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Found 52 results
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2003
[Guazzotti2003] Guazzotti, SA., DT. Suess, KR. Coffee, PK. Quinn, TS. Bates, A. Wisthaler, A. Hansel, WP. Ball, RR. Dickerson, C. Neusüß, et al., "Characterization of carbonaceous aerosols outflow from India and Arabia: Biomass/biofuel burning and fossil fuel combustion", Journal of geophysical research, vol. 108, no. D15: American Geophysical Union, pp. 4485, 2003.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2002JD003277/abstract
Abstract
A major objective of the Indian Ocean Experiment (INDOEX) involves the characterization of the extent and chemical composition of pollution outflow from the Indian Subcontinent during the winter monsoon. During this season, low-level flow from the continent transports pollutants over the Indian Ocean toward the Intertropical Convergence Zone (ITCZ). Traditional standardized aerosol particle chemical analysis, together with real-time single particle and fast-response gas-phase measurements provided characterization of the sampled aerosol chemical properties. The gas- and particle-phase chemical compositions of encountered air parcels changed according to their geographic origin, which was traced by back trajectory analysis. The temporal evolutions of acetonitrile, a long-lived specific tracer for biomass/biofuel burning, number concentration of submicrometer carbon-containing particles with potassium (indicative of combustion sources), and mass concentration of submicrometer non-sea-salt (nss) potassium are compared. High correlation coefficients (0.84 < r2 < 0.92) are determined for these comparisons indicating that most likely the majority of the species evolve from the same, related, or proximate sources. Aerosol and trace gas measurements provide evidence that emissions from fossil fuel and biomass/biofuel burning are subject to long-range transport, thereby contributing to anthropogenic pollution even in areas downwind of South Asia. Specifically, high concentrations of submicrometer nss potassium, carbon-containing particles with potassium, and acetonitrile are observed in air masses advected from the Indian subcontinent, indicating a strong impact of biomass/biofuel burning in India during the sampling periods (74 (±9)% biomass/biofuel contribution to submicrometer carbonaceous aerosol). In contrast, lower values for these same species were measured in air masses from the Arabian Peninsula, where dominance of fossil fuel combustion is suggested by results from single-particle analysis and supported by results from gas-phase measurements (63 (±9))% fossil fuel contribution to submicrometer carbonaceous aerosol). Results presented here demonstrate the importance of simultaneous, detailed gas- and particle-phase measurements of related species when evaluating possible source contributions to aerosols in different regions of the world.
[Roberts2003] Roberts, D. D., P. Pollien, N. Antille, C. Lindinger, and C. Yeretzian, "Comparison of nosespace, headspace, and sensory intensity ratings for the evaluation of flavor absorption by fat.", J Agric Food Chem, vol. 51, no. 12: Nestlé Research Center, P.O. Box 44, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland. dahlroberts@yahoo.com, pp. 3636–3642, Jun, 2003.
Link: http://dx.doi.org/10.1021/jf026230+
Abstract
The goal of this study was to better understand the correspondence between sensory perception and in-nose compound concentration. Five aroma compounds at three different concentrations increasing by factors of 4 were added to four matrixes (water, skim milk, 2.7% fat milk, and 3.8% fat milk). These were evaluated by nosespace analysis with detection by proton transfer reaction mass spectrometry (PTR-MS), using five panelists. These same panelists evaluated the perceived intensity of each compound in the matrixes at the three concentrations. PTR-MS quantification found that the percent released from an aqueous solution swallowed immediately was between 0.1 and 0.6%, depending on the compound. The nosespace and sensory results showed the expected effect of fat on release, where lipophilic compounds showed reductions in release as fat content increases. The effect is less than that observed in headspace studies. A general correlation between nosespace concentration and sensory intensity ratings was found. However, examples of perceptual masking were found where higher fat milks showed reductions in aroma compound intensity ratings, even if the nosespace concentrations were the same.
[Christian2003] Christian, TJ., B. Kleiss, RJ. Yokelson, R. Holzinger, PJ. Crutzen, WM. Hao, BH. Saharjo, and DE. Ward, "Comprehensive laboratory measurements of biomass-burning emissions: 1. Emissions from Indonesian, African, and other fuels", J. Geophys. Res, vol. 108, no. 4719, pp. 1–4719, 2003.
