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Found 775 results
Title [ Year(Asc)]
2011
[1587] Hörtnagl, L., I. Bamberger, M. Graus, T. M. Ruuskanen, R. Schnitzhofer, M. Müller, A. Hansel, and G. Wohlfahrt, "Biotic, abiotic and management controls on methanol exchange above a temperate mountain grassland.", J Geophys Res Biogeosci, vol. 116, Sep, 2011.
Link: http://dx.doi.org/10.1029/2011jg001641
Abstract
<p>Methanol (CH3OH) fluxes were quantified above a managed temperate mountain grassland in the Stubai Valley (Tyrol, Austria) during the growing seasons 2008 and 2009. Half-hourly methanol fluxes were calculated by means of the virtual disjunct eddy covariance (vDEC) method using 3-dimensional wind data from a sonic anemometer and methanol volume mixing ratios measured with a proton-transfer-reaction mass spectrometer (PTR-MS). During (undisturbed) mature and growing phases methanol fluxes exhibited a clear diurnal cycle with close-to-zero fluxes during nighttime and emissions, up to 10 nmol m(-2) s(-1), which followed the diurnal course of radiation and air temperature. Management events were found to represent the largest perturbations of methanol exchange at the studied grassland ecosystem: Peak emissions of 144.5 nmol m(-2) s(-1) were found during/after cutting of the meadow reflecting the wounding of the plant material and subsequent depletion of the leaf internal aqueous methanol pools. After the application of organic fertilizer, elevated methanol emissions of up to 26.7 nmol m(-2) s(-1) were observed, likely reflecting enhanced microbial activity associated with the applied manure. Simple and multiple linear regression analyses revealed air temperature and radiation as the dominant abiotic controls, jointly explaining 47 % and 70 % of the variability in half-hourly and daily methanol fluxes. In contrast to published leaf-level laboratory studies, the surface conductance and the daily change in the amount of green plant area, used as ecosystem-scale proxies for stomatal conductance and growth, respectively, were found to exert only minor biotic controls on methanol exchange.</p>
[Herbig2011] Herbig, J.., M.. Seger, I.. Kohl, K.. Winkler, H.. Jamnig, A.. Zabernigg, C.. Baumgartner, and A.. Hansel, "Breath Analysis with PTR-MS: More breath markers for lung cancer", 5th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 31-33, 2011.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_5.pdf
Abstract
In a clinical screening study we have measured several hundred subjects using real-time breath analysis with PTR-MS. We present and discuss potential breath markers for lung cancer with a critical view on the data analysis. The presented problems and solutions are also applicable to other analytical methods used in breath analysis.
[Mair2011] Mair, V.., J.. Dunkl, A.. Hansel, and I.. Kohl, "Breath gas analysis by PTR-TOF-MS in a clinical setting", 5th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 231, 2011.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_5.pdf
Abstract
Typical clinical (breath analysis) studies take several months to years. Employing a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) as an analytical tool for breath analysis, a constant performance of the instrument is essential. Here we report on the longterm performance of a PTR-TOF-MS for the analysis of exhaled breath gas in the frame of a clinical study. Performance data are shown for a period of 7 months. We characterized the sampling procedure, sample storage, and measured sensitivity and detection limit for a set of VOCs with relevance in breath analysis. Over the period of 7 months, we were able to achieve a high mass accuracy and precision in the range of ppm.
