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Scientific Articles - PTR-MS Bibliography

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Found 62 results
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2017
[1770] Hatch, L. E., R. J. Yokelson, C. E. Stockwell, P. R. Veres, I. J. Simpson, D. R. Blake, J. J. Orlando, and K. C. Barsanti, "Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors", Atmospheric Chemistry and Physics, vol. 17, pp. 1471–1489, Jan, 2017.
Link: http://dx.doi.org/10.5194/acp-17-1471-2017
Abstract
<p>Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography&ndash;time-of-flight mass spectrometry (GC&thinsp;&times;&thinsp;GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was also deployed, as well as whole-air sampling (WAS) with one-dimensional gas chromatography&ndash;mass spectrometry (GC-MS) analysis. This combination of instruments provided an unprecedented level of detection and chemical speciation. The chemical composition and emission factors (EFs) determined by these four analytical techniques were compared for four representative fuels. The results demonstrate that the instruments are highly complementary, with each covering some unique and important ranges of compositional space, thus demonstrating the need for multi-instrument approaches to adequately characterize BB smoke emissions. Emission factors for overlapping compounds generally compared within experimental uncertainty, despite some outliers, including monoterpenes. Data from all measurements were synthesized into a single EF database that includes over 500 non-methane organic gases (NMOGs) to provide a comprehensive picture of speciated, gaseous BB emissions. The identified compounds were assessed as a function of volatility; 6&ndash;11 % of the total NMOG EF was associated with intermediate-volatility organic compounds (IVOCs). These atmospherically relevant compounds historically have been unresolved in BB smoke measurements and thus are largely missing from emission inventories. Additionally, the identified compounds were screened for published secondary organic aerosol (SOA) yields. Of the total reactive carbon (defined as EF scaled by the OH rate constant and carbon number of each compound) in the BB emissions, 55&ndash;77 % was associated with compounds for which SOA yields are unknown or understudied. The best candidates for future smog chamber experiments were identified based on the relative abundance and ubiquity of the understudied compounds, and they included furfural, 2-methyl furan, 2-furan methanol, and 1,3-cyclopentadiene. Laboratory study of these compounds will facilitate future modeling efforts.</p>
2016
[1764] Morozova, K., A. Romano, F. Lonardi, R. Ferrarini, F. Biasioli, and M. Scampicchio, "Microcalorimetric monitoring of grape withering", Thermochimica Acta, vol. 630, pp. 31–36, Apr, 2016.
Link: http://dx.doi.org/10.1016/j.tca.2016.01.011
Abstract
<p>tThis work aimed at monitoring the metabolic activity of grapes during withering by microcalorimetry.Samples of Corvina grapes, a cultivar used in the production of Amarone wine, were dehydrated for about120 days at an industrial scale plants (fruttaia). Single berries, sampled in the course of the witheringprocess, were closed in ampoules and maintained at constant temperature. As biochemical events (i.e.berry respiration, microbial growth, etc.) are always accompanied by the production of heat (q), the heat-flow (dq/dt) emitted by berries enclosed in the ampoules was used to monitor their metabolic activityduring withering, i.e. respiration. For each sampling time, the heat rate production of the berries at 298 Kwas monitored till a steady state signal was achieved (within 60 h). Such heat flow value was used asmarker during the entire withering process (120 days). Its trend allowed to characterize the changesin the metabolic activity of the grape berries along the withering process. To understand the origin ofsuch changes, the emission of volatile organic compounds (VOCs) were also measured by proton transfermass spectrometry (PTR-MS). The use of microcalorimetry associated with the analysis of specific VOCsfragments offered a valuable information to describe the withering process.</p>
[1738] Hansen, M. J., K. E. N. Jonassen, M. Marie Lokke, A. Peter S. Adamsen, and A. Feilberg, "Multivariate prediction of odor from pig production based on in-situ measurement of odorants", Atmospheric Environment, vol. 135, pp. 50–58, Jun, 2016.
