194/acpd-15-22047-2015
Abstract
<p>Abstract. Understanding the processes between the biosphere and the atmosphere is challenged by the difficulty to determine with enough accuracy the composition of the atmosphere. Total OH reactivity, which is defined as the total loss of the hydroxyl radical in the atmosphere, has proved to be an excellent tool to identify indirectly the important reactive species in ambient air. High levels of unknown reactivity were found in several forests worldwide and were often higher than at urban sites. Such results demonstrated the importance of OH reactivity for characterizing two of the major unknowns currently present associated to forests: the set of primary emissions from the canopy to the atmosphere and biogenic compounds oxidation pathways. Previous studies also highlighted the need to quantify OH reactivity and missing OH reactivity at more forested sites. Our study presents results of a field experiment conducted during late spring 2014 at the forest site at the Observatoire de Haute Provence, OHP, France. The forest is mainly composed of downy oak trees, a deciduous tree species characteristic of the Mediterranean region. We deployed the Comparative Reactivity Method and a set of state-of-the-art techniques such as Proton Transfer Reaction-Mass Spectrometry and Gas Chromatography to measure the total OH reactivity, the concentration of volatile organic compounds and main atmospheric constituents at the site. We sampled the air masses at two heights: 2 m, i.e. inside the canopy, and 10 m, i.e. above the canopy, where the mean canopy height is 5 m. We found that the OH reactivity at the site mainly depended on the main primary biogenic species emitted by the forest, which was isoprene and to a lesser extent by its degradation products and long lived atmospheric compounds (up to 26 % during daytime). We determined that the daytime total measured reactivity equaled the calculated reactivity obtained from the concentrations of the compounds measured at the site. Hence, no significant missing reactivity is reported in this specific site, neither inside, nor above the canopy. However, during two nights we reported a missing fraction of OH reactivity up to 50 %, possibly due to unmeasured oxidation products. Our results confirm the weak intra canopy oxidation, already suggested in a previous study focused on isoprene fluxes. They also demonstrate how helpful can be the OH reactivity as a tool to clearly characterize the suite of species present in the atmosphere. We show that our result of reactivity is among the highest reported in forests worldwide and stress the importance to quantify OH reactivity at more and diverse Mediterranean forests.</p>
2014
[1722] "Omics in Soil Science", : Caister Academic Press, 2014.
Link: http://www.horizonpress.com/omics
Abstract
<p>Soil is a unique biological system with an abundant microflora and a very high microbial diversity capable of performing multiple key ecosystem functions. The detection of genes in soil has improved the knowledge of unculturable microorganisms and led to a greater understanding of potential soil metabolic pathways. Further advances in understanding soil functionality are being realised by harnessing omics technologies such as metagenomics, metatranscriptomics, proteomics and volatilomics. The next challenge of systems biology and functional genomics is to integrate the information from omic approaches to give a more complete picture of soil as a biological system. This volume presents the state-of-the-art of omic applications in soil science, a field that is advancing rapidly on many fronts. Distinguished authors describe the application of metagenomics, metatranscriptomics and proteomics to soil science. In particular the book covers the current and emerging omics techniques and the contribution of these approaches to a better assessment of soil functionality. The authors also explore the specific problems encountered in the application of various omics technologies to soil science and the future research requirements necessary to overcome the current limitations in this area. Topics covered include soil functional genomics, soil metagenomics, soil microbial ecology, soil metatranscriptomics, soil proteomics, soil volatilomics and soil proteogenomics. Omics techniques are also discussed in comparison with classical techniques. This book is both a practical guide and a recommended reference volume for all soil scientists.</p>
[1597] Szymczak, W., J. Rozman, V. Höllriegl, M. Kistler, S. Keller, D. Peters, M. Kneipp, H. Schulz, C. Hoeschen, M. Klingenspor, et al., "Online breath gas analysis in unrestrained mice by hs-PTR-MS.", Mamm Genome, vol. 25, pp. 129–140, Apr, 2014.