Link: http://www.agu.org/pubs/crossref/2003/2003JD003704.shtml
Abstract
Trace gas and particle emissions were measured from 47 laboratory fires burning 16 regionally to globally significant fuel types. Instrumentation included the following: open-path Fourier transform infrared spectroscopy; proton transfer reaction mass spectrometry; filter sampling with subsequent analysis of particles with diameter <2.5 μm for organic and elemental carbon and other elements; and canister sampling with subsequent analysis by gas chromatography (GC)/flame ionization detector, GC/electron capture detector, and GC/mass spectrometry. The emissions of 26 compounds are reported by fuel type. The results include the first detailed measurements of the emissions from Indonesian fuels. Carbon dioxide, CO, CH4, NH3, HCN, methanol, and acetic acid were the seven most abundant emissions (in order) from burning Indonesian peat. Acetol (hydroxyacetone) was a major, previously unobserved emission from burning rice straw (21–34 g/kg). The emission factors for our simulated African fires are consistent with field data for African fires for compounds measured in both the laboratory and the field. However, the higher concentrations and more extensive instrumentation in this work allowed quantification of at least 10 species not previously quantified for African field fires (in order of abundance): acetaldehyde, phenol, acetol, glycolaldehyde, methylvinylether, furan, acetone, acetonitrile, propenenitrile, and propanenitrile. Most of these new compounds are oxygenated organic compounds, which further reinforces the importance of these reactive compounds as initial emissions from global biomass burning. A few high-combustion-efficiency fires emitted very high levels of elemental (black) carbon, suggesting that biomass burning may produce more elemental carbon than previously estimated.
[Biasioli2003] Biasioli, F., F. Gasperi, E. Aprea, D. Mott, E. Boscaini, D. Mayr, and T. D. Maerk, "Coupling proton transfer reaction-mass spectrometry with linear discriminant analysis: a case study.", J Agric Food Chem, vol. 51, no. 25: Istituto Agrario di S. Michele a/A, S. Michele, Via E. Mach 2, 38010, Italy. franco.biasioli@ismaa.it, pp. 7227–7233, Dec, 2003.
Link: http://dx.doi.org/10.1021/jf030248i
Abstract
Proton transfer reaction-mass spectrometry (PTR-MS) measurements on single intact strawberry fruits were combined with an appropriate data analysis based on compression of spectrometric data followed by class modeling. In a first experiment 8 of 9 different strawberry varieties measured on the third to fourth day after harvest could be successfully distinguished by linear discriminant analysis (LDA) on PTR-MS spectra compressed by discriminant partial least squares (dPLS). In a second experiment two varieties were investigated as to whether different growing conditions (open field, tunnel), location, and/or harvesting time can affect the proposed classification method. Internal cross-validation gives 27 successes of 28 tests for the 9 varieties experiment and 100% for the 2 clones experiment (30 samples). For one clone, present in both experiments, the models developed for one experiment were successfully tested with the homogeneous independent data of the other with success rates of 100% (3 of 3) and 93% (14 of 15), respectively. This is an indication that the proposed combination of PTR-MS with discriminant analysis and class modeling provides a new and valuable tool for product classification in agroindustrial applications.
2004
[Cooper2004] Cooper, OR., C. Forster, D. Parrish, M. Trainer, E. Dunlea, T. Ryerson, G. Huebler, F. Fehsenfeld, D. Nicks, J. Holloway, et al., "A case study of transpacific warm conveyor belt transport: Influence of merging airstreams on trace gas import to North America", Journal of geophysical research, vol. 109, no. D23: American Geophysical Union, pp. D23S08, 2004.
Link: http://www.agu.org/pubs/crossref/2004/2003JD003624.shtml
Abstract
The warm conveyor belt (WCB), the major cloud-forming airstream of midlatitude cyclones, is the primary mechanism for rapidly transporting air pollution from one continent to another. However, relatively little has been written on WCB transport across the North Pacific Ocean. To address this important intercontinental transport route, this study describes the life cycle of a WCB associated with the export of a highly polluted air mass from Asia to North America. This event was sampled using in situ measurements from an aircraft platform flying above the North American West Coast during the 2002 Intercontinental Transport and Chemical Transformation (ITCT 2K2) experiment on 5 May. Satellite imagery, trajectory ensembles, in situ measurements, and animations are used to illustrate the formation of the WCB near eastern Asia, its entrainment of polluted air masses, its transport path across the Pacific, and its decay above the eastern North Pacific Ocean and western North America. A major finding is that a WCB can entrain air from a variety of source regions and not just the atmospheric boundary layer. We estimate that 8% of the WCB's mass originated in the stratosphere and 44% passed through the lower troposphere, of which two thirds passed through the lower troposphere above the populated regions of eastern Asia. The remaining 48% traveled entirely within the middle and upper troposphere over the previous 5.5 days. Interestingly, an estimated 18% of the WCB's mass was entrained from an upwind and decaying WCB via a newly discovered but apparently common transport mechanism. Only 9% of the WCB's mass subsequently passed through the lower troposphere of the United States, with the remainder passing over North America in the middle and upper troposphere.
[Biasioli2004b] Biasioli, F., F. Gasperi, D. Mott, E. Aprea, F. Marini, and TD. Maerk, "Characterization of Strawberry Genotypes by PTR-MS Spectral Fingerprinting: a Three Year Study", V International Strawberry Symposium 708, pp. 497–500, 2004.
