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Found 11 results
Title [ Year(Asc)]
Filters: Author is Müller, Markus  [Clear All Filters]
2016
[1792] Halliday, H. S., A. M. Thompson, A. Wisthaler, D. R. Blake, R. S. Hornbrook, T. Mikoviny, M. Müller, P. Eichler, E. C. Apel, and A. J. Hills, "Atmospheric benzene observations from oil and gas production in the Denver-Julesburg Basin in July and August 2014", Journal of Geophysical Research: Atmospheres, vol. 121, 2016.
Link: http://onlinelibrary.wiley.com/doi/10.1002/2016JD025327/abstract
Abstract
<p>High time resolution measurements of volatile organic compounds (VOCs) were collected using a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the Platteville Atmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (O&amp;NG) development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA&#39;s &ldquo;Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality&rdquo; (DISCOVER-AQ) field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene&thinsp;=&thinsp;0.53 ppbv, maximum benzene&thinsp;=&thinsp;29.3 ppbv), primarily at night (mean nighttime benzene&thinsp;=&thinsp;0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&amp;NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&amp;NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO.</p>
[1795] Schroeder, J. R., J. H. Crawford, A. Fried, J. Walega, A. Weinheimer, A. Wisthaler, M. Müller, T. Mikoviny, G. Chen, M. Shook, et al., "Formaldehyde column density measurements as a suitable pathway to estimate near-surface ozone tendencies from space", Journal of Geophysical Research: Atmospheres, vol. 121, 2016.
Link: http://onlinelibrary.wiley.com/doi/10.1002/2016JD025419/full
Abstract
<p>In support of future satellite missions that aim to address the current shortcomings in measuring air quality from space, NASA&#39;s Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign was designed to enable exploration of relationships between column measurements of trace species relevant to air quality at high spatial and temporal resolution. In the DISCOVER-AQ data set, a modest correlation (r2&thinsp;=&thinsp;0.45) between ozone (O3) and formaldehyde (CH2O) column densities was observed. Further analysis revealed regional variability in the O3-CH2O relationship, with Maryland having a strong relationship when data were viewed temporally and Houston having a strong relationship when data were viewed spatially. These differences in regional behavior are attributed to differences in volatile organic compound (VOC) emissions. In Maryland, biogenic VOCs were responsible for &nbsp;28% of CH2O formation within the boundary layer column, causing CH2O to, in general, increase monotonically throughout the day. In Houston, persistent anthropogenic emissions dominated the local hydrocarbon environment, and no discernable diurnal trend in CH2O was observed. Box model simulations suggested that ambient CH2O mixing ratios have a weak diurnal trend (&plusmn;20% throughout the day) due to photochemical effects, and that larger diurnal trends are associated with changes in hydrocarbon precursors. Finally, mathematical relationships were developed from first principles and were able to replicate the different behaviors seen in Maryland and Houston. While studies would be necessary to validate these results and determine the regional applicability of the O3-CH2O relationship, the results presented here provide compelling insight into the ability of future satellite missions to aid in monitoring near-surface air quality.</p>
[1791] Müller, M., B. E. Anderson, A. J. Beyersdorf, J. H. Crawford, G. S. Diskin, P. Eichler, A. Fried, F. N. Keutsch, T. Mikoviny, K. L. Thornhill, et al., "In situ measurements and modeling of reactive trace gases in a small biomass burning plume", Atmospheric Chemistry and Physics, vol. 16, pp. 3813–3824, 2016.
Link: http://www.atmos-chem-phys.net/16/3813/2016/
Abstract
<p>An instrumented NASA P-3B aircraft was used for airborne sampling of trace gases in a plume that had emanated from a small forest understory fire in Georgia, USA. The plume was sampled at its origin to derive emission factors and followed &thinsp;&sim;&thinsp;13.6 km downwind to observe chemical changes during the first hour of atmospheric aging. The P-3B payload included a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), which measured non-methane organic gases (NMOGs) at unprecedented spatiotemporal resolution (10 m spatial/0.1 s temporal). Quantitative emission data are reported for CO2, CO, NO, NO2, HONO, NH3, and 16 NMOGs (formaldehyde, methanol, acetonitrile, propene, acetaldehyde, formic acid, acetone plus its isomer propanal, acetic acid plus its isomer glycolaldehyde, furan, isoprene plus isomeric pentadienes and cyclopentene, methyl vinyl ketone plus its isomers crotonaldehyde and methacrolein, methylglyoxal, hydroxy acetone plus its isomers methyl acetate and propionic acid, benzene, 2,3-butanedione, and 2-furfural) with molar emission ratios relative to CO larger than 1 ppbV ppmV&minus;1. Formaldehyde, acetaldehyde, 2-furfural, and methanol dominated NMOG emissions. No NMOGs with more than 10 carbon atoms were observed at mixing ratios larger than 50 pptV ppmV&minus;1 CO. Downwind plume chemistry was investigated using the observations and a 0-D photochemical box model simulation. The model was run on a nearly explicit chemical mechanism (MCM v3.3) and initialized with measured emission data. Ozone formation during the first hour of atmospheric aging was well captured by the model, with carbonyls (formaldehyde, acetaldehyde, 2,3-butanedione, methylglyoxal, 2-furfural) in addition to CO and CH4 being the main drivers of peroxy radical chemistry. The model also accurately reproduced the sequestration of NOx into peroxyacetyl nitrate (PAN) and the OH-initiated degradation of furan and 2-furfural at an average OH concentration of 7.45 &plusmn; 1.07 &times; 106 cm&minus;3 in the plume. Formaldehyde, acetone/propanal, acetic acid/glycolaldehyde, and maleic acid/maleic anhydride (tentatively identified) were found to be the main NMOGs to increase during 1 h of atmospheric plume processing, with the model being unable to capture the observed increase. A mass balance analysis suggests that about 50 % of the aerosol mass formed in the downwind plume is organic in nature.</p>
2015
[1624] Hu, L., D. B. Millet, M. Baasandorj, T. J. Griffis, K. R. Travis, C. W. Tessum, J. D. Marshall, W. F. Reinhart, T. Mikoviny, M. Müller, et al., "Emissions of C 6 -C 8 aromatic compounds in the United States: Constraints from tall tower and aircraft measurements", Journal of Geophysical Research: Atmospheres, vol. 120, pp. 826–842, Jan, 2015.