Link: http://dx.doi.org/10.1007/s00335-013-9493-8
Abstract
<p>The phenotyping of genetic mouse models for human disorders may greatly benefit from breath gas analysis as a noninvasive tool to identify metabolic alterations in mice. Phenotyping screens such as the German Mouse Clinic demand investigations in unrestrained mice. Therefore, we adapted a breath screen in which exhaled volatile organic compounds (VOCs) were online monitored by proton transfer reaction mass spectrometry (hs-PTR-MS). The source strength of VOCs was derived from the dynamics in the accumulation profile of exhaled VOCs of a single mouse in a respirometry chamber. A careful survey of the accumulation revealed alterations in the source strength due to confounders, e.g., urine and feces. Moreover changes in the source strength of humidity were triggered by changes in locomotor behavior as mice showed a typical behavioral pattern from activity to settling down in the course of subsequent accumulation profiles. We demonstrated that metabolic changes caused by a dietary intervention, e.g., after feeding a high-fat diet (HFD) a sample of 14 male mice, still resulted in a statistically significant shift in the source strength of exhaled VOCs. Applying a normalization which was derived from the distribution of the source strength of humidity and accounted for varying locomotor behaviors improved the shift. Hence, breath gas analysis may provide a noninvasive, fast access to monitor the metabolic adaptation of a mouse to alterations in energy balance due to overfeeding or fasting and dietary macronutrient composition as well as a high potential for systemic phenotyping of mouse mutants, intervention studies, and drug testing in mice.</p>
2013
[Fares2013] Fares, S., R. Schnitzhofer, X. Jiang, A. Guenther, A. Hansel, and F. Loreto, "Observations of diurnal to weekly variations of monoterpene-dominated fluxes of volatile organic compounds from Mediterranean forests: implications for regional modeling.", Environ Sci Technol, Sep, 2013.
Link: http://dx.doi.org/10.1021/es4022156
Abstract
The Estate of Castelporziano (Rome, Italy) hosts many ecosystems representative of Mediterranean vegetation, especially holm oak and pine forests, and dune vegetation. In this work, Basal Emission Factors (BEFs) of biogenic volatile organic compounds (BVOCs) obtained by Eddy Covariance in a field campaign using a Proton Transfer Reaction - Time of Flight - Mass Spectrometer (PTR-TOF-MS) were compared to BEFs reported in previous studies that could not measure fluxes in real-time. Globally, broadleaf forests are dominated by isoprene emissions, but these Mediterranean ecosystems are dominated by strong monoterpene emitters, as shown by the new BEFs. The original and new BEFs were used to parameterize the Model of Emissions of Gases and Aerosols from Nature (MEGAN v2.1), and model outputs were compared with measured fluxes. Results showed good agreement between modelled and measured fluxes when a model was used to predict radiative transfer and energy balance across the canopy. We then evaluated whether changes in BVOC emissions can affect the chemistry of the atmosphere and climate at a regional level. MEGAN was run together with the land surface model (Community Land Model, CLM v4.0) of the Community Earth System Model (CESM v1.0). Results highlighted that tropospheric ozone concentration and air temperature predicted from the model are sensitive to the magnitude of BVOC emissions, thus demonstrating the importance of adopting the proper BEF values for model parameterization.
[Gloess2013a] Gloess, A. N., A. Vietri, S. Bongers, T. Koziorowski, and C. Yeretzian, "On-line Analysis of the Coffee Roasting Process with PTR-ToF-MS: Evidence of Different Flavor Formation Dynamics for Different Coffee Varieties", CONFERENCE SERIES, pp. 166, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
[1667] Inomata, S., H. Tanimoto, Y. Fujitani, K. Sekimoto, K. Sato, A. Fushimi, H. Yamada, S. Hori, Y. Kumazawa, A. Shimono, et al., "On-line measurements of gaseous nitro-organic compounds in diesel vehicle exhaust by proton-transfer-reaction mass spectrometry", Atmospheric Environment, vol. 73, pp. 195–203, Jul, 2013.
