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Found 775 results
Title [ Year(Asc)]
2005
[1498] Holzinger, R.., A.. Lee, K.. T. Paw, and U.. A. H. Goldstein, "Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds", Atmospheric Chemistry and Physics, vol. 5, pp. 67–75, Jan, 2005.
Link: http://dx.doi.org/10.5194/acp-5-67-2005
Abstract
<p>Vertical gradients of mixing ratios of volatile organic compounds have been measured in a Ponderosa pine forest in Central California (38.90&deg; N, 120.63&deg; W, 1315m). These measurements reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13-66&micro;mol m-2h-1 to produce the observed oxidation products. That is 6-30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute a large fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.</p>
[1647] Jobson, B.T.., M.L.. Alexander, G.D.. Maupin, and G.G.. Muntean, "On-line analysis of organic compounds in diesel exhaust using a proton transfer reaction mass spectrometer (PTR-{MS})", International Journal of Mass Spectrometry, vol. 245, pp. 78–89, Aug, 2005.
Link: http://dx.doi.org/10.1016/j.ijms.2005.05.009
Abstract
Chemical ionization mass spectrometry using H3O+ proton transfer in an ion drift tube (PTR-MS) was used to measure volatile organic compound (VOC) concentrations on-line in diesel engine exhaust as a function of engine load. The purpose of the study was to evaluate the PTR-MS instrument as an analytical tool for diesel engine emissions abatement research. Measured sensitivities determined from gas standards were found to agree well with calculated sensitivities for non-polar species. A slight humidity dependent sensitivity was observed for non-polar species, implying that reactions with H+(H2O)2 were important for some organics. The diesel exhaust mass spectra were complex but displayed a pattern of strong ion signals at 14n + 1 (n = 3.8) masses, with a relative ion abundance similar to that obtained from electron impact ionization of alkanes. Laboratory experiments verified that C8–C16n-alkanes and C8–C13 1-alkenes react with H3O+ in dissociative proton transfer reaction resulting in alkyl cation ion products, primarily m/z 41, 43, 57, 71 and 85. Monitoring the sum of these ion signals may be useful for estimating alkane emissions from unburnt diesel fuel. Alkane fragmentation likely simplified the diesel exhaust mass spectrum and reduced potential mass interferences with isobaric aromatic compounds. Concentrations of aldehydes and ketones dominated those of aromatic species with formaldehyde and acetaldehyde estimated to be the most abundant VOCs in the PTR-MS mass spectrum at all engine loads. The relative abundances of benzene and toluene increased with engine load indicating their pyrogenic origin. The relative abundance of alkanes, aromatics, aldehydes and alcohols was broadly consistent with literature publications of diesel exhaust analysis by gas chromatography. About 75% of the organic ion signal could be assigned. On-line analysis of diesel exhaust using this technology may be valuable tool for diesel engine emission research.
[Ruuskanen2005] Ruuskanen, T. M., P. Kolari, J. Bäck, M. Kulmala, J. Rinne, H. Hakola, R. Taipale, M. Raivonen, N. Altimir, and P. Hari, "On-line field measurements of monoterpene emissions from Scots pine by proton-transfer-reaction mass spectrometry", Boreal environment research, vol. 10, no. 6, pp. 553–567, 2005.
Link: http://www.helsinki.fi/herc/research/URPOpublications/URPO_Ruuskanen%20et%20al%2005%5B1%5D.pdf
[Rinne2005] Rinne, J., T. M. Ruuskanen, A. Reissell, R. Taipale, H. Hakola, and M. Kulmala, "On-line PTR-MS measurements of atmospheric concentrations of volatile organic compounds in a European boreal forest ecosystem", Boreal environment research, vol. 10, no. 5, pp. 425–436, 2005.
Link: http://www.borenv.net/BER/pdfs/ber10/ber10-425.pdf
[Warneke2005] Warneke, C., S. Kato, J. A. { De Gouw}, P. D. Goldan, W. C. Kuster, M. Shao, E. R. Lovejoy, R. Fall, and F. C. Fehsenfeld, "Online volatile organic compound measurements using a newly developed proton-transfer ion-trap mass spectrometry instrument during New England Air Quality Study–Intercontinental Transport and Chemical Transformation 2004: performance, intercomparison, a", Environ Sci Technol, vol. 39, no. 14: National Oceanic and Atmospheric Administration, Aeronomy Laboratory, 325 Broadway, Boulder, Colorado 80305, USA. Carsten.Warneke@noaa.gov, pp. 5390–5397, Jul, 2005.