[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>
[Joo2011] Joó, É., J. Dewulf, C. Amelynck, N. Schoon, O. Pokorska, M. Šimpraga, K. Steppe, M. Aubinet, and H. Van Langenhove, "Constitutive versus heat and biotic stress induced BVOC emissions in Pseudotsuga menziesii", Atmospheric Environment, vol. 45, no. 22: Elsevier, pp. 3655–3662, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S1352231011004377
Abstract
Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under natural environmental conditions, using a dynamic branch enclosure system and GC–MS for their analysis. We determined temperature and light dependency of the individual compounds, studied seasonality of the emissions and discuss the effect of heat stress in comparison with two specific biotic stresses that occurred naturally on the trees. A standardized emission rate of 6.8 μg g(dw)−1 h−1 for monoterpenes under stressed conditions was almost a magnitude higher than that obtained for healthy trees (0.8 ± 0.2 μg g(dw)−1 h−1), with higher beta factors characterizing the stressed trees. The response of the emissions to light intensity was different for the individual compounds, suggesting a distinct minimum light intensity to reach saturation. Heat stress changed the relative contribution of specific volatiles, with larger extent of increase of sesquiterpenes, methyl salicylate and linalool emissions compared to monoterpenes. Biotic stress kept low the emissions of sesquiterpenes, (E)-4,8-dimethyl-1,3,7-nonatriene and methylbutenol isomers, and increased the level of methyl salicylate and monoterpenes. The ratio of β-pinene/α-pinene was also found to be significantly enhanced from 1.3 to 2.4 and 3.2 for non-stressed, heat stressed and combined biotic and heat stressed, respectively.
[Cappellin2011a] Cappellin, L., F. Biasioli, P. M. Granitto, E. Schuhfried, C. Soukoulis, F. Costa, T. D. Maerk, and F. Gasperi, "On data analysis in PTR-TOF-MS: From raw spectra to data mining", Sensors and actuators B: Chemical, vol. 155, no. 1: Elsevier, pp. 183–190, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S0925400510009135
Abstract
Recently the coupling of proton transfer reaction ionization with a time-of-flight mass analyser (PTR-TOF-MS) has been proposed to realise a volatile organic compound (VOC) detector that overcomes the limitations in terms of time and mass resolution of the previous instrument based on a quadrupole mass analysers (PTR-Quad-MS). This opens new horizons for research and allows for new applications in fields where the rapid and sensitive monitoring and quantification of volatile organic compounds (VOCs) is crucial as, for instance, environmental sciences, food sciences and medicine. In particular, if coupled with appropriate data mining methods, it can provide a fast MS-nose system with rich analytical information. The main, perhaps even the only, drawback of this new technique in comparison to its precursor is related to the increased size and complexity of the data sets obtained. It appears that this is the main limitation to its full use and widespread application. Here we present and discuss a complete computer-based strategy for the data analysis of PTR-TOF-MS data from basic mass spectra handling, to the application of up-to date data mining methods. As a case study we apply the whole procedure to the classification of apple cultivars and clones, which was based on the distinctive profiles of volatile organic compound emissions.
[Bamberger2011] Bamberger, I., L. Hörtnagl, TM. Ruuskanen, R. Schnitzhofer, M. Müller, M. Graus, T. Karl, G. Wohlfahrt, and A. Hansel, "Deposition fluxes of terpenes over grassland", Journal of Geophysical Research: Atmospheres (1984–2012), vol. 116, no. D14: Wiley Online Library, 2011.
Link: http://onlinelibrary.wiley.com/doi/10.1029/2010JD015457/full
Abstract
Eddy covariance flux measurements were carried out for two subsequent vegetation periods above a temperate mountain grassland in an alpine valley using a proton-transfer-reaction-mass spectrometer (PTR-MS) and a PTR time-of-flight-mass spectrometer (PTR-TOF). In 2008 and during the first half of the vegetation period 2009 the volume mixing ratios (VMRs) for the sum of monoterpenes (MTs) were typically well below 1 ppbv and neither MT emission nor deposition was observed. After a hailstorm in July 2009 an order of magnitude higher amount of terpenes was transported to the site from nearby coniferous forests causing elevated VMRs. As a consequence, deposition fluxes of terpenes to the grassland, which continued over a time period of several weeks without significant reemission, were observed. For days without precipitation the deposition occurred at velocities close to the aerodynamic limit. In addition to monoterpene uptake, deposition fluxes of the sum of sesquiterpenes (SQTs) and the sum of oxygenated terpenes (OTs) were detected. Considering an entire growing season for the grassland (i.e., 1 April to 1 November 2009), the cumulative carbon deposition of monoterpenes reached 276 mg C m−2. This is comparable to the net carbon emission of methanol (329 mg C m−2), which is the dominant nonmethane volatile organic compound (VOC) emitted from this site, during the same time period. It is suggested that deposition of monoterpenes to terrestrial ecosystems could play a more significant role in the reactive carbon budget than previously assumed.