Link: http://dx.doi.org/10.1016/j.atmosenv.2013.03.035
Abstract
<p>Nitro-organic compounds, some of which cause adverse health effects in humans, are emitted in diesel engine exhaust. Speciation and quantification of these nitro-organic compounds in diesel engine exhaust particles have been extensively conducted; however, investigations into the emissions of gaseous nitro-organic compounds in diesel engine exhaust have not. In the present study, the properties of gaseous nitro-organic compounds in diesel engine exhaust were investigated through time-resolved measurement with a proton-transfer-reaction mass spectrometer and a chassis dynamometer. Three diesel trucks were tested, each with a different type of exhaust-gas treatment system (i.e., aftertreatment). Among the nitro-organic compounds detected, the emission of nitromethane was commonly observed and found to be related to the emissions of carbon monoxide, benzene, and acetone. The emission of other nitro-organic compounds, such as nitrophenol, depended on the vehicle, possibly due to the type of aftertreatment installed.</p>
2012
[1530] Barmet, P.., J.. Dommen, P.. F. DeCarlo, T.. Tritscher, A.. P. Praplan, S.. M. Platt, A.. S. H. Prevot, N.. M. Donahue, and U.. Baltensperger, "OH clock determination by proton transfer reaction mass spectrometry at an environmental chamber", Atmos. Meas. Tech., vol. 5, pp. 647–656, Mar, 2012.
Link: http://dx.doi.org/10.5194/amt-5-647-2012
Abstract
<p>The hydroxyl free radical (OH) is the major oxidizing species in the lower atmosphere. Measuring the OH concentration is generally difficult and involves elaborate, expensive, custom-made experimental setups. Thus other more economical techniques, capable of determining OH concentrations at environmental chambers, would be valuable. This work is based on an indirect method of OH concentration measurement, by monitoring an appropriate OH tracer by proton transfer reaction mass spectrometry (PTR-MS). 3-pentanol, 3-pentanone and pinonaldehyde (PA) were used as OH tracers in α-pinene (AP) secondary organic aerosol (SOA) aging studies. In addition we tested butanol-d9 as a potential &quot;universal&quot; OH tracer and determined its reaction rate constant with OH: kbutanol-d9 = 3.4(&plusmn;0.88) &times; 10&minus;12 cm3 molecule&minus;1 s&minus;1. In order to make the chamber studies more comparable among each other as well as to atmospheric measurements we suggest the use of a chemical (time) dimension: the OH clock, which corresponds to the integrated OH concentration over time.</p>
[Sinha2012] Sinha, V., J. Williams, JM. Diesch, F. Drewnick, M. Martinez, H. Harder, E. Regelin, D. Kubistin, H. Bozem, Z. Hosaynali-Beygi, et al., "OH reactivity measurements in a coastal location in Southwestern Spain during DOMINO", Atmospheric Chemistry and Physics Discussions, vol. 12, no. 2: Copernicus GmbH, pp. 4979–5014, 2012.
Link: http://www.atmos-chem-phys-discuss.net/12/4979/2012/acpd-12-4979-2012.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 November 2008 to 8 December 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 −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.
[Crespo2012] Crespo, E., C. A. Hordijk, R. M. { de Graaf}, D. Samudrala, S. M. Cristescu, F. J. M. Harren, and N. M. { van Dam}, "On-line detection of root-induced volatiles in Brassica nigra plants infested with Delia radicum L. root fly larvae.", Phytochemistry, vol. 84: Life Science Trace Gas Facility, Institute of Molecules and Materials (IMM), Radboud University Nijmegen, Nijmegen, The Netherlands., pp. 68–77, Dec, 2012.
