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Scientific Articles - PTR-MS Bibliography

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Found 677 results
Title [ Year(Asc)]
2015
[1582] Beale, R., J. L. Dixon, T. J. Smyth, and P. D. Nightingale, "Annual study of oxygenated volatile organic compounds in UK shelf waters", Marine Chemistry, vol. 171, pp. 96¬106, Apr, 2015.
Link: http://dx.doi.org/10.1016/j.marchem.2015.02.013
Abstract
We performed an annual study of oxygenated volatile organic compound (OVOC) seawater concentrations at a site off Plymouth, UK in the Western English Channel over the period of February 2011–March 2012. Acetone concentrations ranged from 2–10 nM (nanomole/L) in surface waters with a maximum observed in summer. Concentrations correlated positively with net shortwave radiation and UV light, suggestive of photochemically linked acetone production. We observed a clear decline in acetone concentrations below the mixed layer. Acetaldehyde varied between 4–37 nM in surface waters with higher values observed in autumn and winter. Surface concentrations of methanol ranged from 16–78 nM, but no clear annual cycle was observed. Methanol concentrations exhibited considerable inter-annual variability. We estimate consistent deposition to the sea surface for acetone and methanol but that the direction of the acetaldehyde flux varies during the year
[1612] Feilberg, A., P. Bildsoe, and T. Nyord, "Application of PTR-MS for measuring odorant emissions from soil application of manure slurry.", Sensors (Basel), vol. 15, pp. 1148–1167, 2015.
Link: http://dx.doi.org/10.3390/s150101148
Abstract
<p>Odorous volatile organic compounds (VOC) and hydrogen sulfide (H2S) are emitted together with ammonia (NH3) from manure slurry applied as a fertilizer, but little is known about the composition and temporal variation of the emissions. In this work, a laboratory method based on dynamic flux chambers packed with soil has been used to measure emissions from untreated pig slurry and slurry treated by solid-liquid separation and ozonation. Proton-transfer-reaction mass spectrometry (PTR-MS) was used to provide time resolved data for a range of VOC, NH3 and H2S. VOC included organic sulfur compounds, carboxylic acids, phenols, indoles, alcohols, ketones and aldehydes. H2S emission was remarkably observed to take place only in the initial minutes after slurry application, which is explained by its high partitioning into the air phase. Long-term odor effects are therefore assessed to be mainly due to other volatile compounds with low odor threshold values, such as 4-methylphenol. PTR-MS signal assignment was verified by comparison to a photo-acoustic analyzer (NH3) and to thermal desorption GC/MS (VOC). Due to initial rapid changes in odorant emissions and low concentrations of odorants, PTR-MS is assessed to be a very useful method for assessing odor following field application of slurry. The effects of treatments on odorant emissions are discussed.</p>
[1576] Lanza, M., J. W. Acton, P. Sulzer, K. Breiev, S. Juerschik, A. Jordan, E. Hartungen, G. Hanel, L. Maerk, T. D. Maerk, et al., "Selective reagent ionisation-time of flight-mass spectrometry: a rapid technology for the novel analysis of blends of new psychoactive substances", Journal of Mass Spectrometry, vol. 50, pp. 427–431, 2015.
Link: http://dx.doi.org/10.1002/jms.3514
Abstract
In this study we demonstrate the potential of selective reagent ionisation-time of flight-mass spectrometry for the rapid and selective identification of a popular new psychoactive substance blend called ‘synthacaine’, a mixture that is supposed to imitate the sensory and intoxicating effects of cocaine. Reactions with H3O+ result in protonated parent molecules which can be tentatively assigned to benzocaine and methiopropamine. However, by comparing the product ion branching ratios obtained at two reduced electric field values (90 and 170 Td) for two reagent ions (H3O+ and NO+) to those of the pure chemicals, we show that identification is possible with a much higher level of confidence then when relying solely on the m/z of protonated parent molecules. A rapid and highly selective analytical identification of the constituents of a recreational drug is particularly crucial to medical personnel for the prompt medical treatment of overdoses, toxic effects or allergic reactions. Copyright © 2015 John Wiley & Sons, Ltd.
2014
[1478] Schmidberger, T., R. Gutmann, K. Bayer, J. Kronthaler, and R. Huber, "Advanced online monitoring of cell culture off-gas using proton transfer reaction mass spectrometry", Biotechnology Progress, pp. n/a–n/a, 2014.