Link: http://www.actahort.org/books/708/708_87.htm
Abstract
Proton Transfer Reaction Mass Spectrometry (PTR-MS) fingerprinting has been used to accurately and rapidly identify the cultivar of single intact strawberry fruits. The technique has been applied in a 3-cultivar experiment with 70 fruits harvested in 2002, 2003 and 2004. The proposed models correctly predicted the cultivar. Cross-validation tests verified 100% correct classification. The data indicated the possibility of correctly characterizing single fruit by fast non-invasive measurements without any pre-treatment and/or concentration of the headspace gas mixture. This is a necessary preliminary step in view of correlation studies of PTR-MS data with genetics and other characterization of fruits, in particular, sensory analysis. Extension to more cultivars is envisaged.
[Boscaini2004] Boscaini, E., T. Mikoviny, A. Wisthaler, E. von Hartungen, and T. D. Märk, "Characterization of wine with PTR-MS", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 215–219, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003537
Abstract
A new method for measuring volatile profiles of alcoholic beverages (or other ethanol-containing analytes such as perfumes or herbs) has been developed. The method is based on proton transfer reaction mass spectrometry (PTR-MS). However, instead of hydronium ions (H3O+) protonated ethanol clusters (C2H5OH2+(C2H5OH)n = 1,2) are used as chemical ionization reagent ions. A stable reagent ion distribution is obtained by a 10-fold dilution of analyte headspace into ethanol-saturated nitrogen. Samples with different ethanol content can thus be directly compared. Characteristic mass spectral fingerprints have been obtained for four wine varieties. Principal component analysis discriminates between different wine varieties and shows specific correlations between wine variety and selected ions.
[Christian2004] Christian, TJ., B. Kleiss, RJ. Yokelson, R. Holzinger, PJ. Crutzen, WM. Hao, T. Shirai, and DR. Blake, "Comprehensive laboratory measurements of biomass-burning emissions: 2. First intercomparison of open-path FTIR, PTR-MS, and GC-MS/FID/ECD", Journal of geophysical research, vol. 109, no. D2: American Geophysical Union, pp. D02311, 2004.
Link: http://www.agu.org/pubs/crossref/2004/2003JD003874.shtml
Abstract
Oxygenated volatile organic compounds (OVOC) can dominate atmospheric organic chemistry, but they are difficult to measure reliably at low levels in complex mixtures. Several techniques that have been used to speciate nonmethane organic compounds (NMOC) including OVOC were codeployed/intercompared in well-mixed smoke generated by 47 fires in the U.S. Department of Agriculture Forest Service Fire Sciences Combustion Facility. The agreement between proton transfer reaction mass spectrometry (PTR-MS) and open-path Fourier transform infrared spectroscopy (OP-FTIR) was excellent for methanol (PT/FT = 1.04 ± 0.118) and good on average for phenol (0.843 ± 0.845) and acetol (∼0.81). The sum of OP-FTIR mixing ratios for acetic acid and glycolaldehyde agreed (within experimental uncertainty) with the PTR-MS mixing ratios for protonated mass 61 (PT/FT = 1.17 ± 0.34), and the sum of OP-FTIR mixing ratios for furan and isoprene agreed with the PTR-MS mixing ratios for protonated mass 69 (PT/FT = 0.783 ± 0.465). The sum of OP-FTIR mixing ratios for acetone and methylvinylether accounted for most of the PTR-MS protonated mass 59 signal (PT/FT = 1.29 ± 0.81), suggesting that one of these compounds was underestimated by OP-FTIR or that it failed to detect other compounds that could contribute at mass 59. Canister grab sampling followed by gas chromatography (GC) with mass spectrometry (MS), flame ionization detection (FID), and electron capture detection (ECD) analysis by two different groups agreed well with OP-FTIR for ethylene, acetylene, and propylene. However, these propylene levels were below those observed by PTR-MS (PT/FT = 2.33 ± 0.89). Good average agreement between PTR-MS and GC was obtained for benzene and toluene. At mixing ratios above a few parts per billion the OP-FTIR had advantages for measuring sticky compounds (e.g., ammonia and formic acid) or compounds with low proton affinity (e.g., hydrogen cyanide and formaldehyde). Even at these levels, only the PTR-MS measured acetonitrile and acetaldehyde. Below a few ppbv only the PTR-MS measured a variety of OVOC, but the possibility of fragmentation, interference, and sampling losses must be considered.
[Schnitzler2004] SCHNITZLER, JÖRG-PETER., M. Graus, J. Kreuzwieser, U. Heizmann, H. Rennenberg, A. Wisthaler, and A. Hansel, "Contribution of different carbon sources to isoprene biosynthesis in poplar leaves", Plant Physiology, vol. 135, no. 1: Am Soc Plant Biol, pp. 152–160, 2004.