Link: http://pubs.acs.org/doi/abs/10.1021/es050602o
Abstract
We have used a newly developed proton-transfer ion-trap mass spectrometry (PIT-MS) instrument for online trace gas analysis of volatile organic compounds (VOCs) during the 2004 New England Air Quality Study-Intercontinental Transport and Chemical Transformation study. The PIT-MS instrument uses proton-transfer reactions with H3O+ ions to ionize VOCs, similarto a PTR-MS (proton-transfer reaction mass spectrometry) instrument but uses an ion trap mass spectrometer to analyze the product ions. The advantages of an ion trap are the improved identification of VOCs and a near 100% duty cycle. During the experiment, the PIT-MS instrument had a detection limit between 0.05 and 0.3 pbbv (S/N = 3 (signal-to-noise ratio)) for 2-min integration time for most tested VOCs. PIT-MS was used for ambient air measurements onboard a research ship and agreed well with a gas chromatography mass spectrometer). The comparison included oxygenated VOCs, aromatic compounds, and others such as isoprene, monoterpenes, acetonitrile, and dimethyl sulfide. Automated collision-induced dissociation measurements were used to determine the contributions of acetone and propanal to the measured signal at 59 amu; both species are detected at this mass and are thus indistinguishable in conventional PTR-MS.
[Beauchamp2005] Beauchamp, J., A. Wisthaler, A. Hansel, E. Kleist, M. Miebach, ÜLO. NIINEMETS, U. Schurr, and JÜRGEN. WILDT, "Ozone induced emissions of biogenic VOC from tobacco: relationships between ozone uptake and emission of LOX products", Plant, Cell & Environment, vol. 28, no. 10: Wiley Online Library, pp. 1334–1343, 2005.
Link: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2005.01383.x/full
Abstract
Volatile organic compound (VOC) emissions from tobacco (Nicotiana tabacum L. var. Bel W3) plants exposed to ozone (O3) were investigated using proton-transfer-reaction mass-spectrometry (PTR-MS) and gas chromatography mass-spectrometry (GC-MS) to find a quantitative reference for plants’ responses to O3 stress. O3 exposures to illuminated plants induced post-exposure VOC emission bursts. The lag time for the onset of volatile C6 emissions produced within the octadecanoid pathway was found to be inversely proportional to O3 uptake, or more precisely, to the O3 flux density into the plants. In cases of short O3 pulses of identical duration the total amount of these emitted C6 VOC was related to the O3 flux density into the plants, and not to ozone concentrations or dose–response relationships such as AOT 40 values. Approximately one C6 product was emitted per five O3 molecules taken up by the plant. A threshold flux density of O3 inducing emissions of C6 products was found to be (1.6 ± 0.7) × 10−8 mol m−2 s−1.
[Wisthaler2005] Wisthaler, A., G. Tamás, D. P. Wyon, P. Strøm-Tejsen, D. Space, J. Beauchamp, A. Hansel, T. D. Maerk, and C. J. Weschler, "Products of ozone-initiated chemistry in a simulated aircraft environment.", Environ Sci Technol, vol. 39, no. 13: International Centre for Indoor Environment and Energy, Technical University of Denmark (DTU), DK-2800 Kgs. Lyngby, Denmark., pp. 4823–4832, Jul, 2005.
Link: http://pubs.acs.org/doi/abs/10.1021/es047992j
Abstract
We used proton-transfer-reaction mass spectrometry (PTR-MS) to examine the products formed when ozone reacted with the materials in a simulated aircraft cabin, including a loaded high-efficiency particulate air (HEPA) filter in the return air system. Four conditions were examined: cabin (baseline), cabin plus ozone, cabin plus soiled T-shirts (surrogates for human occupants), and cabin plus soiled T-shirts plus ozone. The addition of ozone to the cabin without T-shirts, at concentrations typically encountered during commercial air travel, increased the mixing ratio (v:v concentration) of detected pollutants from 35 ppb to 80 ppb. Most of this increase was due to the production of saturated and unsaturated aldehydes and tentatively identified low-molecular-weight carboxylic acids. The addition of soiled T-shirts, with no ozone present, increased the mixing ratio of pollutants in the cabin air only slightly, whereas the combination of soiled T-shirts and ozone increased the mixing ratio of detected pollutants to 110 ppb, with more than 20 ppb originating from squalene oxidation products (acetone, 4-oxopentanal, and 6-methyl-5-hepten-2-one). For the two conditions with ozone present, the more-abundant oxidation products included acetone/propanal (8-20 ppb), formaldehyde (8-10 ppb), nonanal (approximately 6 ppb), 4-oxopentanal (3-7 ppb), acetic acid (approximately 7 ppb), formic acid (approximately 3 ppb), and 6-methyl-5-hepten-2-one (0.5-2.5 ppb), as well as compounds tentatively identified as acrolein (0.6-1 ppb) and crotonaldehyde (0.6-0.8 ppb). The odor thresholds of certain products were exceeded. With an outdoor air exchange of 3 h(-1) and a recirculation rate of 20 h(-1), the measured ozone surface removal rate constant was 6.3 h(-1) when T-shirts were not present, compared to 11.4 h(-1) when T-shirts were present.