Link: http://dx.doi.org/10.1016/j.phytochem.2012.08.013
Abstract
Plants emit various volatile organic compounds (VOCs) upon herbivore attack. These VOC emissions often show temporal dynamics which may influence the behavior of natural enemies using these volatiles as cues. This study analyzes on-line VOC emissions by roots of Brassica nigra plants under attack by cabbage root fly larvae, Delia radicum. Root emitted VOCs were detected using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) and Gas Chromatography-Mass Spectrometry (GC-MS). These analyses showed that several sulfur containing compounds, such as methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and glucosinolate breakdown products, such as thiocyanates (TC) and isothiocyanates (ITC), were emitted by the roots in response to infestation. The emissions were subdivided into early responses, emerging within 1-6 h after infestation, and late responses, evolving only after 6-12 h. The marker for rapid responses was detected at m/z 60. The ion detected at m/z 60 was identified as thiocyanic acid, which is also a prominent fragment in some TC or ITC spectra. The emission of m/z 60 stopped when the larvae had pupated, which makes it an excellent indicator for actively feeding larvae. Methanethiol, DMS and DMDS levels increased much later in infested roots, indicating that activation of enzymes or genes involved in the production of these compounds may be required. Earlier studies have shown that both early and late responses can play a role in tritrophic interactions associated with Brassica species. Moreover, the identification of these root induced responses will help to design non-invasive analytical procedures to assess root infestations.
[Wieland2012] Wieland, F., A. N. Gloess, M. Keller, A. Wetzel, S. Schenker, and C. Yeretzian, "Online monitoring of coffee roasting by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS): towards a real-time process control for a consistent roast profile", Analytical and bioanalytical chemistry, vol. 402, no. 8: Springer, pp. 2531–2543, 2012.
Link: http://www.springerlink.com/index/E5415T1715865364.pdf
Abstract
A real-time automated process control tool for coffee roasting is presented to consistently and accurately achieve a targeted roast degree. It is based on the online monitoring of volatile organic compounds (VOC) in the off-gas of a drum roaster by proton transfer reaction time-of-flight mass spectrometry at a high time (1 Hz) and mass resolution (5,500 m/Δm at full width at half-maximum) and high sensitivity (better than parts per billion by volume). Forty-two roasting experiments were performed with the drum roaster being operated either on a low, medium or high hot-air inlet temperature (= energy input) and the coffee (Arabica from Antigua, Guatemala) being roasted to low, medium or dark roast degrees. A principal component analysis (PCA) discriminated, for each one of the three hot-air inlet temperatures, the roast degree with a resolution of better than ±1 Colorette. The 3D space of the three first principal components was defined based on 23 mass spectral profiles of VOCs and their roast degree at the end point of roasting. This provided a very detailed picture of the evolution of the roasting process and allowed establishment of a predictive model that projects the online-monitored VOC profile of the roaster off-gas in real time onto the PCA space defined by the calibration process and, ultimately, to control the coffee roasting process so as to achieve a target roast degree and a consistent roasting.
[Feilberg2012] Feilberg, A., D. Liu, C. Lunde Pedersen, and M. Jørgen Hansen, "Optimization of Biological Air Filters for Livestock Production Facilities", International conference on environmental odour monitoring and control, 2012.
Link: http://pure.au.dk/portal/en/activities/optimization-of-biological-air-filters-for-livestock-production-facilities(3a3304cb-6664-4fd6-810f-5a040cd26fe7).html
2011
[Kohl2011] Kohl, I., J. Herbig, J. Beauchamp, J. Dunkl, O. Tietje, and A. Hansel, "Online breath analysis of volatile organic compounds with PTR-MS: a guanidino breath marker for the status of uremia and kidney transplant rejection diagnosis.", 4th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 251, 2011.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_5.pdf
[DeGouw2011] De Gouw, JA., AM. Middlebrook, C. Warneke, R. Ahmadov, EL. Atlas, R. Bahreini, DR. Blake, CA. Brock, J. Brioude, DW. Fahey, et al., "Organic aerosol formation downwind from the Deepwater Horizon oil spill", Science, vol. 331, no. 6022: American Association for the Advancement of Science, pp. 1295–1299, 2011.
Link: http://www.sciencemag.org/content/331/6022/1295.short
Abstract
A large fraction of atmospheric aerosols are derived from organic compounds with various volatilities. A National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft made airborne measurements of the gaseous and aerosol composition of air over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico that occurred from April to August 2010. A narrow plume of hydrocarbons was observed downwind of DWH that is attributed to the evaporation of fresh oil on the sea surface. A much wider plume with high concentrations of organic aerosol (>25 micrograms per cubic meter) was attributed to the formation of secondary organic aerosol (SOA) from unmeasured, less volatile hydrocarbons that were emitted from a wider area around DWH. These observations provide direct and compelling evidence for the importance of formation of SOA from less volatile hydrocarbons.