[Jordan2011] Jordan, A., P. and Watts, and C. A. Mayhew, "Detection and Identification of Illicit and Hazardous Substances with Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)", : IONICON Analytik, 2011.
Link: http://blog.ionicon.com/wp-content/uploads/2011/08/future-security-ionicon-extended_abstract.pdf
[Sulzer2011] Sulzer, P., A. Jordan, G. Hanel, E. Hartungen, H. Seehauser, L. Märk, S. Haidacher, R. Schottkowsky, KH. Becker, and TD. Märk, "Detection of explosives Detection of explosives with Proton Transfer Reaction Transfer Reaction-Mass Spectrometry Mass Spectrometry", , 2011.
Link: http://www.ionicon.com/downloads/IONICON_Illicit-substances-detection_PTR-MS.pdf
[Brilli2011] Brilli, F., T. M. Ruuskanen, R. Schnitzhofer, M. Müller, M. Breitenlechner, V. Bittner, G. Wohlfahrt, F. Loreto, and A. Hansel, "Detection of plant volatiles after leaf wounding and darkening by proton transfer reaction "time-of-flight" mass spectrometry (PTR-TOF).", PLoS One, vol. 6, no. 5: Ionicon Analytik G.m.b.H., Innsbruck, Austria., pp. e20419, 2011.
Link: http://dx.doi.org/10.1371/journal.pone.0020419
Abstract
Proton transfer reaction-time of flight (PTR-TOF) mass spectrometry was used to improve detection of biogenic volatiles organic compounds (BVOCs) induced by leaf wounding and darkening. PTR-TOF measurements unambiguously captured the kinetic of the large emissions of green leaf volatiles (GLVs) and acetaldehyde after wounding and darkening. GLVs emission correlated with the extent of wounding, thus confirming to be an excellent indicator of mechanical damage. Transient emissions of methanol, C5 compounds and isoprene from plant species that do not emit isoprene constitutively were also detected after wounding. In the strong isoprene-emitter Populus alba, light-dependent isoprene emission was sustained and even enhanced for hours after photosynthesis inhibition due to leaf cutting. Thus isoprene emission can uncouple from photosynthesis and may occur even after cutting leaves or branches, e.g., by agricultural practices or because of abiotic and biotic stresses. This observation may have important implications for assessments of isoprene sources and budget in the atmosphere, and consequences for tropospheric chemistry.
[Han2011] Han, KH., JS. Zhang, H. Nellemose Knudsen, P. Wargocki, H. Chen, PK. Varshney, and B. Guo, "Development of a novel methodology for indoor emission source identification", Atmospheric Environment, vol. 45, no. 18: Pergamon, pp. 3034–3045, 2011.
Link: http://works.bepress.com/cgi/viewcontent.cgi?article=1004&amp;context=shimsong
Abstract
The objective of this study was to develop and evaluate a methodology to identify individual sources of emissions based on the measurements of mixed air samples and the emission signatures of individual materials previously determined by Proton Transfer Reaction-Mass Spectrometry (PTR-MS), an on-line analytical device. The methodology based on signal processing principles was developed by employing the method of multiple regression least squares (MRLS) and a normalization technique. Samples of nine typical building materials were tested individually and in combination, including carpet, ceiling material, gypsum board, linoleum, two paints, polyolefine, PVC and wood. Volatile Organic Compound (VOC) emissions from each material were measured in a 50-liter small-scale chamber. Chamber air was sampled by PTR-MS to establish a database of emission signatures unique to each individual material. The same task was performed to measure combined emissions from material mixtures for the application and validation of the developed signal separation method. Results showed that the proposed method could identify the individual sources under laboratory conditions with two, three, five and seven materials present. Further experiments and investigation are needed for cases where the relative emission rates among different compounds may change over a long-term period.