[Biasioli2005] Biasioli, F., F. Gasperi, E. Aprea, D. Mott, I. Endrizzi, V. Framondino, and T. D. Märk, "PTR-MS in agroindustrial applications: a methodological perspective", Mass Spectrometry and Its Applications, pp. 77, 2005.
Link: http://www.uibk.ac.at/iup/infofolder/contributions_ptrms.pdf#page=88
[Zini2005] Zini, E., F. Biasioli, F. Gasperi, D. Mott, E. Aprea, T. D. Maerk, A. Patocchi, C. Gessler, and M. Komjanc, "QTL mapping of volatile compounds in ripe apples detected by proton transfer reaction-mass spectrometry", Euphytica, vol. 145, no. 3: Springer, pp. 269–279, 2005.
Link: http://www.springerlink.com/index/7353036TQ1852282.pdf
Abstract
The availability of genetic linkage maps enables the detection and analysis of QTLs contributing to quality traits of the genotype. Proton Transfer Reaction Mass Spectrometry (PTR-MS), a relatively novel spectrometric technique, has been applied to measure the headspace composition of the Volatile Organic Compounds (VOCs) emitted by apple fruit genotypes of the progeny ‘Fiesta’ × ‘Discovery’. Fruit samples were characterised by their PTR-MS spectra normalised to total area. QTL analysis for all PTR-MS peaks was carried out and 10 genomic regions associated with the peaks at m/z = 28, 43, 57, 61, 103, 115 and 145 were identified (LOD > 2.5). We show that it is possible to find quantitative trait loci (QTLs) related to PTR-MS characterisation of the headspace composition of single whole apple fruits indicating the presence of a link between molecular characterisation and PTR-MS data. We provide tentative information on the metabolites related to the detected QTLs based on available chemical information. A relation between apple skin colour and peaks related to carbonyl compounds was established.
[Karl2005] Karl, T., F. Harren, C. Warneke, J. De Gouw, C. Grayless, and R. Fall, "Senescing grass crops as regional sources of reactive volatile organic compounds", Journal of geophysical research, vol. 110, no. D15: American Geophysical Union, pp. D15302, 2005.
Link: http://www.agu.org/pubs/crossref/2005/2005JD005777.shtml
Abstract
Grass crop species, rice and sorghum, that are widely grown in the southeastern Texas region were analyzed for release of biogenic volatile organic compounds (VOCs) in simulated leaf-drying/senescence experiments. VOC release was measured by both online proton transfer reaction mass spectrometry (PTR-MS) and proton transfer ion trap mass spectrometry (PIT-MS) methods, and it was demonstrated that these two grass crops release a large variety of oxygenated VOCs upon drying under laboratory conditions primarily from leaves and not from stems. VOC release from paddy rice varieties was much greater than from sorghum, and major VOCs identified by gas chromatography PTR-MS included methanol, acetaldehyde, acetone, n-pentanal, methyl propanal, hexenol, hexanal, cis-3-hexenal, and trans-2-hexenal. The latter four VOCs, all C6 compounds known to be formed in wounded leaves, were the major volatiles released from drying rice leaves; smaller but substantial amounts of acetaldehyde were observed in all drying experiments. Online detection of VOCs using PIT-MS gave results comparable to those obtained with PTR-MS, and use of PIT-MS with collision-induced dissociation of trapped ions allowed unambiguous determination of the ratios of cis- and trans-hexenals during different phases of drying. As rice is one of the largest harvested crops on a global scale, it is conceivable that during rice senescence releases of biogenic VOCs, especially the reactive C6 wound VOCs, may contribute to an imbalance in regional atmospheric oxidant formation during peak summer/fall ozone formation periods. A county-by-county estimate of the integrated emissions of reactive biogenic VOCs from sorghum and rice production in Texas suggests that these releases are orders of magnitude lower than anthropogenic VOCs in urban areas but also that VOC emissions from rice in southeastern coastal Texas may need to be included in regional air quality assessments during periods of extensive harvesting.