[1508] Worton, D.. R., A.. H. Goldstein, D.. K. Farmer, K.. S. Docherty, J.. L. Jimenez, J.. B. Gilman, W.. C. Kuster, J.. de Gouw, B.. J. Williams, N.. M. Kreisberg, et al., "Origins and composition of fine atmospheric carbonaceous aerosol in the Sierra Nevada Mountains, California", Atmospheric Chemistry and Physics, vol. 11, pp. 10219–10241, Oct, 2011.
Link: http://nature.berkeley.edu/ahg/pubs/Worton et al acp-11-10219-2011.pdf
Abstract
<p>In this paper we report chemically resolved measurements of organic aerosol (OA) and related tracers during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) at the Blodgett Forest Research Station, California from 15 August&ndash;10 October 2007. OA contributed the majority of the mass to the fine atmospheric particles and was predominately oxygenated (OOA). The highest concentrations of OA were during sporadic wildfire influence when aged plumes were impacting the site. In situ measurements of particle phase molecular markers were dominated by secondary compounds and along with gas phase compounds could be categorized into six factors or sources: (1) aged biomass burning emissions and oxidized urban emissions, (2) oxidized urban emissions (3) oxidation products of monoterpene emissions, (4) monoterpene emissions, (5) anthropogenic emissions and (6) local methyl chavicol emissions and oxidation products. There were multiple biogenic components that contributed to OA at this site whose contributions varied diurnally, seasonally and in response to changing meteorological conditions, e.g. temperature and precipitation events. Concentrations of isoprene oxidation products were larger when temperatures were higher during the first half of the campaign (15 August&ndash;12 September) due to more substantial emissions of isoprene and enhanced photochemistry. The oxidation of methyl chavicol, an oxygenated terpene emitted by ponderosa pine trees, contributed similarly to OA throughout the campaign. In contrast, the abundances of monoterpene oxidation products in the particle phase were greater during the cooler conditions in the latter half of the campaign (13 September&ndash;10 October), even though emissions of the precursors were lower, although the mechanism is not known. OA was correlated with the anthropogenic tracers 2-propyl nitrate and carbon monoxide (CO), consistent with previous observations, while being comprised of mostly non-fossil carbon (&gt;75%). The correlation between OA and an anthropogenic tracer does not necessarily identify the source of the carbon as being anthropogenic but instead suggests a coupling between the anthropogenic and biogenic components in the air mass that might be related to the source of the oxidant and/or the aerosol sulfate. Observations of organosulfates of isoprene and α-pinene provided evidence for the likely importance of aerosol sulfate in spite of neutralized aerosol although acidic plumes might have played a role upwind of the site. This is in contrast to laboratory studies where strongly acidic seed aerosols were needed in order to form these compounds. These compounds together represented only a minor fraction (&lt;1%) of the total OA mass, which may be the result of the neutralized aerosol at the site or because only a small number of organosulfates were quantified. The low contribution of organosulfates to total OA suggests that other mechanisms, e.g. NOx enhancement of oxidant levels, are likely responsible for the majority of the anthropogenic enhancement of biogenic secondary organic aerosol observed at this site.</p>
2010
[Feilberg2010] Feilberg, A., D. Liu, A. P. S. Adamsen, M. J. Hansen, and K. E. N. Jonassen, "Odorant emissions from intensive pig production measured by online proton-transfer-reaction mass spectrometry.", Environ Sci Technol, vol. 44, no. 15: Department of Biosystems Engineering, Aarhus University, Blichers Alle 20, DK-8830 Tjele, Denmark. anders.feilberg@agrsci.dk, pp. 5894–5900, Aug, 2010.