[1492] Misztal, P.. K., E.. Nemitz, B.. Langford, C.. F. Di Marco, G.. J. Phillips, C.. N. Hewitt, A.. R. MacKenzie, S.. M. Owen, D.. Fowler, M.. R. Heal, et al., "Direct ecosystem fluxes of volatile organic compounds from oil palms in South-East Asia", Atmospheric Chemistry and Physics, vol. 11, pp. 8995–9017, 2011.
Link: http://www.atmos-chem-phys.net/11/8995/2011/
Abstract
<p>This paper reports the first direct eddy covariance fluxes of reactive biogenic volatile organic compounds (BVOCs) from oil palms to the atmosphere using proton-transfer-reaction mass spectrometry (PTR-MS), measured at a plantation in Malaysian Borneo. At midday, net isoprene flux constituted the largest fraction (84 %) of all emitted BVOCs measured, at up to 30 mg m&minus;2 h&minus;1 over 12 days. By contrast, the sum of its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) exhibited clear deposition of 1 mg m&minus;2 h&minus;1, with a small average canopy resistance of 230 s m&minus;1. Approximately 15 % of the resolved BVOC flux from oil palm trees could be attributed to floral emissions, which are thought to be the largest reported biogenic source of estragole and possibly also toluene. Although on average the midday volume mixing ratio of estragole exceeded that of toluene by almost a factor of two, the corresponding fluxes of these two compounds were nearly the same, amounting to 0.81 and 0.76 mg m&minus;2 h&minus;1, respectively. By fitting the canopy temperature and PAR response of the MEGAN emissions algorithm for isoprene and other emitted BVOCs a basal emission rate of isoprene of 7.8 mg m&minus;2 h&minus;1 was derived. We parameterise fluxes of depositing compounds using a resistance approach using direct canopy measurements of deposition. Consistent with Karl et al. (2010), we also propose that it is important to include deposition in flux models, especially for secondary oxidation products, in order to improve flux predictions.</p>
[Biasioli2011] Biasioli, F., C. Yeretzian, T. D. Märk, J. Dewulf, and H. Van Langenhove, "Direct-injection mass spectrometry adds the time dimension to (B) VOC analysis", TrAC Trends in Analytical Chemistry, vol. 30, no. 7: Elsevier, pp. 1003–1017, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S0165993611001269
Abstract
In the past decade, we have witnessed rapid development of direct-injection mass spectrometric (DIMS) technologies that combine ever-improving mass and time resolution with high sensitivity and robustness. Here, we review some of the most significant DIMS technologies, which have been applied to rapid monitoring and quantification of volatile organic compounds (VOCs) and biogenic VOCS (BVOCs). They include MS-e-noses, atmospheric-pressure chemical ionization (APCI), proton-transfer-reaction mass spectrometry (PTR-MS), and selected ion-flow-tube mass spectrometry (SIFT-MS). DIMS-based MS-e-noses provide the possibility to screen large sample sets and may yield rich analytical information. APCI is a widespread ionization method and pioneered DIMS in environmental and flavor-release applications. SIFT-MS and PTR-MS allow better control of precursor-ion generation and hence of the ionization process. SIFT-MS puts the focus on control of the ionization process, while PTR-MS does so on sensitivity. Most (B)VOCs of interest can be efficiently detected and often identified by DIMS, thanks also to the possibility of switching between different precursor ions and the recent realization of time-of-flight-based equipments. Finally, we give selected examples of applications for each of the key technologies, including research in food-quality control (MS-e-nose), flavor release (APCI), environmental sciences (PTR-MS) and health sciences (SIFT-MS).