[Gallardo-Escamilla2005] Gallardo-Escamilla, F.. J., A.. L. Kelly, and C.. M. Delahunty, "Sensory characteristics and related volatile flavor compound profiles of different types of whey.", J Dairy Sci, vol. 88, no. 8: Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland., pp. 2689–2699, Aug, 2005.
Link: http://dx.doi.org/10.3168/jds.S0022-0302(05)72947-7
Abstract
To characterize the flavor of liquid whey, 11 samples of whey representing a wide range of types were sourced from cheese and casein-making procedures, either industrial or from pilot-plant facilities. Whey samples were assessed for flavor by descriptive sensory evaluation and analyzed for headspace volatile composition by proton transfer reaction-mass spectrometry (PTR-MS). The sensory data clearly distinguished between the samples in relation to the processes of manufacture; that is, significant differences were apparent between cheese, rennet, and acid wheys. For Mozzarella and Quarg wheys, in which fermentation progressed to low pH values, the starter cultures used for cheese making had a significant influence on flavor. In comparison, Cheddar and Gouda wheys were described by milk-like flavors, and rennet casein wheys were described by "sweet" (oat-like and "sweet") and thermally induced flavors. The volatile compound data obtained by PTR-MS differentiated the samples as distinctive and reproducible "chemical fingerprints". On applying partial least squares regression to determine relationships between sensory and volatile composition data, sensory characteristics such as "rancid" and cheese-like odors and "caramelized milk," yogurt-like, "sweet," and oat-like flavors were found to be related to the presence and absence of specific volatile compounds.
[Lindinger2005] Lindinger, C., P. Pollien, S. Ali, C. Yeretzian, I. Blank, and T. Maerk, "Unambiguous identification of volatile organic compounds by proton-transfer reaction mass spectrometry coupled with GC/MS.", Anal Chem, vol. 77, no. 13: Nestlé Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland., pp. 4117–4124, Jul, 2005.
Link: http://pubs.acs.org/doi/abs/10.1021/ac0501240
Abstract
Interest in on-line measurements of volatile organic compounds (VOCs) is increasing, as sensitive, compact, and affordable direct inlet mass spectrometers are becoming available. Proton-transfer reaction mass spectrometry (PTR-MS) distinguishes itself by its high sensitivity (low ppt range), high time resolution (200 ms), little ionization-induced fragmentation, and ionization efficiency independent of the compound to be analyzed. Yet, PTR-MS has a shortcoming. It is a one-dimensional technique that characterizes compounds only via their mass, which is not sufficient for positive identification. Here, we introduce a technical and analytical extension of PTR-MS, which removes this shortcoming, while preserving its salient and unique features. Combining separation of VOCs by gas chromatography (GC) with simultaneous and parallel detection of the GC effluent by PTR-MS and electron impact MS, an unambiguous interpretation of complex PTR-MS spectra becomes feasible. This novel development is discussed on the basis of characteristic performance parameters, such as resolution, linear range, and detection limit. The recently developed drift tube with a reduced reaction volume is crucial to exploit the full potential of the setup. We illustrate the performance of the novel setup by analyzing a complex food system.
[Pinggera2005] Pinggera, G-M., P. Lirk, F. Bodogri, R. Herwig, G. Steckel-Berger, G. Bartsch, and J. Rieder, "Urinary acetonitrile concentrations correlate with recent smoking behaviour.", BJU Int, vol. 95, no. 3: Department of Urology, Medical University of Innsbruck, 6020 Innsbruck, Austria. Germar-Michael.Pinggera@uibk.ac.at, pp. 306–309, Feb, 2005.
