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Found 19 results
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2015
[1627] Sahu, L.K.., and P. Saxena, "High time and mass resolved PTR-TOF-MS measurements of VOCs at an urban site of India during winter: Role of anthropogenic, biomass burning, biogenic and photochemical sources", Atmospheric Research, vol. 164-165, pp. 84–94, Oct, 2015.
Link: http://dx.doi.org/10.1016/j.atmosres.2015.04.021
Abstract
<p>This study is based on the high mass and time-resolved measurements of seven VOCs using a PTR-TOF-MS instrument at an urban site of India during winter 2013. Daily levels of OVOCs and aromatics were in the ranges of 3.5&ndash;37 ppbv and 0.85&ndash;23 ppbv, respectively with OVOCs accounted for up to 80% of total measured VOCs. The impact of long-range transport from the polluted Indo-Gangetic Plain and clean Thar desert was observed during the episodes of high and low VOCs, respectively. VOCs exhibited strong diurnal variations with peaks during morning and evening hours and lowest in the afternoon. Relatively elevated aromatics during evening hours coincided with the lowest-OVOCs indicating influence of fresh vehicular emissions. Emission ratios of isoprene and OVOCs with respect to benzene followed the diurnal cycles of temperature and solar flux indicating role of biogenic and photochemical processes, respectively. Correlation study of VOCs with benzene suggests major contribution from anthropogenic and also from biogenic and secondary sources to some extent. The higher emission ratios of ∆methanol/∆acetonitrile correspond to the episodes of long-range transport from biomass burning sources located in the Indo-Gangetic Plain (IGP). In addition to the pattern of emission, the diurnal and day-to-day variations of VOCs were influenced by the local meteorological conditions and depth of planetary boundary layer (PBL).</p>
2014
[1642] W Acton, J., M. Lanza, B. Agarwal, S. Jürschik, P. Sulzer, K. Breiev, A. Jordan, E. Hartungen, G. Hanel, L. Märk, et al., "Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer.", Int J Mass Spectrom, vol. 360, pp. 28–38, Mar, 2014.
Link: http://dx.doi.org/10.1016/j.ijms.2013.12.009
Abstract
<p>The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O(+), O2 (+), NO(+) and Kr(+) with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios.</p>
2013
[1467] W. Acton, J., M. Lanza, B. Agarwal, S. Jürschik, P. Sulzer, K. Breiev, A. Jordan, E. Hartungen, G. Hanel, L. Märk, et al., "Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer", International Journal of Mass Spectrometry, pp. -, 2013.
Link: http://www.sciencedirect.com/science/article/pii/S1387380613004454
Abstract
<p>The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O+, O2+, NO+ and Kr+ with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios.</p>
[1695] Slade, J. H., and D. A. Knopf, "Heterogeneous OH oxidation of biomass burning organic aerosol surrogate compounds: assessment of volatilisation products and the role of OH concentration on the reactive uptake kinetics.", Phys Chem Chem Phys, vol. 15, pp. 5898–5915, Apr, 2013.
Link: http://dx.doi.org/10.1039/c3cp44695f
Abstract
<p>The reactive uptake coefficients (γ) of OH by levoglucosan, abietic acid, and nitroguaiacol serving as surrogate compounds for biomass burning aerosol have been determined employing a chemical ionisation mass spectrometer coupled to a rotating-wall flow-tube reactor over a wide range of [OH] &sim;10(7)-10(11) molecule cm(-3). Volatilisation products of these organic substrates due to heterogeneous oxidation by OH have been determined at 1 atm using a high resolution proton transfer reaction time-of-flight mass spectrometer (HR-PTR-ToF-MS). γ range within 0.05-1 for [OH] = 2.6 &times; 10(7)-3 &times; 10(9) molecule cm(-3) for all investigated organic compounds, but decrease to 0.008-0.034 for [OH] = 4.1 &times; 10(10)-6.7 &times; 10(10) molecule cm(-3). γ as a function of [OH] can be described by a Langmuir-Hinshelwood model, neglecting bulk processes, suggesting that despite its strong reactivity, OH is mobile on surfaces prior to reaction. The best fit Langmuir-Hinshelwood parameters on average are K(OH) = 3.81 &times; 10(-10) cm(3) molecule(-1) and k(s) = 9.71 &times; 10(-17) cm(2) molecule(-1) s(-1) for all of the investigated organic compounds. Volatilised products have been identified indicating enhancements over background of 50% up to a factor of 15. Amongst the common volatile organic compounds (VOCs) identified between levoglucosan, abietic acid, and nitroguaiacol were