Link: http://dx.doi.org/10.1016/j.atmosenv.2016.03.060
Abstract
<p>The aim of the present study was to estimate a prediction model for odor from pig production facilities based on measurements of odorants by Proton-Transfer-Reaction Mass spectrometry (PTR-MS). Odor measurements were performed at four different pig production facilities with and without odor abatement technologies using a newly developed mobile odor laboratory equipped with a PTR-MS for measuring odorants and an olfactometer for measuring the odor concentration by human panelists. A total of 115 odor measurements were carried out in the mobile laboratory and simultaneously air samples were collected in Nalophan bags and analyzed at accredited laboratories after 24 h. The dataset was divided into a calibration dataset containing 94 samples and a validation dataset containing 21 samples. The prediction model based on the measurements in the mobile laboratory was able to explain 74% of the variation in the odor concentration based on odorants, whereas the prediction models based on odor measurements with bag samples explained only 46&ndash;57%. This study is the first application of direct field olfactometry to livestock odor and emphasizes the importance of avoiding any bias from sample storage in studies of odor-odorant relationships. Application of the model on the validation dataset gave a high correlation between predicted and measured odor concentration (R2 = 0.77). Significant odorants in the prediction models include phenols and indoles. In conclusion, measurements of odorants on-site in pig production facilities is an alternative to dynamic olfactometry that can be applied for measuring odor from pig houses and the effects of odor abatement technologies.</p>
2015
[1623] Baasandorj, M.., D.. B. Millet, L.. Hu, D.. Mitroo, and B.. J. Williams, "Measuring acetic and formic acid by proton-transfer-reaction mass spectrometry: sensitivity, humidity dependence, and quantifying interferences", Atmos. Meas. Tech., vol. 8, pp. 1303–1321, 2015.
Link: http://dx.doi.org/10.5194/amt-8-1303-2015
Abstract
We present a detailed investigation of the factors governing the quantification of formic acid (FA), acetic acid (AA), and their relevant mass analogues by proton-transfer-reaction mass spectrometry (PTR-MS), assess the underlying fragmentation pathways and humidity dependencies, and present a new method for separating FA and AA from their main isobaric interferences. PTR-MS sensitivities towards glycolaldehyde, ethyl acetate, and peroxyacetic acid at m/z 61 are comparable to that for AA; when present, these species will interfere with ambient AA measurements by PTR-MS. Likewise, when it is present, dimethyl ether can interfere with FA measurements. For a reduced electric field (E/N) of 125 Townsend (Td), the PTR-MS sensitivity towards ethanol at m/z 47 is 5–20 times lower than for FA; ethanol will then only be an important interference when present in much higher abundance than FA. Sensitivity towards 2-propanol is <1% of that for AA, so that propanols will not in general represent a significant interference for AA. Hydrated product ions of AA, glycolaldehyde, and propanols occur at m/z 79, which is also commonly used to measure benzene. However, the resulting interference for benzene is only significant when E/N is low (<= 100 Td). Addition of water vapor affects the PTR-MS response to a given compound by (i) changing the yield for fragmentation reactions and (ii) increasing the importance of ligand switching reactions. In the case of AA, sensitivity to the molecular ion increases with humidity at low E/N but decreases with humidity at high E/N due to water-driven fragmentation. Sensitivity towards FA decreases with humidity throughout the full range of E/N. For glycolaldehyde and the alcohols, the sensitivity increases with humidity due to ligand switching reactions (at low E/N) and reduced fragmentation in the presence of water (at high E/N). Their role as interferences will typically be greatest at high humidity. For compounds such as AA where the humidity effect depends strongly on the collisional energy in the drift tube, simple humidity correction factors (XR) will only be relevant for a specific instrumental configuration. We recommend E/N   125 Td as an effective condition for AA and FA measurements by PTR-MS, as it optimizes between the competing E/N-dependent mechanisms controlling their sensitivities and those of the interfering species. Finally, we present the design and evaluation of an online acid trap for separating AA and FA from their interfering species at m/z 61 and 47, and we demonstrate its performance during a field deployment to St. Louis, USA, during August–September of 2013.
[1679] Hayeck, N., B. Temime-Roussel, S. Gligorovski, A. Mizzi, R. Gemayel, S. Tlili, P. Maillot, N. Pic, T. Vitrani, I. Poulet, et al., "Monitoring of organic contamination in the ambient air of microelectronic clean room by proton-transfer reaction/time-of-flight/mass spectrometry (PTR-ToF-MS)", International Journal of Mass Spectrometry, Oct, 2015.