Link: http://dx.doi.org/10.1111/j.1464-410X.2005.05288.x
Abstract
To assess the concentration of acetonitrile (a saturated aliphatic nitrile) in the urine of habitual cigarette smokers and non-smokers, as exposure to smoke can be measured by monitoring ambient air or by in vivo tests, but acetonitrile measured in exhaled breath is reportedly a quantitative marker of recent smoking behaviour.The study included 101 volunteers (57 men and 44 women, mean age 49 years). An absence of urinary tract infection on urine analysis or clinical history was mandatory. The subjects were classified into five groups, i.e. a control group of non-smokers and four groups according to the number of cigarettes smoked daily. Urine samples were stored at 8 degrees C until acetonitrile was measured, within 24 h of collection, using proton-transfer reaction mass spectrometry (PTR-MS). Each measurement was repeated at least 10 times, and the mean used for statistical analysis.The mean (sd) acetonitrile level in the urine of 46 non-smokers was 3.74 (1.78) parts per billion volatile (ppbv). The concentration of acetonitrile increased with the number of cigarettes smoked daily, the highest concentration being in the subgroup of 13 very heavy smokers (>30 cigarettes/day) with means up to 28.04 (5.38) ppbv.PTR-MS is a quick, noninvasive online method for determining urinary acetonitrile levels, a marker for recent active and passive smoking behaviour, and thus for checking compliance. As smoking has been shown to affect the genesis of bladder cancer, further studies are required to determine the association of acetonitrile with bladder cancer.
2004
[Biasioli2004a] Biasioli, F., F. Gasperi, G. Odorizzi, E. Aprea, and D. Mott, "Applicabilità del PTR-MS al controllo degli odori negli impianti per il trattamento dei rifiuti", Rifiuti solidi, 2004.
Link: http://openpub.iasma.it/handle/10449/18438
[Ammann2004] Ammann, C., C. Spirig, A. Neftel, M. Steinbacher, M. Komenda, and A. Schaub, "Application of PTR-MS for measurements of biogenic VOC in a deciduous forest", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 87–101, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003884
Abstract
The vegetation–atmosphere-exchange is an important process controlling the atmospheric concentration of various volatile organic compounds (VOCs) that play a major role in atmospheric chemistry. However, the quantification of VOC exchange on the ecosystem scale is still an analytical challenge. In the present study we tested and applied a proton-transfer-reaction mass spectrometry system (PTR-MS) for the measurement of biogenic VOCs in a mixed deciduous forest. VOC concentrations were calculated from the raw instrument signals based on physical principles. This method allows a consistent quantification also of compounds for which regular calibration with a gas standard is not available. It requires a regular and careful investigation of the mass-dependent ion detection characteristics of the PTR-MS, which otherwise could become a considerable error source. The PTR-MS method was tested in the laboratory for a range of oxygenated and non-oxygenated VOCs using a permeation source. The agreement was within 16% or better, which is well within the expected uncertainty. During the field measurement campaign in a deciduous forest stand, an on-line intercomparison with a state-of-the-art gas-chromatography system showed a generally good agreement. However, the relatively low ambient VOC concentrations revealed some systematic difference for acetone and isoprene, that may indicate an error in the determination of the PTR-MS offset or an interference of an unidentified isobaric compound on the detected ion mass. With the presentation of selected field results, we demonstrate the ability of the PTR-MS system to measure continuous vertical concentration profiles of biogenic VOCs throughout a forest canopy at a time resolution of 20 min. The resulting datasets provide valuable information for the study of the interactions between emission, photochemical transformation and transport processes within and above the forest canopy.
[Amann2004] Amann, A., G. Poupart, S. Telser, M. Ledochowski, A. Schmid, and S. Mechtcheriakov, "Applications of breath gas analysis in medicine", International Journal of Mass Spectrometry, vol. 239, no. 2-3, pp. 227 - 233, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003574
Abstract
Volatile organic compounds (VOCs) in exhaled breath gas provide valuable information about the subjects' physiological and pathophysiological condition. Proton-transfer-reaction mass spectrometry (PTR-MS) allows rapid and online measurements of these substances. We present results of three studies illustrating the potential of breath gas analysis by PTR-MS in various contexts: long-time online monitoring of VOCs in sleeping subjects suggests that VOC profiles are related to sleep stages. Analysis of VOC concentrations in the breath of carbohydrate malabsorbers emphasizes the role played by bacteria in the gut. Finally, we demonstrate the large intra- and intersubject concentration variability of VOCs by considering one particular mass.