methanol, acetaldehyde, formic acid, and acetic acid. VOCs having the greatest enhancement over background were glucic acid from levoglucosan, glycolic acid from abietic acid, and methanol and nitric acid from nitroguaiacol. Reaction mechanisms leading to the formation of glucic acid, glycolic acid, methanol, and nitric acid are proposed. Estimated lower limits of atmospheric lifetimes of biomass burning aerosol particles, 200 nm in diameter, by heterogeneous OH oxidation under fresh biomass burning plume conditions are &sim;2 days and up to &sim;2 weeks for atmospheric background conditions. However, estimated lifetimes depend crucially on [OH] and corresponding γ, emphasising the need to determine γ under relevant conditions.</p>
[Romano2013] Romano, A., L. Cappellin, V. Ting, E. Aprea, L. Navarini, M. Barnabà, F. Gasperi, and F. Biasioli, "Hyphenation of PTR-ToF-MS and newly developed software provides a new effective tool for the study of inter-individual differences among tasters", CONFERENCE SERIES, pp. 59, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
2012
[Halbritter2012] Halbritter, S.., M.. Fedrigo, V.. Hoellriegl, W.. Szymczak, J.. M. Maier, A.. Ziegler, and M.. Hummel, "Human Breath Gas Analysis in the Screening of Gestational Diabetes Mellitus", DIABETES TECHNOLOGY & THERAPEUTICS, vol. 14, pp. 10, 2012.
Link: http://dx.doi.org/10.1089/dia.2012.0076
Abstract
{Background: We present a pilot study on the feasibility of the application and advantages of online, noninvasive breath gas analysis (BGA) by proton transfer reaction quadrupole mass spectrometry for the screening of gestational diabetes mellitus (GDM) in 52 pregnant women by means of an oral glucose tolerance test (OGTT). Subjects and Methods: We collected and identified samples of end-tidal breath gas from patients during OGTT. Time evolution parameters of challenge-responsive volatile organic compounds (VOCs) in human breath gas were estimated. Multivariate analysis of variance and permutation analysis were used to assess feasibility of BGA as a diagnostic tool for GDM. Results: Standard OGTT diagnosis identified pregnant women as having GDM (n = 8), impaired glucose tolerance (n = 12), and normal glucose tolerance (n = 32); a part of this latter group was further subdivided into a ''marginal'' group (n = 9) because of a marginal high 1-h or 2-h OGTT value. We observed that OGTT diagnosis (four metabolic groups) could be mapped into breath gas data. The time evolution of oxidation products of glucose and lipids, acetone metabolites, and thiols in breath gas after a glucose challenge was correlated with GDM diagnosis (P = 0.035). Furthermore, basal (fasting) values of dimethyl sulfide and values of methanol in breath gas were inversely correlated with phenotype characteristics such as homeostasis model assessment of insulin resistance index (R= -0.538; P = 0.0002
2011
[Brunner2011] Brunner, C.., W.. Szymczak, W.. Li, C. Hoeschen, S.. Moertl, F.. Eckardt-Schupp, and U. Oeh, "Headspace measurements of irradiated in vitro cultured cells using PTR-MS.", Radiat Environ Biophys, vol. 50, no. 1: Department of Medical Radiation Physics and Diagnostics, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany. claudia.brunner@helmholtz-muenchen.de, pp. 209–217, Mar, 2011.
Link: http://dx.doi.org/10.1007/s00411-010-0327-8
Abstract
A pilot study was performed to evaluate a new concept for a radiation biodosimetry method. Proton transfer reaction-mass spectrometry (PTR-MS) was used to find out whether radiation induces changes in the composition of volatile organic compounds (VOCs) in the headspace of in vitro cultured cells. Two different cell lines, retinal pigment epithelium cells hTERT-RPE1 and lung epithelium cells A-549, were irradiated with gamma radiation at doses of 4 Gy and 8 Gy. For measuring the cell-specific effects, the VOC concentrations in the headspace of flasks containing cells plus medium, as well as of flasks containing pure medium were analyzed for changes before and after irradiation. No significant radiation-induced alterations in VOC concentrations in the headspace could be observed after irradiation.
2010
[Jordan2010a] Jordan, A., S. Jaksch, S. Juerschik, A. Edtbauer, B. Agarwal, G. Hanel, E. Hartungen, H. Seehauser, L. Märk, P. Sulzer, et al., "H3O+, NO+ and O2 as precursor ions in PTR as precursor ions in PTR-MS: isomeric VOC compounds and reactions with different chemical groups", : IONICON Analytik, 2010.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/poster_ionicon_dgms_sri.pdf
[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.