[Kamysek2011] Kamysek, S., P. Fuchs, H. Schwoebel, J. P. Roesner, S. Kischkel, K. Wolter, C. Loeseken, J. K. Schubert, and W. Miekisch, "Drug detection in breath: effects of pulmonary blood flow and cardiac output on propofol exhalation.", Anal Bioanal Chem, vol. 401, no. 7: Department of Anesthesiology and Intensive Care, University of Rostock, Schillingallee 35, 18057 Rostock, Germany., pp. 2093–2102, Oct, 2011.
Link: http://dx.doi.org/10.1007/s00216-011-5099-8
Abstract
Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in an increased CO on propofol breath concentrations and on the correlation between propofol blood and breath concentrations were investigated in seven acutely instrumented pigs. Discontinuous propofol determination in breath by means of alveolar sampling and SPME-GC-MS showed good agreement (R(2)=0.959) with continuous alveolar real-time measurement by means of PTR-MS. In all investigated animals, increasing cardiac output led to a deterioration of the relationship between breath and blood propofol concentrations (R(2)=0.783 for gas chromatography-mass spectrometry and R(2)=0.795 for PTR-MS). Decreasing pulmonary blood flow and cardiac output through banding of the pulmonary artery did not significantly affect the relationship between propofol breath and blood concentrations (R(2)>0.90). Estimation of propofol blood concentrations from exhaled alveolar concentrations seems possible by means of different analytical methods even when cardiac output is decreased. Increases in cardiac output preclude prediction of blood propofol concentration from exhaled concentrations.
[Deleris2011a] Déléris, I., A. Saint-Eve, F. Dakowski, E. Sémon, J-L. Le Quéré, H. Guillemin, and I. Souchon, "The dynamics of aroma release during consumption of candies of different structures, and relationship with temporal perception", Food Chemistry, vol. 127, no. 4: Elsevier, pp. 1615–1624, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S0308814611002858
Abstract
We investigated the role of both candy texture and eating technique (melting or chewing) on the dynamics of aroma release. One novelty of this type of analysis was the simultaneous application of instrumental and sensory analysis. Four candy textures were established based on their storage modulus at 1 Hz by varying the gelatine content between 0 and 15% w/w. The invivo release of three aroma compounds was monitored using Proton Transfer Reaction Mass Spectrometry and with a trained panel of testers. The gelatine content had no significant effect on the headspace/product partition and diffusion properties of the aroma compounds. The highest invivo release for all aroma compounds was obtained with the 2% gelatine sample. Our findings indicated that aroma release was determined by interaction between the product properties and oral behaviour. Relations between the dynamics of release and perception (method of Temporal Dominance of Sensations) have been established on temporal parameters.
[Ruuskanen2011] Ruuskanen, TM., M. Müller, R. Schnitzhofer, T. Karl, M. Graus, I. Bamberger, L. Hoertnagl, F. Brilli, G. Wohlfahrt, and A. Hansel, "Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF", Atmos. Chem. Phys, vol. 11, pp. 611–625, 2011.
Link: http://www.atmos-chem-phys.net/11/611/2011/acp-11-611-2011.html
Abstract
Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5–20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+ – water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes.
[1489] Gordon, S.. M., M.. C. Brinkman, R.. Q. Meng, G.. M. Anderson, J.. C. Chuang, R.. R. Kroeger, I.. L. Reyes, and P.. I. Clark, "Effect of Cigarette Menthol Content on Mainstream Smoke Emissions", Chemical Research in Toxicology, vol. 24, pp. 1744-1753, 2011.