Link: http://dx.doi.org/10.1016/j.ijms.2015.09.017
Abstract
<p>The organic contamination has been recently considered as the most important problem for the photolithography world in the semiconductor industry, especially when the photolithographic methods moved from 130 nm node to 32 nm node. One of the most common organic compounds found in photolithography areas of the clean room is Trimethylsilanol (TMS), which can adsorb on the optical lenses forming a thin molecular layer, hence causing damages. Salt crystal formation is another potential threat for the optical devices. In the clean rooms, this salt is produced by a light-induced reaction between ammonia and an acid. In the context of semiconductor industry, the involved acid is usually the acetic acid produced by hydrolysis from propylene glycol methyl ether acetate (PGMEA), a commonly used organic compound in the photolithography. Here, we present an innovative analytical method using a state-of-the-art proton-transfer reaction&ndash;time-of-flight&ndash;mass spectrometer (PTR&ndash;ToF&ndash;MS) for on-line and continuous survey of volatile organic compounds (VOCs) with an emphasis on TMS and PGMEA. The effect of relative humidity on the detection and fragmentation of these organic compounds was assessed. The new analytical method is operated in a real life clean room environment and the results were compared with those obtained with off-line measurements using automated thermal desorber&ndash;gas chromatography&ndash;mass spectrometry (ATD&ndash;GC&ndash;MS) as reference method. The contamination sources were detected and identified, which is of paramount importance for the microelectronic fabrication plant. The trapping efficiency of the chemical filters used for AMCs filtration in the photolithography zone was determined.</p>
[1711] Materic, D., M. Lanza, P. Sulzer, J. Herbig, D. Bruhn, C. Turner, N. Mason, and V. Gauci, "Monoterpene separation by coupling proton transfer reaction time-of-flight mass spectrometry with fastGC.", Anal Bioanal Chem, vol. 407, pp. 7757–7763, Oct, 2015.
Link: http://dx.doi.org/10.1007/s00216-015-8942-5
Abstract
<p>Proton transfer reaction mass spectrometry (PTR-MS) is a well-established technique for real-time analysis of volatile organic compounds (VOCs). Although it is extremely sensitive (with sensitivities of up to 4500 cps/ppbv, limits of detection &lt;1 pptv and the response times of approximately 100 ms), the selectivity of PTR-MS is still somewhat limited, as isomers cannot be separated. Recently, selectivity-enhancing measures, such as manipulation of drift tube parameters (reduced electric field strength) and using primary ions other than H3O(+), such as NO(+) and O2 (+), have been introduced. However, monoterpenes, which belong to the most important plant VOCs, still cannot be distinguished so more traditional technologies, such as gas chromatography mass spectrometry (GC-MS), have to be utilised. GC-MS is very time consuming (up to 1 h) and cannot be used for real-time analysis. Here, we introduce a sensitive, near-to-real-time method for plant monoterpene research-PTR-MS coupled with fastGC. We successfully separated and identified six of the most abundant monoterpenes in plant studies (α- and β-pinenes, limonene, 3-carene, camphene and myrcene) in less than 80 s, using both standards and conifer branch enclosures (Norway spruce, Scots pine and black pine). Five monoterpenes usually present in Norway spruce samples with a high abundance were separated even when the compound concentrations were diluted to 20 ppbv. Thus, fastGC-PTR-ToF-MS was shown to be an adequate one-instrument solution for plant monoterpene research.</p>
[1655] Materic, D., M. Lanza, P. Sulzer, J. Herbig, D. Bruhn, C. Turner, N. Mason, and V. Gauci, "Monoterpene separation by coupling proton transfer reaction time-of-flight mass spectrometry with fastGC", Analytical and Bioanalytical Chemistry, Aug, 2015.
Link: http://dx.doi.org/10.1007/s00216-015-8942-5
Abstract
<p>Proton transfer reaction mass spectrometry (PTR-MS) is a well-established technique for real-time analysis of volatile organic compounds (VOCs). Although it is extremely sensitive (with sensitivities of up to 4500 cps/ppbv, limits of detection &lt;1 pptv and the response times of approximately 100 ms), the selectivity of PTR-MS is still somewhat limited, as isomers cannot be separated. Recently, selectivity-enhancing measures, such as manipulation of drift tube parameters (reduced electric field strength) and using primary ions other than H3O+, such as NO+ and O2 +, have been introduced. However, monoterpenes, which belong to the most important plant VOCs, still cannot be distinguished so more traditional technologies, such as gas chromatography mass spectrometry (GC-MS), have to be utilised. GC-MS is very time consuming (up to 1 h) and cannot be used for real-time analysis. Here, we introduce a sensitive, near-to-real-time method for plant monoterpene research&mdash;PTR-MS coupled with fastGC. We successfully separated and identified six of the most abundant monoterpenes in plant studies (α- and β-pinenes, limonene, 3-carene, camphene and myrcene) in less than 80 s, using both standards and conifer branch enclosures (Norway spruce, Scots pine and black pine). Five monoterpenes usually present in Norway spruce samples with a high abundance were separated even when the compound concentrations were diluted to 20 ppbv. Thus, fastGC-PTR-ToF-MS was shown to be an adequate one-instrument solution for plant monoterpene research.</p>
2014
[1564] Smith, D., P. Spanel, J. Herbig, and J. Beauchamp, "Mass spectrometry for real-time quantitative breath analysis", Journal of Breath Research, vol. 8, pp. 027101, Mar, 2014.