Link: http://www.plantphysiol.org/content/135/1/152.short
Abstract
This study was performed to test if alternative carbon sources besides recently photosynthetically fixed CO2 are used for isoprene formation in the leaves of young poplar (Populus × canescens) trees. In a 13CO2 atmosphere under steady state conditions, only about 75% of isoprene became 13C labeled within minutes. A considerable part of the unlabeled carbon may be derived from xylem transported carbohydrates, as may be shown by feeding leaves with [U-13C]Glc. As a consequence of this treatment approximately 8% to 10% of the carbon emitted as isoprene was 13C labeled. In order to identify further carbon sources, poplar leaves were depleted of leaf internal carbon pools and the carbon pools were refilled with 13C labeled carbon by exposure to 13CO2. Results from this treatment showed that about 30% of isoprene carbon became 13C labeled, clearly suggesting that, in addition to xylem transported carbon and CO2, leaf internal carbon pools, e.g. starch, are used for isoprene formation. This use was even increased when net assimilation was reduced, for example by abscisic acid application. The data provide clear evidence of a dynamic exchange of carbon between different cellular precursors for isoprene biosynthesis, and an increasing importance of these alternative carbon pools under conditions of limited photosynthesis. Feeding [1,2-13C]Glc and [3-13C]Glc to leaves via the xylem suggested that alternative carbon sources are probably derived from cytosolic pyruvate/phosphoenolpyruvate equivalents and incorporated into isoprene according to the predicted cleavage of the 3-C position of pyruvate during the initial step of the plastidic deoxyxylulose-5-phosphate pathway.
2005
[Penuelas2005] Penuelas, J., I. Filella, C. Stefanescu, and J. Llusià, "Caterpillars of Euphydryas aurinia (Lepidoptera: Nymphalidae) feeding on Succisa pratensis leaves induce large foliar emissions of methanol.", New Phytol, vol. 167, no. 3: Unitat Ecofisiologia CSIC-CREAF CREAF, Edifici C, Universitat Autónoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain. josep.penuelas@uab.es, pp. 851–857, Sep, 2005.
Link: http://dx.doi.org/10.1111/j.1469-8137.2005.01459.x
Abstract
A major new discovery made in the last decade is that plants commonly emit large amounts and varieties of volatiles after damage inflicted by herbivores, and not merely from the site of injury. However, analytical methods for measuring herbivore-induced volatiles do not usually monitor the whole range of these compounds and are complicated by the transient nature of their formation and by their chemical instability. Here we present the results of using a fast and highly sensitive proton transfer reaction-mass spectrometry (PTR-MS) technique that allows simultaneous on-line monitoring of leaf volatiles in the pptv (pmol mol(-1)) range. The resulting on-line mass scans revealed that Euphydryas aurinia caterpillars feeding on Succisa pratensis leaves induced emissions of huge amounts of methanol–a biogeochemically active compound and a significant component of the volatile organic carbon found in the atmosphere–and other immediate, late and systemic volatile blends (including monoterpenes, sesquiterpenes and lipoxygenase-derived volatile compounds). In addition to influencing neighboring plants, as well as herbivores and their predators and parasitoids, these large emissions might affect atmospheric chemistry and physics if they are found to be generalized in other plant species.
[Herndon2005] Herndon, S. C., J. T. Jayne, M. S. Zahniser, D. R. Worsnop, B. Knighton, E. Alwine, B. K. Lamb, M. Zavala, D. D. Nelson, B. J McManus, et al., "Characterization of urban pollutant emission fluxes and ambient concentration distributions using a mobile laboratory with rapid response instrumentation", Faraday Discussions, vol. 130: Royal Society of Chemistry, pp. 327–339, 2005.
Link: http://pubs.rsc.org/en/content/articlehtml/2005/fd/b500411j
Abstract
A large and increasing fraction of the planet’s population lives in megacities, especially in the developing world. These large metropolitan areas generally have very high levels of both gaseous and particulate air pollutants that have severe impacts on human health, ecosystem viability, and climate on local, regional, and even continental scales. Emissions fluxes and ambient pollutant concentration distributions are generally poorly characterized for large urban areas even in developed nations. Much less is known about pollutant sources and concentration patterns in the faster growing megacities of the developing world. New methods of locating and measuring pollutant emission sources and tracking subsequent atmospheric chemical transformations and distributions are required. Measurement modes utilizing an innovative van based mobile laboratory equipped with a suite of fast response instruments to characterize the complex and “nastier” chemistry of the urban boundary layer are described. Instrumentation and measurement strategies are illustrated with examples from the Mexico City and Boston metropolitan areas. It is shown that fleet average exhaust emission ratios of formaldehyde (HCHO), acetaldehyde (CH3CHO) and benzene (C6H6) are substantial in Mexico City, with gasoline powered vehicles emitting higher levels normalized by fuel consumption. NH3 exhaust emissions from newer light duty vehicles in Mexico City exceed levels from similar traffic in Boston. A mobile conditional sampling air sample collection mode designed to collect samples from intercepted emission plumes for later analysis is also described.