Link: http://dx.doi.org/10.1002/2014JD022627
Abstract
<p>We present two full years of continuous C6&ndash;C8 aromatic compound measurements by PTR-MS at the KCMP tall tower (Minnesota, US) and employ GEOS-Chem nested grid simulations in a Bayesian inversion to interpret the data in terms of new constraints on US aromatic emissions. Based on the tall tower data, we find that the RETRO inventory (year-2000) overestimates US C6&ndash;C8 aromatic emissions by factors of 2.0&ndash;4.5 during 2010&ndash;2011, likely due in part to post-2000 reductions. Likewise, our implementation of the US EPA&#39;s NEI08 overestimates the toluene flux by threefold, reflecting an inventory bias in non-road emissions plus uncertainties associated with species lumping. Our annual top-down emission estimates for benzene and C8 aromatics agree with the NEI08 bottom-up values, as does the inferred contribution from non-road sources. However, the NEI08 appears to underestimate on-road emissions of these compounds by twofold during the warm season. The implied aromatic sources upwind of North America are more than double the prior estimates, suggesting a substantial underestimate of East Asian emissions, or large increases there since 2000. Long-range transport exerts an important influence on ambient benzene over the US: on average 43% of its wintertime abundance in the US Upper Midwest is due to sources outside North America. Independent aircraft measurements show that the inventory biases found here for C6&ndash;C8 aromatics also apply to other parts of the US, with notable exceptions for toluene in California and Houston, Texas. Our best estimates of year-2011 contiguous US emissions are 206 (benzene), 408 (toluene), and 822 (C8 aromatics) GgC.</p>
[1794] Hu, L., D. B. Millet, M. Baasandorj, T. J. Griffis, K. R. Travis, C. W. Tessum, J. D. Marshall, W. F. Reinhart, T. Mikoviny, M. Müller, et al., "Emissions of C6–C8 aromatic compounds in the United States: Constraints from tall tower and aircraft measurements", Journal of Geophysical Research: Atmospheres, vol. 120, pp. 826–842, 2015.
Link: http://onlinelibrary.wiley.com/doi/10.1002/2014JD022627/abstract
Abstract
<p>We present two full years of continuous C6&ndash;C8 aromatic compound measurements by PTR-MS at the KCMP tall tower (Minnesota, US) and employ GEOS-Chem nested grid simulations in a Bayesian inversion to interpret the data in terms of new constraints on US aromatic emissions. Based on the tall tower data, we find that the RETRO inventory (year-2000) overestimates US C6&ndash;C8 aromatic emissions by factors of 2.0&ndash;4.5 during 2010&ndash;2011, likely due in part to post-2000 reductions. Likewise, our implementation of the US EPA&#39;s NEI08 overestimates the toluene flux by threefold, reflecting an inventory bias in non-road emissions plus uncertainties associated with species lumping. Our annual top-down emission estimates for benzene and C8 aromatics agree with the NEI08 bottom-up values, as does the inferred contribution from non-road sources. However, the NEI08 appears to underestimate on-road emissions of these compounds by twofold during the warm season. The implied aromatic sources upwind of North America are more than double the prior estimates, suggesting a substantial underestimate of East Asian emissions, or large increases there since 2000. Long-range transport exerts an important influence on ambient benzene over the US: on average 43% of its wintertime abundance in the US Upper Midwest is due to sources outside North America. Independent aircraft measurements show that the inventory biases found here for C6&ndash;C8 aromatics also apply to other parts of the US, with notable exceptions for toluene in California and Houston, Texas. Our best estimates of year-2011 contiguous US emissions are 206 (benzene), 408 (toluene), and 822 (C8 aromatics) GgC.</p>
[1793] Sun, K., K. Cady-Pereira, D. J. Miller, L. Tao, M. A. Zondlo, J. B. Nowak, JA. Neuman, T. Mikoviny, M. Müller, A. Wisthaler, et al., "Validation of TES ammonia observations at the single pixel scale in the San Joaquin Valley during DISCOVER-AQ", Journal of Geophysical Research: Atmospheres, vol. 120, pp. 5140–5154, 2015.