Link: http://dx.doi.org/10.1088/1752-7155/8/2/027101
Abstract
<p>Breath analysis research is being successfully pursued using a variety of analytical methods, prominent amongst which are gas chromatography with mass spectrometry, GC-MS, ion mobility spectrometry, IMS, and the fast flow and flow-drift tube techniques called selected ion flow tube mass spectrometry, SIFT-MS, and proton transfer reaction mass spectrometry, PTR-MS. In this paper the case is made for real-time breath analysis by obviating sample collection into bags or onto traps that can suffer from partial degradation of breath metabolites or the introduction of impurities. Real-time analysis of a broad range of volatile chemical compounds can be best achieved using SIFT-MS and PTR-MS, which are sufficiently sensitive and rapid to allow the simultaneous analyses of several trace gas metabolites in single breath exhalations. The basic principles and the ion chemistry that underpin these two analytical techniques are briefly described and the differences between them, including their respective strengths and weaknesses, are revealed, especially with reference to the analysis of the complex matrix that is exhaled breath. A recent innovation is described that combines time-of-flight mass spectrometry with the proton transfer flow-drift tube reactor, PTR-TOFMS, which provides greater resolution in the analytical mass spectrometer and allows separation of protonated isobaric molecules. Examples are presented of some recent data that well illustrate the quality and real-time feature of SIFT-MS and PTR-MS for the analysis of exhaled breath for physiological/biochemical/pharmacokinetics studies and for the identification and quantification of biomarkers relating to specific disease states.</p>
[1602] Smith, D., P. Spanel, J. Herbig, and J. Beauchamp, "Mass spectrometry for real-time quantitative breath analysis.", J Breath Res, vol. 8, pp. 027101, Jun, 2014.
Link: http://dx.doi.org/10.1088/1752-7155/8/2/027101
Abstract
<p>Breath analysis research is being successfully pursued using a variety of analytical methods, prominent amongst which are gas chromatography with mass spectrometry, GC-MS, ion mobility spectrometry, IMS, and the fast flow and flow-drift tube techniques called selected ion flow tube mass spectrometry, SIFT-MS, and proton transfer reaction mass spectrometry, PTR-MS. In this paper the case is made for real-time breath analysis by obviating sample collection into bags or onto traps that can suffer from partial degradation of breath metabolites or the introduction of impurities. Real-time analysis of a broad range of volatile chemical compounds can be best achieved using SIFT-MS and PTR-MS, which are sufficiently sensitive and rapid to allow the simultaneous analyses of several trace gas metabolites in single breath exhalations. The basic principles and the ion chemistry that underpin these two analytical techniques are briefly described and the differences between them, including their respective strengths and weaknesses, are revealed, especially with reference to the analysis of the complex matrix that is exhaled breath. A recent innovation is described that combines time-of-flight mass spectrometry with the proton transfer flow-drift tube reactor, PTR-TOFMS, which provides greater resolution in the analytical mass spectrometer and allows separation of protonated isobaric molecules. Examples are presented of some recent data that well illustrate the quality and real-time feature of SIFT-MS and PTR-MS for the analysis of exhaled breath for physiological/biochemical/pharmacokinetics studies and for the identification and quantification of biomarkers relating to specific disease states.</p>
[1596] Tanimoto, H., S. Kameyama, T. Iwata, S. Inomata, and Y. Omori, "Measurement of air-sea exchange of dimethyl sulfide and acetone by PTR-MS coupled with gradient flux technique.", Environ Sci Technol, vol. 48, pp. 526–533, Jan, 2014.