[Lee2005] Lee, A., GW. Schade, R. Holzinger, and AH. Goldstein, "A comparison of new measurements of total monoterpene flux with improved measurements of speciated monoterpene flux", Atmospheric Chemistry and Physics, vol. 5, no. 2: Copernicus GmbH, pp. 505–513, 2005.
Link: http://www.atmos-chem-phys.net/5/505/2005/acp-5-505-2005.pdf
2006
[vonDahl2006] von Dahl}, C. C. {, M. Haevecker, R. Schloegl, and I. T. Baldwin, "Caterpillar-elicited methanol emission: a new signal in plant-herbivore interactions?", Plant J, vol. 46, no. 6: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Strasse 8, 07745 Jena, Germany., pp. 948–960, Jun, 2006.
Link: http://dx.doi.org/10.1111/j.1365-313X.2006.02760.x
Abstract
Plants release into the atmosphere large quantities of volatile organic compounds (VOCs), of which methanol (MeOH), a putative waste product, is the second most abundant. Using online proton-transfer-reaction mass spectrometry (PTR-MS), we demonstrate that when Manduca sexta larvae attack Nicotiana attenuata plants, the wound-induced release of MeOH dramatically increases. The sustained MeOH emission 24 h after herbivore feeding is already substantially greater than the release of the well-characterized green-leaf VOC E-2-hexenal. Herbivore attack and treatment of puncture wounds with larval oral secretions (OS) increased the transcript accumulation and activity of leaf pectin methylesterases (PMEs), and decreased the degree of pectin methylation, as determined by (1)H-NMR; therefore, we propose that the released MeOH originates from the activation of PMEs by herbivore attack. The herbivore- and OS-elicited MeOH results not from the activity of previously characterized elicitors in OS but from a pH shift at the wound site when larval OS (pH 8.5-9.5) are introduced into the wounds during feeding. Applying MeOH to plants in quantities that mimic the herbivory-elicited release decreases the activity of the potent plant defense proteins trypsin proteinase inhibitors (TPI), and increases the performance of the attacking larvae. The pH of lepidopteran larvae regurgitants is commonly very high, and the MeOH released during feeding that is elicited by the pH change at the wound site functions as a quantitative signal that influences the outcome of the plant-herbivore interaction.
[Zavala2006] Zavala, M., SC. Herndon, RS. Slott, EJ. Dunlea, LC. Marr, JH. Shorter, M. Zahniser, WB. Knighton, TM. Rogers, CE. Kolb, et al., "Characterization of on-road vehicle emissions in the Mexico City Metropolitan Area using a mobile laboratory in chase and fleet average measurement modes during the MCMA-2003 field campaign", Atmospheric Chemistry and Physics, vol. 6, no. 12: Copernicus GmbH, pp. 5129–5142, 2006.
Link: http://www.atmos-chem-phys.net/6/5129/2006/acp-6-5129-2006.html
Abstract
A mobile laboratory was used to measure on-road vehicle emission ratios during the MCMA-2003 field campaign held during the spring of 2003 in the Mexico City Metropolitan Area (MCMA). The measured emission ratios represent a sample of emissions of in-use vehicles under real world driving conditions for the MCMA. From the relative amounts of NOx and selected VOC's sampled, the results indicate that the technique is capable of differentiating among vehicle categories and fuel type in real world driving conditions. Emission ratios for NOx, NOy, NH3, H2CO, CH3CHO, and other selected volatile organic compounds (VOCs) are presented for chase sampled vehicles in the form of frequency distributions as well as estimates for the fleet averaged emissions. Our measurements of emission ratios for both CNG and gasoline powered "colectivos" (public transportation buses that are intensively used in the MCMA) indicate that – in a mole per mole basis – have significantly larger NOx and aldehydes emissions ratios as compared to other sampled vehicles in the MCMA. Similarly, ratios of selected VOCs and NOy showed a strong dependence on traffic mode. These results are compared with the vehicle emissions inventory for the MCMA, other vehicle emissions measurements in the MCMA, and measurements of on-road emissions in U.S. cities. We estimate NOx emissions as 100 600±29 200 metric tons per year for light duty gasoline vehicles in the MCMA for 2003. According to these results, annual NOx emissions estimated in the emissions inventory for this category are within the range of our estimated NOx annual emissions. Our estimates for motor vehicle emissions of benzene, toluene, formaldehyde, and acetaldehyde in the MCMA indicate these species are present in concentrations higher than previously reported. The high motor vehicle aldehyde emissions may have an impact on the photochemistry of urban areas.