Link: http://dx.doi.org/10.1021/es100483s
Abstract
Emission of odorous compounds from intensive livestock production is a cause of nuisance in populated rural areas. Knowledge on the chemical composition of odor and temporal variations in emissions are needed in order to identify factors of importance for emission rates and select proper abatement technologies. In this work, a method based on proton-transfer-reaction mass spectrometry (PTR-MS) has been developed and tested for continuous measurements of odorant emissions from intensive pig production facilities. The method is assessed to cover all presently known important odorants from this type of animal production with adequate sensitivity and a time resolution of less than one minute. The sensitivity toward hydrogen sulfide is demonstrated to exhibit a pronounced humidity dependency, which can be included in the calibration procedure in order to achieve quantitative results for this compound. Application of the method at an experimental pig facility demonstrated strong temporal variations in emissions, including diurnal variation. Based on these first results, air exchange and animal activity are suggested to be of importance for emission rates of odorants. Highest emissions are seen for hydrogen sulfide and acetic acid, whereas key odorants are evaluated from tabulated odor threshold values to be hydrogen sulfide, methanethiol, 4-methylphenol, and butanoic acid.
[Feilberg2010a] Feilberg, A., N. Dorno, and T. Nyord, "Odour emissions following land spreading of animal slurry assessed by proton-transfer-reaction mass spectrometry (PTR-MS)", Chemical Engineering Transactions, vol. 23, 2010.
Link: http://www.aidic.it/cet/10/23/019.pdf
[Sinha2010] Sinha, V., J. Williams, J. Lelieveld, TM. Ruuskanen, MK. Kajos, J. Patokoski, H. Hellen, H. Hakola, D. Mogensen, M. Boy, et al., "OH reactivity measurements within a boreal forest: evidence for unknown reactive emissions", Environmental science & technology, vol. 44, no. 17: ACS Publications, pp. 6614–6620, 2010.
Link: http://pubs.acs.org/doi/abs/10.1021/es101780b
Abstract
Boreal forests emit large amounts of volatile organic compounds (VOCs) which react with the hydroxyl radical (OH) to influence regional ozone levels and form secondary organic aerosol. Using OH reactivity measurements within a boreal forest in Finland, we investigated the budget of reactive VOCs. OH reactivity was measured using the comparative reactivity method, whereas 30 individual VOCs were measured using proton transfer reaction mass spectrometry, thermal-desorption gas chromatography mass spectrometry, and liquid chromatography mass spectrometry, in August 2008. The measured OH reactivity ranged from below detection limit (3.5 s−1), to 60 s−1 in a single pollution event. The average OH reactivity was 9 s−1 and no diel variation was observed in the profiles. The measured OH sinks (30 species) accounted for only 50% of the total measured OH reactivity, implying unknown reactive VOCs within the forest. The five highest measured OH sinks were: monoterpenes (1 s−1), CO (0.7 s−1), isoprene (0.5 s−1), propanal and acetone (0.3 s−1), and methane (0.3 s−1). We suggest that models be constrained by direct OH reactivity measurements to accurately assess the impact of boreal forest emissions on regional atmospheric chemistry and climate.
2009
[Dunne2009] Dunne, E., I. Galbally, S. Lawson, and T. Patti, "Observations of fragmentation of simple organic compounds in proton transfer mass spectrometry measurements", CONFERENCE SERIES, pp. 214, 2009.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_4.pdf
[Biasioli2009] Biasioli, F., E. Aprea, G. Odorizzi, F. Gasperi, and T. D. Maerk, "Odour monitoring in composting plants by PTR-MS and PTR-TOF-MS", CONFERENCE SERIES, pp. 191, 2009.
Link: http://www.ionicon.com/downloads/contributions_4th-PTR-MS_conference.pdf#page=191
[Herbig2009a] Herbig, J., M. Müller, S. Schallhart, T. Titzmann, M. Graus, and A. Hansel, "On-line breath analysis with PTR-TOF.", J Breath Res, vol. 3, no. 2: Ionimed Analytik GmbH, Innsbruck, Austria., pp. 027004, Jun, 2009.