Link: http://dx.doi.org/10.1021/es4032562
Abstract
<p>We developed a new method for in situ measurement of air-sea fluxes of multiple volatile organic compounds (VOCs) by combining proton transfer reaction-mass spectrometry (PTR-MS) and gradient flux (GF) technique. The PTR-MS/GF system was first deployed to determine the air-sea flux of VOCs in the open ocean of the western Pacific, in addition to carbon dioxide and water vapor. Each profiling at seven heights from the ocean surface up to 14 m took 7 min. In total, 34 vertical profiles of VOCs in the marine atmosphere just above the ocean surface were obtained. The vertical gradient observed was significant for dimethyl sulfide (DMS) and acetone with the best-fit curves on quasi-logarithmic relationship. The mean fluxes of DMS and acetone were 5.5 &plusmn; 1.5 and 2.7 &plusmn; 1.3 μmol/m(2)/day, respectively. These fluxes are in general in accordance with those reported by previous expeditions.</p>
[1563] Silcock, P.., M.. Alothman, E.. Zardin, S.. Heenan, C.. Siefarth, P.J.. Bremer, and J.. Beauchamp, "Microbially induced changes in the volatile constituents of fresh chilled pasteurised milk during storage", Food Packaging and Shelf Life, vol. 2, pp. 81¬タモ90, Dec, 2014.
Link: http://dx.doi.org/10.1016/j.fpsl.2014.08.002
Abstract
<p>Off-odours caused by volatile organic compounds (VOCs) are often the first indicators consumers have of milk spoilage. In this study the VOCs associated with three types (trim, 0.25&ndash;0.40% fat; lite, 1.40&ndash;1.50% fat; and full-cream, 3.18&ndash;3.28% fat) of fresh chilled pasteurised milk (FCPM), held for up to 17 days at 4.5 &plusmn; 0.5 &deg;C, were measured using proton-transfer-reaction mass spectrometry (PTR-MS). The chemical identification of VOCs in the headspace of the milk was supported by SPME&ndash;GC&ndash;MS analysis. Bacterial numbers (aerobic plate count at 25 &deg;C) in the milk were also estimated. Replicate sets of milk types treated with sodium azide (NaN3) to inhibit microbial activity were investigated. The relationship between microbial numbers and VOCs was not linear; rather the concentrations of VOCs only started to change after a threshold number of bacteria ranging from 106&ndash;108 CFU mL&minus;1 was reached. This combined approach provided new insights on the effect of microbial growth on FCPM shelf-life.</p>
[1561] Beauchamp, J., E. Zardin, P. Silcock, and P. J. Bremer, "Monitoring photooxidation-induced dynamic changes in the volatile composition of extended shelf life bovine milk by PTR-{MS}", Journal of Mass Spectrometry, vol. 49, pp. 952–958, Sep, 2014.
Link: http://dx.doi.org/10.1002/jms.3430
Abstract
<p>Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf life (ESL) bovine milk samples were exposed to fluorescent light for up to 20 h at room temperature, and the volatiles in the samples&#39; headspace were measured in real time using proton-transfer-reaction mass spectrometry (PTR-MS). Compounds tentatively identified as methanethiol, acetone/propanal, pentanal/octanal/nonanal/1-octen-3-ol, hexanal, diacetyl, dimethyl disulphide, heptanal and benzaldehyde displayed dynamic release profiles relating to the changes occurring in milk upon exposure to light. Copyright &copy; 2014 John Wiley &amp; Sons, Ltd.</p>
2013
[1466] Sarkar, C., V. Kumar, and V. Sinha, "Massive emissions of carcinogenic benzenoids from paddy residue burning in North India", Current Science, vol. 104, pp. 1703-1709, 2013.
Link: http://www.currentscience.ac.in/Volumes/104/12/1703.pdf
Abstract
<p>Benzenoids are organic pollutants emitted mainly by traffic and industrial sources. Here, using a combination of on-line in situ PTR-MS measurements of several benzenoids and methyl cyanide (a biomassburning tracer), satellite remote sensing data of fire counts and back trajectory of air masses at a site in Mohali, we show that massive amounts of benzenoids are released from post-harvest paddy residue burning. Two periods, one that was not influenced by paddy residue burning (period 1, 18 : 00&ndash;03 : 30 IST; 5&ndash;6 October 2012) and another which was strongly influenced by paddy residue burning (period 2, 18 : 00&ndash; 03 : 30 IST; 3&ndash;4 November 2012) were chosen to assess normal and perturbed levels. Peak values of 3830 ppb CO, 100 ppb NOx, 40 ppb toluene, 16 ppb benzene, 24 ppb for sum of all C-8 benzenoids and 13 ppb for sum of all C-9 benzenoids were observed during period 2 (number of measurements in period 2 = 570) with the average enhancements in benzenoid levels being more than 300%. The ozone formation potential of benzenoids matched that of CO, with both contributing 5 ppb/h each. Such high levels of benzenoids for 1&ndash;2 months in a year aggravate smog events and can enhance cancer risks in northwestern India.</p>
[Feilberg2013] Feilberg, A., D. Liu, and M. Jørgen Hansen, "Measurement of H2S by PTR-MS: Experiences and implications", CONFERENCE SERIES, pp. 98, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
[Pleil2013] Pleil, J. D., W. Miekisch, T. H. Risby, M. C. Madden, and J. R. Sobus, "Meeting reports for 2013: recent advances in breath biomarker research", Journal of breath research, vol. 7, no. 2: IOP Publishing, pp. 029001, 2013.