[Cooper2004] Cooper, OR., C. Forster, D. Parrish, M. Trainer, E. Dunlea, T. Ryerson, G. Huebler, F. Fehsenfeld, D. Nicks, J. Holloway, et al., "A case study of transpacific warm conveyor belt transport: Influence of merging airstreams on trace gas import to North America", Journal of geophysical research, vol. 109, no. D23: American Geophysical Union, pp. D23S08, 2004.
Link: http://www.agu.org/pubs/crossref/2004/2003JD003624.shtml
Abstract
The warm conveyor belt (WCB), the major cloud-forming airstream of midlatitude cyclones, is the primary mechanism for rapidly transporting air pollution from one continent to another. However, relatively little has been written on WCB transport across the North Pacific Ocean. To address this important intercontinental transport route, this study describes the life cycle of a WCB associated with the export of a highly polluted air mass from Asia to North America. This event was sampled using in situ measurements from an aircraft platform flying above the North American West Coast during the 2002 Intercontinental Transport and Chemical Transformation (ITCT 2K2) experiment on 5 May. Satellite imagery, trajectory ensembles, in situ measurements, and animations are used to illustrate the formation of the WCB near eastern Asia, its entrainment of polluted air masses, its transport path across the Pacific, and its decay above the eastern North Pacific Ocean and western North America. A major finding is that a WCB can entrain air from a variety of source regions and not just the atmospheric boundary layer. We estimate that 8% of the WCB's mass originated in the stratosphere and 44% passed through the lower troposphere, of which two thirds passed through the lower troposphere above the populated regions of eastern Asia. The remaining 48% traveled entirely within the middle and upper troposphere over the previous 5.5 days. Interestingly, an estimated 18% of the WCB's mass was entrained from an upwind and decaying WCB via a newly discovered but apparently common transport mechanism. Only 9% of the WCB's mass subsequently passed through the lower troposphere of the United States, with the remainder passing over North America in the middle and upper troposphere.
[Biasioli2004b] Biasioli, F., F. Gasperi, D. Mott, E. Aprea, F. Marini, and TD. Maerk, "Characterization of Strawberry Genotypes by PTR-MS Spectral Fingerprinting: a Three Year Study", V International Strawberry Symposium 708, pp. 497–500, 2004.
Link: http://www.actahort.org/books/708/708_87.htm
Abstract
Proton Transfer Reaction Mass Spectrometry (PTR-MS) fingerprinting has been used to accurately and rapidly identify the cultivar of single intact strawberry fruits. The technique has been applied in a 3-cultivar experiment with 70 fruits harvested in 2002, 2003 and 2004. The proposed models correctly predicted the cultivar. Cross-validation tests verified 100% correct classification. The data indicated the possibility of correctly characterizing single fruit by fast non-invasive measurements without any pre-treatment and/or concentration of the headspace gas mixture. This is a necessary preliminary step in view of correlation studies of PTR-MS data with genetics and other characterization of fruits, in particular, sensory analysis. Extension to more cultivars is envisaged.
[Boscaini2004] Boscaini, E., T. Mikoviny, A. Wisthaler, E. von Hartungen, and T. D. Märk, "Characterization of wine with PTR-MS", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 215–219, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003537
Abstract
A new method for measuring volatile profiles of alcoholic beverages (or other ethanol-containing analytes such as perfumes or herbs) has been developed. The method is based on proton transfer reaction mass spectrometry (PTR-MS). However, instead of hydronium ions (H3O+) protonated ethanol clusters (C2H5OH2+(C2H5OH)n = 1,2) are used as chemical ionization reagent ions. A stable reagent ion distribution is obtained by a 10-fold dilution of analyte headspace into ethanol-saturated nitrogen. Samples with different ethanol content can thus be directly compared. Characteristic mass spectral fingerprints have been obtained for four wine varieties. Principal component analysis discriminates between different wine varieties and shows specific correlations between wine variety and selected ions.
[Christian2004] Christian, TJ., B. Kleiss, RJ. Yokelson, R. Holzinger, PJ. Crutzen, WM. Hao, T. Shirai, and DR. Blake, "Comprehensive laboratory measurements of biomass-burning emissions: 2. First intercomparison of open-path FTIR, PTR-MS, and GC-MS/FID/ECD", Journal of geophysical research, vol. 109, no. D2: American Geophysical Union, pp. D02311, 2004.