[Ng2006] Ng, N. L., J. H. Kroll, M. D. Keywood, R. Bahreini, V. Varutbangkul, R. C. Flagan, J. H. Seinfeld, A. Lee, and A. H. Goldstein, "Contribution of first- versus second-generation products to secondary organic aerosols formed in the oxidation of biogenic hydrocarbons.", Environ Sci Technol, vol. 40, no. 7: Department of Environmental Science, California Institute of Technology, Pasadena, California 91125, USA., pp. 2283–2297, Apr, 2006.
Link: http://pubs.acs.org/doi/abs/10.1021/es052269u
Abstract
Biogenic hydrocarbons emitted by vegetation are important contributors to secondary organic aerosol (SOA), but the aerosol formation mechanisms are incompletely understood. In this study, the formation of aerosols and gas-phase products from the ozonolysis and photooxidation of a series of biogenic hydrocarbons (isoprene, 8 monoterpenes, 4 sesquiterpenes, and 3 oxygenated terpenes) are examined. By comparing aerosol growth (measured by Differential Mobility Analyzers, DMAs) and gas-phase concentrations (monitored by a Proton Transfer Reaction Mass Spectrometer, PTR-MS), we study the general mechanisms of SOA formation. Aerosol growth data are presented in terms of a "growth curve", a plot of aerosol mass formed versus the amount of hydrocarbon reacted. From the shapes of the growth curves, it is found that all the hydrocarbons studied can be classified into two groups based entirely on the number of double bonds of the hydrocarbon, regardless of the reaction systems (ozonolysis or photooxidation) and the types of hydrocarbons studied: compounds with only one double bond and compounds with more than one double bond. For compounds with only one double bond, the first oxidation step is rate-limiting, and aerosols are formed mainly from low volatility first-generation oxidation products; whereas for compounds with more than one double bond, the second oxidation step may also be rate-limiting and second-generation products contribute substantially to SOA growth. This behavior is characterized by a vertical section in the growth curve, in which continued aerosol growth is observed even after all the parent hydrocarbon is consumed.
[Biasioli2006] Biasioli, F., F. Gasperi, E. Aprea, I. Endrizzi, V. Framondino, F. Marini, D. Mott, and T. D. Maerk, "Correlation of PTR-MS spectral fingerprints with sensory characterisation of flavour and odour profile of "Trentingrana" cheese", Food quality and preference, vol. 17, no. 1: Elsevier, pp. 63–75, 2006.
Link: http://www.sciencedirect.com/science/article/pii/S095032930500090X
Abstract
Proton transfer reaction-mass spectrometry (PTR-MS) is a relatively new technique that allows the fast and accurate detection of volatile organic compounds. The paper discusses the possibility of correlating the PTR-MS spectral fingerprint of the mixture of volatile compounds present in the head-space of 20 samples of “Trentingrana”, the variety of Grana Padano produced in Trentino (Northern Italy), with the sensory evaluation (Quantitative Descriptive Analysis) of the same samples obtained by a panel of trained judges. Only attributes related to odours (six attributes) and flavours (six attributes) are considered. Results of descriptive statistics are shown and the performances of different multivariate calibration methods (Partial Least Squares, both PLS1 and PLS2) are compared by evaluating the errors in the cross-validated estimation of the sensory attributes. PLS2 seems to give a good average description providing an overall insight of the problem but does not provide an accurate prediction of the individual sensory attributes. PLS1 analysis is more accurate and performs well in most cases but it uses several latent variables, so that the interpretation of the loadings is not straightforward. The preliminary application of Orthogonal Signal Correction filtering on PTR-MS spectra followed by PLS1 analysis results in a good estimation for most of the attributes and has the advantage to use only one or two latent variables. Comparison with other works and a tentative indication of the compounds correlated with sensory description are reported.
2007
[Yelvington2007] Yelvington, P. E., S. C. Herndon, J. C. Wormhoudt, J. T. Jayne, R. C. Miake-Lye, B. W Knighton, and C. Wey, "Chemical speciation of hydrocarbon emissions from a commercial aircraft engine", Journal of Propulsion and Power, vol. 23, no. 5, pp. 912–918, 2007.
Link: http://arc.aiaa.org/doi/abs/10.2514/1.23520
2008
[Karl2008] Karl, T., A. Guenther, A. Turnipseed, EG. Patton, K. Jardine, and , "Chemical sensing of plant stress at the ecosystem scale", Biogeosciences Discussions, vol. 5, no. 3, pp. 2381–2399, 2008.