[Kameyama2010] Kameyama, S., H. Tanimoto, S. Inomata, U. Tsunogai, A. Ooki, S. Takeda, H. Obata, A. Tsuda, and M. Uematsu, "High-resolution measurement of multiple volatile organic compounds dissolved in seawater using equilibrator inlet–proton transfer reaction-mass spectrometry (EI–PTR-MS)", Marine Chemistry, vol. 122, no. 1: Elsevier, pp. 59–73, 2010.
Link: http://www.sciencedirect.com/science/article/pii/S0304420310000939
Abstract
We developed an equilibrator inlet–proton transfer reaction-mass spectrometry (EI–PTR-MS) system for high-resolution measurement of the concentrations of multiple volatile organic compounds (VOCs) dissolved in seawater. The equilibration of five VOCs (isoprene, propene, acetone, acetaldehyde, and methanol) between seawater samples and the carrier gas, and the response time of the system, were evaluated by means of a series of laboratory experiments. Although equilibrium between the seawater sample and the carrier gas in the equilibrator was not achieved for isoprene and propene (likely because of their low water solubility), the other species did reach equilibrium. The EI–PTR-MS system was deployed during a research cruise in the western North Pacific Ocean. Evaluation of several seawater sampling methods indicated that there was no significant contamination from the sampling apparatus for the target VOCs. For isoprene, comparison of EI–PTR-MS measurements with measurements obtained with a membrane equilibrator–gas chromatography/mass spectrometry system showed generally good agreement (R2 = 0.79). EI–PTR-MS captured the temporal variations of dissolved VOCs, including small-scale variability, which demonstrates that the performance of the EI–PTR-MS system was sufficient for simultaneous and continuous measurements of multiple VOCs of environmental importance in seawater.
[Demarcke2010] Demarcke, M., J-F. Müller, N. Schoon, H. Van Langenhove, J. Dewulf, E. Joó, K. Steppe, M. Šimpraga, B. Heinesch, M. Aubinet, et al., "History effect of light and temperature on monoterpenoid emissions from Fagus sylvatica L.", Atmospheric Environment, vol. 44, no. 27: Elsevier, pp. 3261–3268, 2010.
Link: http://www.sciencedirect.com/science/article/pii/S1352231010004462
Abstract
Monoterpenoid emissions from Fagus sylvatica L. trees have been measured at light- and temperature-controlled conditions in a growth chamber, using Proton Transfer Reaction Mass Spectrometry (PTR-MS) and the dynamic branch enclosure technique. De novo synthesized monoterpenoid Standard Emission Factors, obtained by applying the G97 algorithm (Guenther, 1997), varied between 2 and 32 μg gDW−1 h−1 and showed a strong decline in late August and September, probably due to senescence. The response of monoterpenoid emissions to temperature variations at a constant daily light pattern could be well reproduced with a modified version of the MEGAN algorithm (Guenther et al., 2006), with a typical dependence on the average temperature over the past five days. The diurnal emissions at constant temperature showed a typical hysteretic behaviour, which could also be adequately described with the modified MEGAN algorithm by taking into account a dependence on the average light levels experienced by the trees during the past 10–13 h. The impact of the past light and temperature conditions on the monoterpenoid emissions from F. sylvatica L. was found to be much stronger than assumed in previous algorithms. Since our experiments were conducted under low light intensity, future studies should aim at confirming and completing the proposed algorithm updates in sunny conditions and natural environments.
[Tomsheck2010] Tomsheck, A. R., G. A. Strobel, E. Booth, B. Geary, D. Spakowicz, B. Knighton, C. Floerchinger, J. Sears, O. Liarzi, and D. Ezra, "Hypoxylon sp., an endophyte of Persea indica, producing 1, 8-cineole and other bioactive volatiles with fuel potential", Microbial ecology, vol. 60, no. 4: Springer, pp. 903–914, 2010.