Link: http://www.agu.org/pubs/crossref/2004/2003JD003874.shtml
Abstract
Oxygenated volatile organic compounds (OVOC) can dominate atmospheric organic chemistry, but they are difficult to measure reliably at low levels in complex mixtures. Several techniques that have been used to speciate nonmethane organic compounds (NMOC) including OVOC were codeployed/intercompared in well-mixed smoke generated by 47 fires in the U.S. Department of Agriculture Forest Service Fire Sciences Combustion Facility. The agreement between proton transfer reaction mass spectrometry (PTR-MS) and open-path Fourier transform infrared spectroscopy (OP-FTIR) was excellent for methanol (PT/FT = 1.04 ± 0.118) and good on average for phenol (0.843 ± 0.845) and acetol (∼0.81). The sum of OP-FTIR mixing ratios for acetic acid and glycolaldehyde agreed (within experimental uncertainty) with the PTR-MS mixing ratios for protonated mass 61 (PT/FT = 1.17 ± 0.34), and the sum of OP-FTIR mixing ratios for furan and isoprene agreed with the PTR-MS mixing ratios for protonated mass 69 (PT/FT = 0.783 ± 0.465). The sum of OP-FTIR mixing ratios for acetone and methylvinylether accounted for most of the PTR-MS protonated mass 59 signal (PT/FT = 1.29 ± 0.81), suggesting that one of these compounds was underestimated by OP-FTIR or that it failed to detect other compounds that could contribute at mass 59. Canister grab sampling followed by gas chromatography (GC) with mass spectrometry (MS), flame ionization detection (FID), and electron capture detection (ECD) analysis by two different groups agreed well with OP-FTIR for ethylene, acetylene, and propylene. However, these propylene levels were below those observed by PTR-MS (PT/FT = 2.33 ± 0.89). Good average agreement between PTR-MS and GC was obtained for benzene and toluene. At mixing ratios above a few parts per billion the OP-FTIR had advantages for measuring sticky compounds (e.g., ammonia and formic acid) or compounds with low proton affinity (e.g., hydrogen cyanide and formaldehyde). Even at these levels, only the PTR-MS measured acetonitrile and acetaldehyde. Below a few ppbv only the PTR-MS measured a variety of OVOC, but the possibility of fragmentation, interference, and sampling losses must be considered.
[Schnitzler2004] SCHNITZLER, JÖRG-PETER., M. Graus, J. Kreuzwieser, U. Heizmann, H. Rennenberg, A. Wisthaler, and A. Hansel, "Contribution of different carbon sources to isoprene biosynthesis in poplar leaves", Plant Physiology, vol. 135, no. 1: Am Soc Plant Biol, pp. 152–160, 2004.
Link: http://www.plantphysiol.org/content/135/1/152.short
Abstract
This study was performed to test if alternative carbon sources besides recently photosynthetically fixed CO2 are used for isoprene formation in the leaves of young poplar (Populus × canescens) trees. In a 13CO2 atmosphere under steady state conditions, only about 75% of isoprene became 13C labeled within minutes. A considerable part of the unlabeled carbon may be derived from xylem transported carbohydrates, as may be shown by feeding leaves with [U-13C]Glc. As a consequence of this treatment approximately 8% to 10% of the carbon emitted as isoprene was 13C labeled. In order to identify further carbon sources, poplar leaves were depleted of leaf internal carbon pools and the carbon pools were refilled with 13C labeled carbon by exposure to 13CO2. Results from this treatment showed that about 30% of isoprene carbon became 13C labeled, clearly suggesting that, in addition to xylem transported carbon and CO2, leaf internal carbon pools, e.g. starch, are used for isoprene formation. This use was even increased when net assimilation was reduced, for example by abscisic acid application. The data provide clear evidence of a dynamic exchange of carbon between different cellular precursors for isoprene biosynthesis, and an increasing importance of these alternative carbon pools under conditions of limited photosynthesis. Feeding [1,2-13C]Glc and [3-13C]Glc to leaves via the xylem suggested that alternative carbon sources are probably derived from cytosolic pyruvate/phosphoenolpyruvate equivalents and incorporated into isoprene according to the predicted cleavage of the 3-C position of pyruvate during the initial step of the plastidic deoxyxylulose-5-phosphate pathway.
[LaPorta2004] La Porta, N., F. Biasioli, F. Gasperi, and T. D. Märk, "Discrimination of Heterobasidion annosum ISGs by evaluation of volatile organic compounds", S. Michele all'Adige, Italy, vol. 27, no. 8, pp. 379–382, 2004.