Link: http://iopscience.iop.org/1752-7163/7/2/029001
[1457] Beale, R., J. L. Dixon, S. R. Arnold, P. S. Liss, and P. D. Nightingale, "Methanol, acetaldehyde, and acetone in the surface waters of the Atlantic Ocean", Journal of Geophysical Research: Oceans, vol. 118, pp. 5412–5425, 2013.
Link: http://dx.doi.org/10.1002/jgrc.20322
Abstract
<p>Oceanic methanol, acetaldehyde, and acetone concentrations were measured during an Atlantic Meridional Transect (AMT) cruise from the UK to Chile (49&deg;N to 39&deg;S) in 2009. Methanol (48&ndash;361 nM) and acetone (2&ndash;24 nM) varied over the track with enrichment in the oligotrophic Northern Atlantic Gyre. Acetaldehyde showed less variability (3&ndash;9 nM) over the full extent of the transect. These oxygenated volatile organic compounds (OVOCs) were also measured subsurface, with methanol and acetaldehyde mostly showing homogeneity throughout the water column. Acetone displayed a reduction below the mixed layer. OVOC concentrations did not consistently correlate with primary production or chlorophyll-a levels in the surface Atlantic Ocean. However, we did find a novel and significant negative relationship between acetone concentration and bacterial leucine incorporation, suggesting that acetone might be removed by marine bacteria as a source of carbon. Microbial turnover of both acetone and acetaldehyde was confirmed. Modeled atmospheric data are used to estimate the likely air-side OVOC concentrations. The direction and magnitude of air-sea fluxes vary for all three OVOCs depending on location. We present evidence that the ocean may exhibit regions of acetaldehyde under-saturation. Extrapolation suggests that the Atlantic Ocean represents an overall source of these OVOCs to the atmosphere at 3, 3, and 1 Tg yr&minus;1 for methanol, acetaldehyde, and acetone, respectively.</p>
[Fischer2013] Fischer, L., V. Ruzsanyi, K. Winkler, R. Gutmann, A. Hansel, and J. Herbig, "Micro-Capillary-Column PTR-TOF", 6th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications, pp. 162, 2013.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/contributions_ptr_ms_Conference_6.pdf
[Tsevdou2013] Tsevdou, M., C. Soukoulis, L. Cappellin, F. Gasperi, P. S. Taoukis, and F. Biasioli, "Monitoring the effect of high pressure and transglutaminase treatment of milk on the evolution of flavour compounds during lactic acid fermentation using PTR-ToF-MS.", Food Chem, vol. 138, no. 4: Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens, Polytechnioupoli Zografou, Zografou 15780, Athens, Greece., pp. 2159–2167, Jun, 2013.
Link: http://dx.doi.org/10.1016/j.foodchem.2012.12.007
Abstract
In this study, the effects of thermal or high hydrostatic pressure (HHP) treatment of a milk base in the absence or presence of a transglutaminase (TGase) protein cross-linking step on the flavour development of yoghurt were investigated. The presence of several tentatively identified volatile flavour compounds (VOCs), both during the enzymatic treatment and the lactic acid fermentation of the milk base, were monitored using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). The formation of the major flavour compounds (acetaldehyde, diacetyl, acetoin, and 2-butanone) followed a sigmoidal trend described by the modified Gompertz model. The HHP treatment of milk increased significantly the volatile compound formation rate whereas it did not affect the duration of the lag phase of formation, with the exception of acetaldehyde and diacetyl formation. On the contrary, the TGase cross-linking of milk did not significantly modify the formation rate of the volatile compounds but shortened the duration of the lag phase of their formation.
[1445] Ruzsanyi, V., L. Fischer, J. Herbig, C. Ager, and A. Amann, "Multi-capillary-column proton-transfer-reaction time-of-flight mass spectrometry.", J Chromatogr A, vol. 1316, pp. 112–118, Nov, 2013.