Link: http://link.springer.com/article/10.1007/s00248-010-9759-6
Abstract
An endophytic fungus of Persea indica was identified, on the basis of its anamorphic stage, as Nodulosporium sp. by SEM. Partial sequence analysis of ITS rDNA revealed the identity of the teleomorphic stage of the fungus as Hypoxylon sp. It produces an impressive spectrum of volatile organic compounds (VOCs), most notably 1,8-cineole, 1-methyl-1,4-cyclohexadiene, and tentatively identified (+)-.alpha.-methylene-.alpha.-fenchocamphorone, among many others, most of which are unidentified. Six-day-old cultures of Hypoxylon sp. displayed maximal VOC-antimicrobial activity against Botrytis cinerea, Phytophthora cinnamomi, Cercospora beticola, and Sclerotinia sclerotiorum suggesting that the VOCs may play some role in the biology of the fungus and its survival in its host plant. Media containing starch- or sugar-related substrates best supported VOC production by the fungus. Direct on-line quantification of VOCs was measured by proton transfer mass spectrometry covering a continuous range with optimum VOC production occurred at 6 days at 145 ppmv with a rate of production of 7.65 ppmv/h. This report unequivocally demonstrates that 1,8-cineole (a monoterpene) is produced by a microorganism, which represents a novel and important source of this compound. This monoterpene is an octane derivative and has potential use as a fuel additive as do the other VOCs of this organism. Thus, fungal sourcing of this compound and other VOCs as produced by Hypoxylon sp. greatly expands their potential applications in medicine, industry, and energy production.
2009
[Knighton2009] Knighton, WB., EC. Fortner, A. J. Midey, AA. Viggiano, SC. Herndon, EC. Wood, and CE. Kolb, "HCN detection with a proton transfer reaction mass spectrometer", International Journal of Mass Spectrometry, vol. 283, no. 1: Elsevier, pp. 112–121, 2009.
Link: http://www.sciencedirect.com/science/article/pii/S1387380609000712
Abstract
Proton transfer reaction mass spectrometry (PTR-MS) is a promising technique for making rapid, sensitive measurements of HCN in the atmosphere. However, because the proton affinity of HCN is only slightly greater than that of water, the reverse proton transfer reaction of protonated HCN with water is important and the PTR-MS response to HCN is temperature and humidity dependent. The instrument response of a PTR-MS was calibrated at a variety of HCN mixing ratios, temperatures and relative humidities. A simple model with a kinetic and thermodynamic basis was developed to fit these results and accurately accounted for the temperature and humidity dependence of these measurements. Reaction rate coefficients were determined using a selected ion flow tube mass spectrometer (SIFT). Changes in sensitivity due to variations in temperature and humidity were simply and accurately corrected for using measurable parameters, including the H3O+(H2O) to H3O+ ratio as a measure of the water vapor concentration along with an empirically determined temperature and pressure correction factor. This calibration procedure should be applicable to the quantification of other compounds possessing proton affinities similar to that of HCN such as formaldehyde and hydrogen sulfide. The technique was applied during a two-week ambient measurement period. Analysis of that data suggests that ethene is a spectral interferent. The ethene interference arises due to the presence of O2+, which is generated as an unwanted byproduct as a result of using a low-pressure hollow cathode discharge as an external ion source. O2+ reacts with ethene via charge transfer reaction to form C2H4+, which has the same mass-to-charge ratio as protonated HCN. The magnitude of the ethene interference is estimated at 0.1 ppbv HCN equivalent per ppbv of ethene. The ethene interference can be controlled through reducing or eliminating the amount of O2+. HCN concentrations deduced from the ambient measurements after correction for the ethene interference appear reasonable and provide evidence that PTR-MS instruments can be employed for the measurement of HCN.
[Jordan2009b] Jordan, A., S. Haidacher, G. Hanel, E. Hartungen, L. Maerk, H. Seehauser, R. Schottkowsky, P. Sulzer, and TD. Maerk, "A high resolution and high sensitivity proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS)", International Journal of Mass Spectrometry, vol. 286, no. 2: Elsevier, pp. 122–128, 2009.
Link: http://www.sciencedirect.com/science/article/pii/S1387380609002371
Abstract
Proton-transfer-reaction mass spectrometry (PTR-MS) developed about 10 years ago is used today in a wide range of scientific and technical fields allowing real-time on-line measurements of volatile organic compounds in air with a high sensitivity and a fast response time. Most instruments employed so far use quadrupole filters to analyze product ions generated in the reaction drift tube. Due to the low mass resolution of the quadrupoles used this has the disadvantage that identification of trace gases under study is not unambiguous. Here we report the development of a new version of PTR-MS instruments using a time-of-flight mass spectrometer, which is capable of measuring VOCs at ultra-low concentrations (as low as a few pptv) under high mass resolution (as high as 6000 m/Δm in the V-mode) with a mass range of beyond 100 000 amu. This instrument was constructed by interfacing the well characterized and recently improved Ionicon hollow cathode ion source and drift tube section with a Tofwerk orthogonal acceleration reflectron time-of-flight mass spectrometer. We will first discuss the set-up of this new PTR-TOF-MS mass spectrometer instrument, its performance (with a sensitivity of several tens of cps/ppbv) and finally give some examples concerning urban air measurements where sensitivity, detection limit and mass resolution is essential to obtain relevant data.