Link: http://core.kmi.open.ac.uk/download/pdf/2835560#page=418
Abstract
Heterobasidion annosum represents one of the most dangerous fungi in the conifer forest of the boreal hemisphere. This fungus was differentiated into three biological species (Intersterile groups; ISGs) characterized by different host specificity, patogenicity and distribution. A fast and easy identification of the ISG has important consequences on the silvicultural decition making. However, the determination of the ISG from the morphological traits of fruit bodies or, least of all, from mycelium is usually not easy. Proton Transfer Reaction – Mass Spectrometry (PTR-MS) is a new technique proposed and realised by the University of Innsbruck, and now issued also to the market. This technique allows high performance on-line measurements for a large number of VOCs. The aim of this work was to verify the possibility to discriminate the H. annosum ISGs based on their volatile compound emission and to identify putative characteristic masses that may play an important role in the host specificity and in the specific antagonistic fungi among each ISGs. Twelve strains belong to the three ISGs (here idicated by F, P and S) were analysed by PTRMS fingerprinting. P ISG was definitely separated from F and S ISGs. In addition, several masses show to be significantly different among the three ISGs. ANOVA on PTR-MS peak values identified 16 significant masses out of 230. Applications and limitations of this approach are discussed.
[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.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003914
Abstract
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.
[Jaksch2004] Jaksch, D., R. Margesin, T. Mikoviny, JD. Skalny, E. Hartungen, F. Schinner, NJ. Mason, and TD. Märk, "The effect of ozone treatment on the microbial contamination of pork meat measured by detecting the emissions using PTR-MS and by enumeration of microorganisms", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 209–214, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003471
Abstract
In this paper, we report the results of treating commercial samples of pork meat with ozone in order to determine whether such treatment reduces microbial growth and hence extends the shelf lifetime of such products. The technique of Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) was used to study volatile emissions with the signal detected at mass 63 (assumed to be a measure for dimethylsulphide) being used as a diagnostic of bacterial activity. Such a signal was found to strongly increase with time for an untreated meat sample whereas ozone-treated meat samples showed much reduced emissions—suggesting that the microbial activity had been greatly suppressed by ozone treatment. An independent analysis, however, revealed that microbial counts were very high, independent of the treatment.
[Tani2004] Tani, A., S. Hayward, A. Hansel, and N. C Hewitt, "Effect of water vapour pressure on monoterpene measurements using proton transfer reaction-mass spectrometry (PTR-MS)", International Journal of Mass Spectrometry, vol. 239, no. 2: Elsevier, pp. 161–169, 2004.
Link: http://www.sciencedirect.com/science/article/pii/S1387380604003495
Abstract
The effects of water vapour pressure (WVP) on the fragmentation of seven monoterpene and related C10 volatile organic compounds (VOCs) in the drift tube of a proton transfer reaction-mass spectrometer (PTR-MS) were investigated. In addition, the combined effects of varying WVP and the ratios of electric field strength to number density of the buffer gas (E/N) were investigated in detail for three of these compounds, the monoterpenes α-pinene and sabinene plus the related C10 VOC p-cymene. Under normal operating conditions (E/N = 124 Td), WVP affected the fragment patterns of all compounds with the exception of β-pinene and the three oxygenated C10 VOCs. WVP had a significant effect on the fragment patterns of α-pinene and sabinene at the lower E/N ratios (around 80 Td) but had little effect on fragmentation towards the higher E/N ratios used here (∼142 Td). On the other hand, p-cymene fragmentation was most affected by WVP under normal operating conditions. PTR-MS sensitivity towards the three compounds was also considered under three conditions where reaction was assumed with (1) H3O+ only; (2) H3O+ and H3O+H2O; and (3) H3O+, H3O+H2O and H3O+(H2O)2. Our results indicate that α-pinene and sabinene react not only with H3O+ and H3O+H2O via direct proton transfer but also with H3O+(H2O)2 via ligand switching. p-Cymene seems to react only with H3O+ via direct proton transfer and with H3O+H2O via ligand switching. It is speculated that the WVP effect on fragmentation results from the differing abundances of hydrated reagent ions which causes different frequencies of individual reactions to occur, thus, determining how ‘soft’ the overall reaction is. These results also indicate that under normal conditions, a correction should be made for WVP if the concentration of p-cymene in air samples is to be determined from the single ion signal of either protonated molecular ions or the most dominant fragment ions.

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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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