Link: http://dx.doi.org/10.1016/j.chroma.2013.09.072
Abstract
<p>Proton-transfer-reaction time-of-flight mass-spectrometry (PTR-TOFMS) exhibits high selectivity with a resolution of around 5000m/Δm. While isobars can be separated with this resolution, discrimination of isomeric compounds is usually not possible. The coupling of a multi-capillary column (MCC) with a PTR-TOFMS overcomes these problems as demonstrated in this paper for the ketone isomers 3-heptanone and 2-methyl-3-hexanone and for different aldehydes. Moreover, fragmentation of compounds can be studied in detail which might even improve the identification. LODs for compounds tested are in the range of low ppbv and peak positions of the respective separated substances show good repeatability (RSD of the peak positions &lt;3.2%). Due to its special characteristics, such as isothermal operation, compact size, the MCC setup is suitable to be installed inside the instrument and the overall retention time for a complete spectrum is only a few minutes: this allows near real-time measurements in the optional MCC mode. In contrast to other methods that yield additional separation, such as the use of pre-cursor ions other than H3O(+), this method yields additional information without increasing complexity.</p>
[Cappellin2013a] Cappellin, L., E. Aprea, P. Granitto, A. Romano, F. Gasperi, and F. Biasioli, "Multiclass methods in the analysis of metabolomic datasets: The example of raspberry cultivar volatile compounds detected by GC-MS and PTR-MS", Food Research International: Elsevier, 2013.
Link: http://www.sciencedirect.com/science/article/pii/S0963996913000975
Abstract
Multiclass sample classification and marker selection are cutting-edge problems in metabolomics. In the present study we address the classification of 14 raspberry cultivars having different levels of gray mold (Botrytis cinerea) susceptibility. We characterized raspberry cultivars by two headspace analysis methods, namely solid-phase microextraction/gas chromatography–mass spectrometry (SPME/GC–MS) and proton transfer reaction-mass spectrometry (PTR-MS). Given the high number of classes, advanced data mining methods are necessary. Random Forest (RF), Penalized Discriminant Analysis (PDA), Discriminant Partial Least Squares (dPLS) and Support Vector Machine (SVM) have been employed for cultivar classification and Random Forest-Recursive Feature Elimination (RF-RFE) has been used to perform feature selection. In particular the most important GC–MS and PTR-MS variables related to gray mold susceptibility of the selected raspberry cultivars have been investigated. Moving from GC–MS profiling to the more rapid and less invasive PTR-MS fingerprinting leads to a cultivar characterization which is still related to the corresponding Botrytis susceptibility level and therefore marker identification is still possible.
[Holopainen2013] Holopainen, J. K., A-M. Nerg, and J. D. Blande, "Multitrophic signalling in polluted atmospheres", Biology, controls and models of tree volatile organic compound emissions: Springer, pp. 285–314, 2013.
Link: http://link.springer.com/chapter/10.1007/978-94-007-6606-8_11
Abstract
Volatile compounds emitted by plants in response to herbivory serve as important cues within and between trophic levels, and as cues over more than two trophic levels, such as in the attraction of enemies of herbivores. However, many of the volatiles elicited by herbivory are highly reactive with key atmospheric pollutants, implying that the signal is communicated over increasingly shorter distances with increasing pollutant concentrations in the atmosphere. Thus, polluted atmospheres can importantly alter the multitrophic interactions between trees, herbivores and herbivore enemies. This chapter highlights the alterations in multitrophic interactions and resulting modifications in plant fitness in polluted atmospheres.
2012
[Andersen2012] Andersen, K. Barkve, M. J. Ã. ¸rgen Hansen, and A. Feilberg, "Minimisation of artefact formation of dimethyl disulphide during sampling and analysis of methanethiol in air using solid sorbent materials.", J Chromatogr A, vol. 1245: Applied Plasma Physics AS, Bedriftsveien 25, PO Box 584, 4305 Sandnes, Norway., pp. 24–31, Jul, 2012.