Link: http://hal.archives-ouvertes.fr/hal-00298013/
Abstract
Significant ecosystem-scale emissions of methylsalicylate (MeSA), a semivolatile plant hormone thought to act as the mobile signal for systemic acquired resistance (SAR) (Park et al., 2006), were observed in an agroforest. Our measurements show that plant internal defence mechanisms can be activated in response to temperature stress and are modulated by water availability on large scales. Highest MeSA fluxes (up to 0.25 mg/m2/h) were observed after plants experienced ambient night-time temperatures of  7.5°C followed by a large daytime temperature increase (e.g. up to 22°C). Under these conditions estimated night-time leaf temperatures were as low as  4.6°C, likely inducing a response to prevent chilling injury (Ding et al., 2002). Our observations imply that plant hormones can be a significant component of ecosystem scale volatile organic compound (VOC) fluxes (e.g. as high as the total monoterpene (MT) flux) and therefore contribute to the missing VOC budget (de Carlo et al., 2004; Goldstein and Galbally, 2007). If generalized to other ecosystems and different types of stresses these findings suggest that semivolatile plant hormones have been overlooked by investigations of the impact of biogenic VOCs on aerosol formation events in forested regions (Kulmala et al., 2001; Boy et al., 2000). Our observations show that the presence of MeSA in canopy air serves as an early chemical warning signal indicating ecosystem-scale stresses before visible damage becomes apparent. As a chemical metric, ecosystem emission measurements of MeSA in ambient air could therefore support field studies investigating factors that adversely affect plant growth.
[Sinha2008] Sinha, V., J. Williams, JN. Crowley, and J. Lelieveld, "The Comparative Reactivity Method–a new tool to measure total OH Reactivity in ambient air", Atmospheric Chemistry and Physics, vol. 8, no. 8: Copernicus GmbH, pp. 2213–2227, 2008.
Link: http://www.atmos-chem-phys.net/8/2213/2008/acp-8-2213-2008.pdf
[Kushch2008] Kushch, I., K. Schwarz, L. Schwentner, B. Baumann, A. Dzien, A. Schmid, K. Unterkofler, G. Gastl, P. Span?l, D. Smith, et al., "Compounds enhanced in a mass spectrometric profile of smokers' exhaled breath versus non-smokers as determined in a pilot study using PTR-MS.", J Breath Res, vol. 2, no. 2: Department of Anaesthesiology and Critical Care Medicine, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria. Breath Research Unit of the Austrian Academy of Sciences, Dammstrasse 22, A-6850 Dornbirn, Austria., pp. 026002, Jun, 2008.
Link: http://dx.doi.org/10.1088/1752-7155/2/2/026002
Abstract
{A pilot study has been carried out to define typical characteristics of the trace gas compounds in exhaled breath of non-smokers and smokers to assist interpretation of breath analysis data from patients who smoke with respiratory diseases and lung cancer. Exhaled breath was analyzed using proton transfer reaction-mass spectrometry (PTR-MS) for 370 volunteers (81 smokers, 210 non-smokers, 79 ex-smokers). Volatile organic compounds corresponding to product ions at seven mass-to-charge ratios (m/z 28, 42, 69, 79, 93, 97, 123) in the PTR-MS spectra differentiated between smokers and non-smokers. The Youden index (= maximum of sensitivity + specificity - 1, YI) as a measure for differentiation between smokers and non-smokers was YI = 0.43 for ions at the m/z values 28 (tentatively identified as HCN)
[Davison2008] Davison, B.., A.. Brunner, C.. Ammann, C.. Spirig, M.. Jocher, and A.. Neftel, "Cut-induced VOC emissions from agricultural grasslands.", Plant Biol (Stuttg), vol. 10, no. 1: Department of Environmental Sciences, Lancaster University, Lancaster LA1 4YQ, UK. b.davison@lancaster.ac.uk, pp. 76–85, Jan, 2008.
Link: http://dx.doi.org/10.1055/s-2007-965043
Abstract
The introduction of proton transfer reaction mass spectrometry (PTR-MS) for fast response measurements of volatile organic compounds (VOC) has enabled the use of eddy covariance methods to investigate VOC fluxes on the ecosystem scale. In this study PTR-MS flux measurements of VOC were performed over agricultural grassland during and after a cut event. Selected masses detected by the PTR-MS showed fluxes of methanol, acetaldehyde, and acetone. They were highest directly after cutting and during the hay drying phase. Simultaneously, significant fluxes of protonated ion masses 73, 81, and 83 were observed. Due to the limited identification of compounds with the PTR-MS technique, GC-MS and GC-FID-PTR-MS techniques were additionally applied. In this way, ion mass 73 could be identified as 2-butanone, mass 81 mainly as (Z)-3-hexenal, and mass 83 mainly as the sum of (Z)-3-hexenol and hexenyl acetates. Hexenal, hexenols, and the hexenyl acetates are mostly related to plant wounding during cutting. It was found that legume plants and forbs emit a higher number of different VOC species than graminoids.
2009
[Heenan2009] Heenan, S. P., J-P. Dufour, N. Hamid, W. Harvey, and C. M. Delahunty, "Characterisation of fresh bread flavour: Relationships between sensory characteristics and volatile composition", Food Chemistry, vol. 116, no. 1: Elsevier, pp. 249–257, 2009.