Link: http://pubs.acs.org/doi/abs/10.1021/tx200285s
Abstract
<p>The 2009 Family Smoking Prevention and Tobacco Control Act empowered the U.S. Food and Drug Administration to study &ldquo;the impact of the use of menthol in cigarettes on the public health, including such use among children, African Americans, Hispanics and other racial and ethnic minorities,&rdquo; and develop recommendations. Current scientific evidence comparing human exposures between menthol and nonmenthol smokers shows mixed results. This is largely because of the many differences between commercial menthol and nonmenthol cigarettes other than their menthol content. We conducted an innovative study using two types of test cigarettes: a commercial nonmenthol brand that we mentholated at four different levels, and Camel Crush, a commercial cigarette containing a small capsule in the filter that releases menthol solution into the filter when crushed. Cigarettes were machine-smoked at each of the menthol levels investigated, and the total particulate matter (TPM) was collected on a quartz fiber filter pad and analyzed by gas chromatography/mass spectrometry for menthol, nicotine, tobacco-specific nitrosamines (TSNAs), polycyclic aromatic hydrocarbons (PAHs), cotinine, and quinoline. The mainstream smoke was also monitored continuously in real time on a puff-by-puff basis for seven gas-phase constituents (acetaldehyde, acetonitrile, acrylonitrile, benzene, 1,3-butadiene, isoprene, and 2,5-dimethylfuran), using a proton transfer reaction-mass spectrometer. Average yields (in micrograms/cigarette) for the analytes were determined. Menthol in the TPM samples increased linearly with applied menthol concentration, but the amounts of nicotine along with the target TSNAs, PAHs, cotinine, and quinoline in the cigarettes remained essentially unchanged. Similarly, yields of the targeted volatile organic compounds (VOCs) in whole smoke from the mentholated nonmenthol cigarettes that were measured in real-time were largely unaffected by their menthol levels. In the Camel Crush cigarettes, however, the VOC yields appeared to increase in the presence of menthol, especially in the gas phase. Although we succeeded in characterizing key mainstream smoke constituents in cigarettes that differ only in menthol content, further study is needed to definitively answer whether menthol affects exposure to selected cigarette constituents and thereby influences harm.</p>
[Liu2011] Liu, D., A. Feilberg, A. P. S. Adamsen, and K. E. N. Jonassen, "The effect of slurry treatment including ozonation on odorant reduction measured by in-situ PTR-MS", Atmospheric Environment, vol. 45, no. 23: Elsevier, pp. 3786–3793, 2011.
Link: http://www.sciencedirect.com/science/article/pii/S1352231011004067
Abstract
The emission of odorous compounds from intensive pig production facilities is a nuisance for neighbors. Slurry ozonation for odor abatement has previously been demonstrated in laboratory scale. In this study, the effect of slurry ozonation (combined with solid–liquid pre-separation and acidification) on emissions of odorous compounds was tested in an experimental full-scale growing pig facility using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for online analysis of odorants. The measurements were performed to gain a better understanding of the effects of ozone treatment on emissions odorous compounds and to identify potential options for optimization of ozone treatment. The compounds monitored included volatile sulfur compounds, amine, carboxylic acids, ketones, phenols and indoles. Measurements were performed during nearly a one-month period in summertime. The compounds with the highest concentrations observed in the ventilation exhaust duct were acetic acid, hydrogen sulfide, propanoic acid and butanoic acid. The compounds with the highest removal efficiencies were hydrogen sulfide, 3-methyl-indole, phenol and acetic acid. Based on odor threshold values, methanethiol, butanoic acid, 4-methylphenol, hydrogen sulfide and C5 carboxylic acids are estimated to contribute significantly to the odor nuisance. Emissions of odorous compounds were observed to be strongly correlated with temperature with the exception of hydrogen sulfide. Emission peaks of sulfur compounds were seen during slurry handling activities. Discharging of the slurry pit led to reduced hydrogen sulfide emissions, but emissions of most other odorants were not affected. The results indicate that emissions of odorants other than hydrogen sulfide mainly originate from sources other than the treated slurry, which limits the potential for further optimization. The PTR-MS measurements are demonstrated to provide a quantitative, accurate and detailed evaluation of ozone treatment for emission reduction.
[Saha2011] Saha, C. Kumer, A. Feilberg, G. Zhang, and A. Peter S. Adamsen, "Effects of airflow on odorants' emissions in a model pig house - A laboratory study using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS).", Sci Total Environ, vol. 410-411: Department of Engineering, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark. cksahabau@yahoo.com, pp. 161–171, Dec, 2011.