Link: http://dx.doi.org/10.1016/j.chroma.2012.05.020
Abstract
Methanethiol (MT) is a potent odorant that can be difficult to measure due to its high volatility and reactivity; it easily reacts to form dimethyl disulphide (DMDS) during sampling and/or analysis. This paper focuses on finding an optimal method for sampling and measuring MT with minimum artefact formation using sorbent materials and a thermal desorption-gas chromatography-mass spectrometry method (TD-GC-MS). Experiments were conducted to identify suitable sorbent materials and tubes for analysis. Breakthrough, desorption rate, the effects of storage and desorption temperatures were investigated and different drying methods were established with respect to quantitative sampling and formation of DMDS. Proton-transfer-reaction mass spectrometry (PTR-MS) was used in the development of the method and was an especially useful tool for determination of breakthrough. The results show that glass tubes packed with silica gel for pre-concentration of MT before analysis with TD-GC-MS give the best results. In addition, a combination of Tenax TA and carbonised molecular sieve or Tenax TA cooled to 0 °C gives acceptable results. 80 °C was found to be the optimal desorption temperature. For all the sampling methods tested, storage conditions were observed to be very critical for transformation of MT. Room temperature storage should be limited to few minutes and, in general, tubes should be kept at 0°C or lower during storage.
[King2012] King, J., K. Unterkofler, G. Teschl, S. Teschl, P. Mochalski, H. Koc, H. Hinterhuber, and A. Amann, "A modeling-based evaluation of isothermal rebreathing for breath gas analyses of highly soluble volatile organic compounds", Journal of breath research, vol. 6, no. 1: IOP Publishing, pp. 016005, 2012.
Link: http://iopscience.iop.org/1752-7163/6/1/016005
Abstract
Isothermal rebreathing has been proposed as an experimental technique for estimating the alveolar levels of hydrophilic volatile organic compounds (VOCs) in exhaled breath. Using the prototypic test compounds acetone and methanol, we demonstrate that the end-tidal breath profiles of such substances during isothermal rebreathing show a characteristic increase that contradicts the conventional pulmonary inert gas elimination theory due to Farhi. On the other hand, these profiles can reliably be captured by virtue of a previously developed mathematical model for the general exhalation kinetics of highly soluble, blood-borne VOCs, which explicitly takes into account airway gas exchange as a major determinant of the observable breath output. This model allows for a mechanistic analysis of various rebreathing protocols suggested in the literature. In particular, it predicts that the end-exhaled levels of acetone and methanol measured during free tidal breathing will underestimate the underlying alveolar concentration by a factor of up to 1.5. Moreover, it clarifies the discrepancies between in vitro and in vivo blood–breath ratios of hydrophilic VOCs and yields further quantitative insights into the physiological components of isothermal rebreathing and highly soluble gas exchange in general.
[Jordan2012] Jordan, A., C. Lindinger, L. Märk, P. Sulzer, S. Juerschik, H. Seehauser, and TD. Märk, "Monitoring and Quantifying Toxic Industrial Compounds (TICs) with Proton with Proton-Transfer-Reaction Mass Spectrometry (PTR Reaction Mass Spectrometry (PTR-MS)", : IONICON Analytik, 2012.
Link: http://www.ionicon.com/sites/default/files/uploads/doc/poster_ionicon_pittcon_2012_tics.pdf
[Papurello2012] Papurello, D., C. Soukoulis, E. Schuhfried, L. Cappellin, F. Gasperi, S. Silvestri, M. Santarelli, and F. Biasioli, "Monitoring of volatile compound emissions during dry anaerobic digestion of the Organic Fraction of Municipal Solid Waste by Proton Transfer Reaction Time-of-Flight Mass Spectrometry.", Bioresour Technol, vol. 126: Fondazione Edmund Mach, Biomass and Renewable Energy Unit, Via E. Mach 1, 38010 San Michele a/A, Italy., pp. 254–265, Dec, 2012.
Link: http://dx.doi.org/10.1016/j.biortech.2012.09.033
Abstract
Volatile Organic Compounds (VOCs) formed during anaerobic digestion of aerobically pre-treated Organic Fraction of Municipal Solid Waste (OFMSW), have been monitored over a 30 day period by a direct injection mass spectrometric technique: Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). Most of the tentatively identified compounds exhibited a double-peaked emission pattern which is probably the combined result from the volatilization or oxidation of the biomass-inherited organic compounds and the microbial degradation of organic substrates. Of the sulfur compounds, hydrogen sulfide had the highest accumulative production. Alkylthiols were the predominant sulfur organic compounds, reaching their maximum levels during the last stage of the process. H(2)S formation seems to be influenced by the metabolic reactions that the sulfur organic compounds undergo, such as a methanogenesis induced mechanism i.e. an amino acid degradation/sulfate reduction. Comparison of different batches indicates that PTR-ToF-MS is a suitable tool providing information for rapid in situ bioprocess monitoring.

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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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