2006
[Herndon2006] Herndon, S. C., T. Rogers, E. J. Dunlea, J. T. Jayne, R. Miake-Lye, and B. Knighton, "Hydrocarbon emissions from in-use commercial aircraft during airport operations.", Environ Sci Technol, vol. 40, no. 14: Aerodyne Research, Inc., Billerica, Massachusetts, USA. herndon@aerodyne.com, pp. 4406–4413, Jul, 2006.
Link: http://pubs.acs.org/doi/abs/10.1021/es051209l
Abstract
The emissions of selected hydrocarbons from in-use commercial aircraft at a major airport in the United States were characterized using proton-transfer reaction mass spectrometry (PTR-MS) and tunable infrared differential absorption spectroscopy (TILDAS) to probe the composition of diluted exhaust plumes downwind. The emission indices for formaldehyde, acetaldehyde, benzene, and toluene, as well as other hydrocarbon species, were determined through analysis of 45 intercepted plumes identified as being associated with specific aircraft. As would have been predicted for high bypass turbine engines, the hydrocarbon emission index was greater in idle and taxiway acceleration plumes relative to approach and takeoff plumes. The opposite was seen in total NOy emission index, which increased from idle to takeoff. Within the idle plumes sampled in this study, the median emission index for formaldehyde was 1.1 g of HCHO per kg of fuel. For the subset of hydrocarbons measured in this work, the idle emissions levels relative to formaldehyde agree well with those of previous studies. The projected total unburned hydrocarbons (UHC) deduced from the range of in-use idle plumes analyzed in this work is greater than a plausible range of engine types using the defined idle condition (7% of rated engine thrust) in the International Civil Aviation Organization (ICAO) databank reference.
[1499] Varutbangkul, V.., F.. J. Brechtel, R.. Bahreini, N.. L. Ng, M.. D. Keywood, J.. H. Kroll, R.. C. Flagan, J.. H. Seinfeld, A.. Lee, and A.. H. Goldstein, "Hygroscopicity of secondary organic aerosols formed by oxidation of cycloalkenes, monoterpenes, sesquiterpenes, and related compounds", Atmospheric Chemistry and Physics, vol. 6, pp. 2367–2388, Jun, 2006.
Link: http://nature.berkeley.edu/ahg/pubs/Hygroscopicity.pdf
Abstract
<p>A series of experiments has been conducted in the Caltech indoor smog chamber facility to investigate the water uptake properties of aerosol formed by oxidation of various organic precursors. Secondary organic aerosol (SOA) from simple and substituted cycloalkenes (C5-C8) is produced in dark ozonolysis experiments in a dry chamber (RH&nbsp;5%). Biogenic SOA from monoterpenes, sesquiterpenes, and oxygenated terpenes is formed by photooxidation in a humid chamber (&nbsp;50% RH). Using the hygroscopicity tandem differential mobility analyzer (HTDMA), we measure the diameter-based hygroscopic growth factor (GF) of the SOA as a function of time and relative humidity. All SOA studied is found to be slightly hygroscopic, with smaller water uptake than that of typical inorganic aerosol substances. The aerosol water uptake increases with time early in the experiments for the cycloalkene SOA, but decreases with time for the sesquiterpene SOA. This behavior could indicate competing effects between the formation of more highly oxidized polar compounds (more hygroscopic), and formation of longer-chained oligomers (less hygroscopic). All SOA also exhibit a smooth water uptake with RH with no deliquescence or efflorescence. The water uptake curves are found to be fitted well with an empirical three-parameter functional form. The measured pure organic GF values at 85% RH are between 1.09&ndash;1.16 for SOA from ozonolysis of cycloalkenes, 1.01&ndash;1.04 for sesquiterpene photooxidation SOA, and 1.06&ndash;1.10 for the monoterpene and oxygenated terpene SOA. The GF of pure SOA (GForg) in experiments in which inorganic seed aerosol is used is determined by assuming volume-weighted water uptake (Zdanovskii-Stokes-Robinson or &quot;ZSR&quot; approach) and using the size-resolved organic mass fraction measured by the Aerodyne Aerosol Mass Spectrometer. Knowing the water content associated with the inorganic fraction yields GForg values. However, for each precursor, the GForg values computed from different HTDMA-classified diameters agree with each other to varying degrees. Comparing growth factors from different precursors, we find that GForg is inversely proportional to the precursor molecular weight and SOA yield, which is likely a result of the fact that higher-molecular weight precursors tend to produce larger and less hygroscopic oxidation products.</p>
2001
[Poeschl2001] Pöschl, U., J. Williams, P. Hoor, H. Fischer, PJ. Crutzen, C. Warneke, R. Holzinger, A. Hansel, A. Jordan, W. Lindinger, et al., "High acetone concentrations throughout the 0–12 km altitude range over the tropical rainforest in Surinam", Journal of atmospheric chemistry, vol. 38, no. 2: Springer, pp. 115–132, 2001.