Link: http://dx.doi.org/10.1016/j.scitotenv.2011.09.017
Abstract
Identification of different factors that affect emissions of gasses, including volatile organic compounds (VOCs) is necessary to develop emission abatement technology. The objectives of this research were to quantify and study temporal variation of gas emissions from a model pig house under varying ventilation rates. The used model was a 1:12.5 scale of a section of a commercial finishing pig house. The VOC concentrations at inlet, outlet, and slurry pit of the model space were measured using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS). PTR-MS can measure the temporal variations of odor compounds' emission from the slurry pit in real time. The emissions of H(2)S and 14 VOCs were lower compared to real pig buildings except for ammonia, which indicated possible other sources of those compounds than the slurry in the slurry pit. The ventilation rate affected significantly on ammonia and trimethylamine emission (p<0.05). The hydrogen sulfide (H(2)S) emission was independent of the ventilation rate. VFAs' emission dependency on ventilation rate increased with the increase of carbon chain. Phenols, indoles and ketones showed the positive correlation with ventilation rate to some extent. Generally, compounds with high solubility (low Henry's constant) showed stronger correlation with ventilation rates than the compounds with high Henry's constant.
[1490] Gordon, S. M., M. C. Brinkman, R. Q. Meng, G. M. Anderson, J. C. Chuang, P. I. Clark, and P. A. Richter3, "Effects of Mentholation on Cigarette Smoke Emissions", Conference of the Society for Research on Nicotine and Tobacco (SRNT), Toronto, Canada, Conference of the Society for Research on Nicotine and Tobacco (SRNT), Feb., 2011.
Link: http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/TobaccoProductsScientificAdvisoryCommittee/UCM238839.pdf
[Singh2011] Singh, S. K., G. A. Strobel, B. Knighton, B. Geary, J. Sears, and D. Ezra, "An endophytic Phomopsis sp. possessing bioactivity and fuel potential with its volatile organic compounds", Microbial ecology, vol. 61, no. 4: Springer, pp. 729–739, 2011.
Link: http://link.springer.com/article/10.1007/s00248-011-9818-7
Abstract
An unusual Phomopsis sp. was isolated as endophyte of Odontoglossum sp. (Orchidaceae), associated with a cloud forest in Northern Ecuador. This fungus produces a unique mixture of volatile organic compounds (VOCs) including sabinene (a monoterpene with a peppery odor) only previously known from higher plants. In addition, some of the other more abundant VOCs recorded by GC/MS in this organism were 1-butanol, 3-methyl; benzeneethanol; 1-propanol, 2-methyl and 2-propanone. The gases of Phomopsis sp. possess antifungal properties and an artificial mixture of the VOCs mimicked the antibiotic effects of this organism with the greatest bioactivity against a wide range of plant pathogenic test fungi including: Pythium, Phytophthora, Sclerotinia, Rhizoctonia, Fusarium, Botrytis, Verticillium, and Colletotrichum. The IC50 values for the artificial gas mixture of Phomopsis sp. varied between 8 and 25.65 μl/mL. Proton transfer reaction-mass spectrometry monitored the concentration of VOCs emitted by Phomopsis sp. and yielded a total VOC concentration of ca. 18 ppmv in the head space at the seventh day of incubation at 23°C on PDA. As with many VOC-producing endophytes, this Phomopsis sp. did survive and grow in the presence of the inhibitory gases of Muscodor albus. A discussion is presented on the possible involvement of VOC production by the fungus and its role in the biology/ecology of the fungus/plant/environmental relationship.
[Fischer2011] Fischer, L.., K.. Winkler, R.. Gutmann, W.. Singer, J.. Herbig, and A.. Hansel, "Evaporating Liquid Samples for Analysis with PTR-MS", 5th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 211–212, 2011.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_5.pdf
Abstract
We present a method for measuring liquid samples with the PTR-MS by using a spray to convert the liquid into the gas phase. Advantages over headspace measurements concerning compounds with high Henry's law constants could be demonstrated.

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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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