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Scientific Articles - PTR-MS Bibliography

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[Spirig2005] Spirig, C., A. Neftel, C. Ammann, J. Dommen, W. Grabmer, A. Thielmann, A. Schaub, J. Beauchamp, A. Wisthaler, A. Hansel, et al., "Eddy covariance flux measurements of biogenic VOCs during ECHO 2003 using proton transfer reaction mass spectrometry", Atmospheric Chemistry and Physics, vol. 5, no. 2, pp. 465–481, 2005.
Within the framework of the AFO 2000 project ECHO, two PTR-MS instruments were operated in combination with sonic anemometers to determine biogenic VOC fluxes from a mixed deciduous forest site in North-Western Germany. The measurement site was characterised by a forest of inhomogeneous composition, complex canopy structure, limited extension in certain wind directions and frequent calm wind conditions during night time. The eddy covariance (EC) technique was applied since it represents the most direct flux measurement approach on the canopy scale and is, therefore, least susceptible to these non-ideal conditions. A specific flux calculation method was used to account for the sequential multi-component PTR-MS measurements and allowing an individual delay time adjustment as well as a rigorous quality control based on cospectral analysis. The validated flux results are consistent with light and temperature dependent emissions of isoprene and monoterpenes from this forest, with average daytime emissions of 0.94 and 0.3µg m-2s-1, respectively. Emissions of methanol reached on average 0.087µg m-2s-1 during daytime, but fluxes were too small to be detected during night time. Upward fluxes of the isoprene oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) were also found, being two orders of magnitude lower than those of isoprene. Calculations with an analytical footprint model indicate that the observed isoprene fluxes correlate with the fraction of oaks within the footprints of the flux measurement.
[Grabmer2004] Grabmer, W., M. Graus, C. Lindinger, A. Wisthaler, B. Rappenglück, R. Steinbrecher, and A. Hansel, "Disjunct eddy covariance measurements of monoterpene fluxes from a Norway spruce forest using PTR-MS", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 111–115, 2004.
Interest in reliable quantification of organic trace compounds released from terrestrial ecosystems stems from their impact on oxidant levels such as ozone and hydroxyl radicals and on secondary organic aerosol formation. In an attempt to quantify these emissions, a disjunct sampler (DS) was coupled to a PTR-MS instrument. In the disjunct eddy covariance (DEC) technique, an instantaneous grab sample is taken at intervals of tens of seconds and vertical wind speed is recorded at the instant of sample collection. The intermittent periods are used for sample analysis by a moderately fast chemical sensor, in this case a PTR-MS instrument, which allows for fast and sensitive detection of biogenic volatile organic compounds. The vertical turbulent transport of a trace compound is then calculated from the covariance of the fluctuations in vertical wind speed and compound mixing ratio. Fluxes of monoterpenes from a Norway spruce forest were measured during the 2002 summer intensive field campaign of BEWA2000 and results compared well with data obtained using relaxed eddy accumulation (REA) and the enclosure approach. In addition to this field experiment, a laboratory test was carried out to validate the disjunct sampling procedure.
[Graus2003] Graus, M., J. Kreuzwieser, J. Schnitzler, A. Wisthaler, A. Hansel, and H. Rennenberg, "Xylem-Transported Glucose as an Additional Carbon Source for Leaf Isoprene Formation in Quercus Robur L.", EGS-AGU-EUG Joint Assembly, vol. 1, pp. 10692, 2003.
Isoprene is emitted from mature, photosynthesizing leaves of many plant species, particularly of trees. Current interest in understanding the biochemical and physiological mechanisms controlling isoprene formation is caused by the important role isoprene plays in atmospheric chemistry. Isoprene reacts with hydroxyl radicals (OH) thereby generating oxidizing agents such as ozone and organic peroxides. Ozone causes significant deterioration in air quality and can pose threats to human health therefore its control is a major goal in Europe and the United States. In recent years, much progress has been made in elucidating the pathways of isoprene biosynthesis. Nevertheless the regulatory mechanisms controlling isoprene emission are not completely understood. Light and temperature appear to be the main factors controlling short-term variations in isoprene emission. Exposure of plants to C-13 labeled carbon dioxide showed instantaneous assimilated carbon is the primary carbon source for isoprene formation. However, variations in diurnal and seasonal isoprene fluxes, which cannot be explained by temperature, light, and leaf development led to the suggestion that alternative carbon sources may exist contributing to isoprene emissions. The aim of the present study was to test whether xylem-transported carbohydrates act as additional sources for isoprene biosynthesis. For this purpose, [U-C-13] alpha-D-glucose was fed to photosynthesizing leaves via the xylem of Quercus robur L. seedlings and the incorporation of glucose derived C-13 into emitted isoprene was monitored in real time using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS). A rapid incorporation of C-13 from xylem-fed glucose into single (mass 70) and double (mass 71) C-13 labeled isoprene molecules was observed after a lag phase of approximately 5 to 10 minutes. This incorporation was temperature dependent and was highest (up to 13% C-13 of total carbon emitted as isoprene) at the temperature optimum of isoprene emission (40 - 42°C) when net assimilation was strongly reduced. Fast dark-to-light transitions led to a strong single or double C-13 labeling of isoprene from xylem-fed [U-C-13] glucose. During a time period of 10 - 15 minutes up to 86% of all isoprene molecules became single or double C-13 labeled, resulting in a C-13 portion of up to 30% of total carbon emitted as isoprene. The results provide potential evidence that xylem-transported glucose or its degradation products can be used as additional precursors for isoprene biosynthesis and this carbon source becomes more important under conditions of limited photosynthesis.

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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).

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.

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.


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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