Link: http://link.springer.com/article/10.1023/A:1006370600615
[Karl2001] Karl, T., P. Prazeller, D. Mayr, A. Jordan, J. Rieder, R. Fall, and W. Lindinger, "Human breath isoprene and its relation to blood cholesterol levels: new measurements and modeling", Journal of Applied Physiology, vol. 91, no. 2, pp. 762-770, 2001.
Link: http://jap.physiology.org/content/91/2/762.abstract
Abstract
Numerous publications have described measurements of breath isoprene in humans, and there has been a hope that breath isoprene analyses could be a noninvasive diagnostic tool to assess blood cholesterol levels or cholesterol synthesis rate. However, significant analytic problems in breath isoprene analysis and variability in isoprene levels with age, exercise, diet, etc., have limited the usefulness of these measurements. Here, we have applied proton transfer reaction-mass spectrometry to this problem, allowing on-line detection of breath isoprene. We show that breath isoprene concentration increases within a few seconds after exercise is started as a result of a rapid increase in heart rate and then reaches a lower steady state when breath rate stabilizes. Additional experiments demonstrated that increases in heart rate associated with standing after reclining or sleeping are associated with increased breath isoprene concentrations. An isoprene gas-exchange model was developed and shows excellent fit to breath isoprene levels measured during exercise. In a preliminary experiment, we demonstrated that atorvastatin therapy leads to a decrease in serum cholesterol and low-density-lipoprotein levels and a parallel decrease in breath isoprene levels. This work suggests that there is constant endogenous production of isoprene during the day and night and reaffirms the possibility that breath isoprene can be a noninvasive marker of cholesterologenesis if care is taken to measure breath isoprene under standard conditions at constant heart rate.
2000
[Crutzen2000] Crutzen, PJ., J. Williams, U. Poeschl, P. Hoor, H. Fischer, C. Warneke, R. Holzinger, A. Hansel, W. Lindinger, B. Scheeren, et al., "High spatial and temporal resolution measurements of primary organics and their oxidation products over the tropical forests of Surinam", Atmospheric environment, vol. 34, no. 8: Elsevier, pp. 1161–1165, 2000.
Link: http://www.sciencedirect.com/science/article/pii/S1352231099004823
Abstract
Tropical forests with emissions greater than 1015 g C of reactive hydrocarbons per year strongly affect atmospheric chemistry. Here we report aircraft-borne measurements of organics during March 1998 in Surinam, a largely unpolluted region which is optimally located to study chemical processes induced by tropical forest emissions. Isoprene and its degradation products methylvinyl ketone (MVK) and methacrolein (MACR) and possibly isoprene hydroperoxides (ISOHP), were measured in the nmol mol−1 volume mixing ratio (VMR) range, consistent with estimated emissions and model calculations. In addition, high VMRs of some non-isoprene-derived organics were measured, such as acetone (≈2–4 nmol mol1 up to 12 km altitude), an important source of HO and HO2 in the upper troposphere. Moreover, several masses were measured at significant mixing ratios which could not be identified by reference to previous field measurements or gas-phase isoprene chemistry. High VMRs, almost 0.4 nmol mol−1, were also recorded for a compound which is most likely dimethyl sulphide (DMS). If so, boundary layer loss of HO by reactions with hydrocarbons and their oxidation products strongly prolongs the lifetime of DMS, allowing its transport deep into the Amazon forest south of the intertropical convergence zone (ITCZ). We postulate greater sulphate production and deposition north than south of the (ITCZ) with possible consequences for cloud and ecosystem properties.

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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.
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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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