Link: http://www.sciencedirect.com/science/article/pii/S0308814609002301
Abstract
The sensory properties and volatile composition of bread flavour were measured to allow improved understanding of perceived bread freshness. Twenty bread varieties consisting of specialty breads (n = 10) and commercial breads (n = 10) were evaluated by descriptive sensory analysis, and volatile composition of all breads was measured by proton transfer reaction mass spectrometry (PTR-MS). The specialty breads (n = 10) studied had been evaluated by consumers, and perceived freshness was known. All sensory attributes and 33 mass ions representative of the PTR-MS spectra significantly (p < 0.05) distinguished between the different breads. Partial least squares regression (PLSR) was used to model and predict sensory profiles as a function of volatile composition for all breads. In addition, a separate model that related volatile composition to known consumer freshness of the 10 specialty breads was created. For each model, accuracy was validated by comparing the differences between predicted and actual, sensory and freshness intensities.
[Jordan2009a] Jordan, A., S. Haidacher, G. Hanel, E. Hartungen, L. Maerk, H. Seehauser, R. Schottkowsky, P. Sulzer, and TD. Maerk, "A Commercial High-Resolution, High-Sensitivity (HRS) PTR-TOF-MS Instrument", CONFERENCE SERIES, pp. 239, 2009.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_4.pdf
[Davison2009] Davison, B., R. Taipale, B. Langford, P. Misztal, S. Fares, G. Matteucci, F. Loreto, JN. Cape, J. Rinne, and CN. Hewitt, "Concentrations and fluxes of biogenic volatile organic compounds above a Mediterranean macchia ecosystem in western Italy", Biogeosciences, vol. 6: EGU, pp. 1655–1670, 2009.
Link: http://nora.nerc.ac.uk/8091/
Abstract
Emission rates and concentrations of biogenic volatile organic compounds (BVOCs) were measured at a Mediterranean coastal site at Castelporziano, approximately 25 km south-west of Rome, between 7 May and 3 June 2007, as part of the ACCENT-VOCBAS field campaign on biosphere–atmosphere interactions. Concentrations and emission rates were measured using the disjunct eddy covariance (DEC) method utilizing three different proton transfer reaction mass spectrometers (PTR-MS) so allowing a comparison between the instruments. The high resolution data from the PTR-MS instruments considerably enhances the original BEMA measurements of the mid 1990s. Depending on the measurement period, the volume mixing ratios were in the range 1.6–3.5 ppbv for methanol, 0.44–1.3 ppbv for acetaldehyde, 0.96–2.1 ppbv for acetone, 0.10–0.14 ppbv for isoprene, and 0.13–0.30 ppbv for monoterpenes. A diurnal cycle in mixing ratios was apparent with daytime maxima for methanol, acetaldehyde, acetone, and isoprene. The fluxes ranged from 370–440 μg m−2 h−1 for methanol, 180–360 μg m−2 h−1 for acetaldehyde, 180–450 μg m−2 h−1 for acetone, 71–290 μg m−2 h−1 for isoprene, and 240–860 μg m−2 h−1 for monoterpenes. From the measured flux data (7 May–3 June) an average basal emission rate for the Macchia vegetation was calculated of 430 μg m−2 h−1 for isoprene and 1100 μg m−2 h−1 for monoterpenes.
2010
[Beauchamp2010a] Beauchamp, J., J. Frasnelli, A. Buettner, M. Scheibe, A. Hansel, and T. Hummel, "Characterization of an olfactometer by proton-transfer-reaction mass spectrometry", Measurement Science and Technology, vol. 21, no. 2, pp. 025801, 2010.
Link: http://stacks.iop.org/0957-0233/21/i=2/a=025801
Abstract
The performance of a commercial olfactometer instrument, which produces odorant pulses of defined duration and concentration, was characterized using proton-transfer-reaction mass spectrometry (PTR-MS). Direct coupling of the PTR-MS instrument with the olfactometer enabled on-line evaluation of the rapidly delivered aroma pulses. Tests were made with a selection of four odorous compounds: hydrogen sulfide, 2,3-butanedione, ethyl butanoate and ethyl hexanoate. Odour concentrations and stimulus durations for these compounds were monitored directly at the olfactometer delivery port via the respective PTR-MS signals. The performance of the olfactometer was found to be dependent on pulse duration. A decrease over time in maximum intensity for identical pulses over an extended duration showed headspace concentration depletions for compounds sourced from a water solution, indicative of gas/liquid partitioning. Such changes were not present using odours sourced from a cylinder or, presumably, when using liquid odours at neat concentrations. In conclusion, while an olfactometer provides stimuli with good reproducibility, the concept is subject to certain limitations that must be appreciated by the experimenter for accurate application of this technique.

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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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