Link: http://dx.doi.org/10.1088/1752-7155/3/2/027004
Abstract
We report on on-line breath gas analysis with a new type of analytical instrument, which represents the next generation of proton-transfer-reaction mass spectrometers. This time-of-flight mass spectrometer in combination with the soft proton-transfer-reaction ionization (PTR-TOF) offers numerous advantages for the sensitive detection of volatile organic compounds and overcomes several limitations. First, a time-of-flight instrument allows for a measurement of a complete mass spectrum within a fraction of a second. Second, a high mass resolving power enables the separation of isobaric molecules and the identification of their chemical composition. We present the first on-line breath measurements with a PTR-TOF and demonstrate the advantages for on-line breath analysis. In combination with buffered end-tidal (BET) sampling, we obtain a complete mass spectrum up to 320 Th within one exhalation with a signal-to-noise ratio sufficient to measure down to pptv levels. We exploit the high mass resolving power to identify the main components in the breath composition of several healthy volunteers.
[Herbig2009] Herbig, J., M. Seger, I. Kohl, G. Mayramhof, T. Titzmann, A. Preinfalk, K. Winkler, J. Dunkl, B. Pfeifer, C. Baumgartner, et al., "Online breath sampling with PTR-MS - A setup for large screening studies", 4th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 46, 2009.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_4.pdf
[1441] Jordan, A., S.. Haidacher, G.. Hanel, E.. Hartungen, J. Herbig, L.. Märk, R.. Schottkowsky, H.. Seehauser, P.. Sulzer, and T.D.. Märk, "An online ultra-high sensitivity Proton-transfer-reaction mass-spectrometer combined with switchable reagent ion capability (PTR + SRI−MS)", International Journal of Mass Spectrometry, vol. 286, pp. 32 - 38, 2009.
Link: http://www.sciencedirect.com/science/article/pii/S1387380609002036
Abstract
<div>Proton-transfer-reaction mass-spectrometry (PTR-MS) developed in the</div> <div>1990s is used today in a wide range of scientific and technical fields.</div> <div>PTR-MS allows for real-time, online determination of absolute concentrations</div> <div>of volatile (organic) compounds (VOCs) in air with high sensitivity</div> <div>(into the low pptv range) and a fast response time (in the 40&ndash;100 ms</div> <div>time regime). Most PTR-MS instruments employed so far use an ion</div> <div>source consisting of a hollow cathode (HC) discharge in water vapour</div> <div>which provides an intense source of proton donor H3O+ ions. As the</div> <div>use of other ions, e.g. NO+ and O2+, can be useful for the identification</div> <div>of \{VOCs\} and for the detection of \{VOCs\} with proton affinities</div> <div>(PA) below that of H2O, selected ion flow tube mass spectrometry</div> <div>(SIFT-MS) with mass selected ions has been applied in these instances.</div> <div>SIFT-MS suffers, however, from at least two orders lower reagent</div> <div>ion counts rates and therefore SIFT-MS suffers from lower sensitivity</div> <div>than PTR-MS. Here we report the development of a PTR-MS instrument</div> <div>using a modified \{HC\} ion source and drift tube design, which allows</div> <div>for the easy and fast switching between H3O+, NO+ and O2+ ions produced</div> <div>in high purity and in large quantities in this source. This instrument</div> <div>is capable of measuring low concentrations (with detection limits</div> <div>approaching the ppqv regime) of \{VOCs\} using any of the three reagent</div> <div>ions investigated in this study. Therefore this instrument combines</div> <div>the advantages of the PTR-MS technology (the superior sensitivity)</div> <div>with those of SIFT-MS (detection of \{VOCs\} with \{PAs\} smaller</div> <div>than that of the water molecule and the capability to distinguish</div> <div>between isomeric compounds). We will first discuss the setup of this</div> <div>new PTR+SRI-MS mass spectrometer instrument, its performance for</div> <div>aromates, aldehydes and ketones (with a sensitivity of up to nearly</div> <div>1000 cps/ppbv and a detection limit of about several 100&amp;#xa0;ppqv)</div> <div>and finally give some examples concerning the ability to distinguish</div> <div>structural isomeric compounds.&nbsp;</div>

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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.
Link

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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