Link: http://onlinelibrary.wiley.com/doi/10.1002/2014JD022846/full
Abstract
<p>Ammonia measurements from a vehicle-based, mobile open-path sensor and those from aircraft were compared with Tropospheric Emission Spectrometer (TES) NH3 columns at the pixel scale during the NASA Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality field experiment. Spatial and temporal mismatches were reduced by having the mobile laboratory sample in the same areas as the TES footprints. To examine how large heterogeneities in the NH3 surface mixing ratios may affect validation, a detailed spatial survey was performed within a single TES footprint around the overpass time. The TES total NH3 column above a single footprint showed excellent agreement with the in situ total column constructed from surface measurements with a difference of 2% (within the combined measurement uncertainties). The comparison was then extended to a TES transect of nine footprints where aircraft data (5&ndash;80&thinsp;ppbv) were available in a narrow spatiotemporal window (&lt;10&thinsp;km, &lt;1&thinsp;h). The TES total NH3 columns above the nine footprints agreed to within 6% of the in situ total columns derived from the aircraft-based measurements. Finally, to examine how TES captures surface spatial gradients at the interpixel scale, ground-based, mobile measurements were performed directly underneath a TES transect, covering nine footprints within &plusmn;1.5&thinsp;h of the overpass. The TES total columns were strongly correlated (R2&thinsp;=&thinsp;0.82) with the median NH3 mixing ratios measured at the surface. These results provide the first in situ validation of the TES total NH3 column product, and the methodology is applicable to other satellite observations of short-lived species at the pixel scale.</p>
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>
[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.
2010
[Graus2010] Graus, M., M. Müller, and A. Hansel, "High resolution PTR-TOF: quantification and formula confirmation of VOC in real time.", J Am Soc Mass Spectrom, vol. 21, no. 6: University of Innsbruck, Institute of Ion Physics and Applied Physics, Innsbruck, Austria., pp. 1037–1044, Jun, 2010.
Link: http://dx.doi.org/10.1016/j.jasms.2010.02.006
Abstract
We present the unprecedented capability to identify and quantify volatile organic compounds (VOCs) by means of proton transfer reaction time-of-flight (PTR-TOF) mass spectrometry on-line with high time resolution. A mass resolving power of 4000-5000 and a mass accuracy of 2.5 ppm allow for the unambiguous sum-formula identification of hydrocarbons (HCs) and oxygenated VOCs (OVOCs). Test masses measured over an 11-wk period are very precise (SD < 3.4 ppm) and the mass resolving power shows good stability (SD < 5%). Based on a 1 min time resolution, we demonstrate a detection limit in the low pptv range featuring a dynamic range of six orders of magnitude. Sub-ppbv VOC concentrations are analyzed within a second; sub-pptv detection limits are achieved within a few tens of minutes. We present a thorough characterization of our recently developed PTR-TOF system and address application fields for the new instrument.
2009
[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.
2008
[Mielke2008] Mielke, L. H., D. E. Erickson, S. A. McLuckey, M. Müller, A. Wisthaler, A. Hansel, and P. B. Shepson, "Development of a proton-transfer reaction-linear ion trap mass spectrometer for quantitative determination of volatile organic compounds.", Anal Chem, vol. 80, no. 21: Department of Chemistry, Purdue University, 860 Oval Drive West, Lafayette, Indiana 47907-2084, USA., pp. 8171–8177, Nov, 2008.
Link: http://dx.doi.org/10.1021/ac801328d
Abstract
Currently, proton-transfer reaction mass spectrometry (PTR-MS) allows for quantitative determination of volatile organic compounds in real time at concentrations in the low ppt range, but cannot differentiate isomers or isobaric molecules, using the conventional quadrupole mass filter. Here we pursue the application of linear quadrupole ion trap (LIT) mass spectrometry in combination with proton-transfer reaction chemical ionization to provide the advantages of specificity from MS/MS. A commercial PTR-MS platform composed of a quadrupole mass filter with the addition of end cap electrodes enabled the mass filter to operate as a linear ion trap. The rf drive electronics were adapted to enable the application of dipolar excitation to opposing rods, for collision-induced dissociation (CID) of trapped ions. This adaptation enabled ion isolation, ion activation, and mass analysis. The utility of the PTR-LIT was demonstrated by distinguishing between the isomeric isoprene oxidation pair, methyl vinyl ketone (MVK) and methacrolein (MACR). The CID voltage was adjusted to maximize the m/ z 41 to 43 fragment ratio of MACR while still maintaining adequate sensitivity. Linear calibration curves for MVK and MACR fragments at m/ z 41 and 43 were obtained with limits of detection of approximately 100 ppt, which should enable ambient measurements. Finally, the PTR-LIT method was compared to an established GC/MS method by quantifying MVK and MACR production during a smog chamber isoprene-NO x irradiation experiment.

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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).
Link

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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