Link: http://dx.doi.org/10.1002/btpr.1853
Abstract
<p>Mass spectrometry has been frequently applied to monitor the O2 and CO2 content in the off-gas of animal cell culture fermentations. In contrast to classical mass spectrometry the proton transfer reaction mass spectrometry (PTR-MS) provides additional information of volatile organic compounds by application of a soft ionization technology. Hence, the spectra show less fragments and can more accurately assigned to particular compounds. In order to discriminate between compounds of non-metabolic and metabolic origin cell free experiments and fed-batch cultivations with a recombinant CHO cell line were conducted. As a result, in total eight volatiles showing high relevance to individual cultivation or cultivation conditions could be identified. Among the detected compounds methanethiol, with a mass-to-charge ratio of 49, qualifies as a key candidate in process monitoring due to its strong connectivity to lactate formation. Moreover, the versatile and complex data sets acquired by PTR MS provide a valuable resource for statistical modeling to predict non direct measurable parameters. Hence, partial least square regression was applied to the complete spectra of volatiles measured and important cell culture parameters such as viable cell density estimated (R2&thinsp;=&thinsp;0.86). As a whole, the results of this study clearly show that PTR-MS provides a powerful tool to improve bioprocess-monitoring for mammalian cell culture. Thus, specific volatiles emitted by cells and measured online by the PTR-MS and complex variables gained through statistical modeling will contribute to a deeper process understanding in the future and open promising perspectives to bioprocess control. &copy; 2014 American Institute of Chemical Engineers Biotechnol. Prog., 2014</p>
[1516] Misztal, P.. K., T.. Karl, R.. Weber, H.. H. Jonsson, A.. B. Guenther, and A.. H. Goldstein, "Airborne flux measurements of biogenic volatile organic compounds over California", Atmospheric Chemistry and Physics Discussions, vol. 14, pp. 7965–8013, Mar, 2014.
Link: http://www.atmos-chem-phys-discuss.net/14/7965/2014/acpd-14-7965-2014.html
Abstract
<p>Biogenic Volatile Organic Compound (BVOC) fluxes were measured onboard the CIRPAS Twin Otter aircraft as part of the California Airborne BVOC Emission Research in Natural Ecosystem Transects (CABERNET) campaign during June 2011. The airborne virtual disjunct eddy covariance (AvDEC) approach used measurements from a PTR-MS and a wind radome probe to directly determine fluxes of isoprene, MVK + MAC, methanol, monoterpenes, and MBO over 10 000 km of flight paths focusing on areas of California predicted to have the largest emissions of isoprene. The Fast Fourier Transform (FFT) approach was used to calculate fluxes over long transects of more than 15 km, most commonly between 50 and 150 km. The Continuous Wavelet Transformation (CWT) approach was used over the same transects to also calculate &quot;instantaneous&quot; fluxes with localization of both frequency and time independent of non-stationarities. Vertical flux divergence of isoprene is expected due to its relatively short lifetime and was measured directly using &quot;racetrack&quot; profiles at multiple altitudes. It was found to be linear and in the range 5% to 30% depending on the ratio of aircraft altitude to PBL height (z / zi). Fluxes were generally measured by flying consistently at 400 &plusmn; 50 m (a.g.l.) altitude, and extrapolated to the surface according to the determined flux divergence. The wavelet-derived surface fluxes of isoprene averaged to 2 km spatial resolution showed good correspondence to Basal Emission Factor (BEF) landcover datasets used to drive biogenic VOC (BVOC) emission models. The surface flux of isoprene was close to zero over Central Valley crops and desert shrublands, but was very high (up to 15 mg m&minus;2 h&minus;1) above oak woodlands, with clear dependence of emissions on temperature and oak density. Isoprene concentrations of up to 8 ppb were observed at aircraft height on the hottest days and over the dominant source regions. While isoprene emissions from agricultural crop regions, shrublands, and coniferous forests were extremely low, high concentrations of methanol and monoterpenes were found above some of these regions. These observations demonstrate the ability to measure fluxes from specific sources by eddy covariance from an aircraft, and suggest the utility of measurements using fast response chemical sensors to constrain emission inventories and map out source distributions for a much broader array of trace gases than was observed in this study. This paper reports the first regional direct eddy covariance fluxes of isoprene. The emissions of VOCs measured from aircraft with 2 km spatial resolution can quantify the distribution of major sources providing the observations required for testing statewide emission inventories of these important trace gases. These measurements will be used in a future study to assess BVOC emission models and their driving variable datasets.</p>
[1560] Jankowski, M. Jan, R. Olsen, C. Nielsen, Y. Thomassen, and P. Molander, "The applicability of proton transfer reaction-mass spectrometry (PTR-{MS}) for determination of isocyanic acid ({ICA}) in work room atmospheres", Environmental Science: Processes & Impacts, 2014.
Link: http://dx.doi.org/10.1039/C4EM00363B
Abstract
<p>A method is presented for the real-time quantitative determination of isocyanic acid (ICA) in air using proton transfer reaction-mass spectrometry (PTR-MS). Quantum mechanical calculations were performed to establish the ion-polar molecule reaction rate of ICA and other isocyanates. The PTR-MS was calibrated against different ICA air concentrations and humidity conditions using Fourier transform-infrared spectroscopy (FT-IR) as quantitative reference. Based on these experiments a simple humidity dependant model was derived for correction of the PTR-MS response for ICA. The corrected PTR-MS data was linearly correlated (R2 &gt; 0.99) with the data acquired by FT-IR. The PTR-MS instrumental limit of detection (LOD) for ICA was 2.3 ppb. Humid atmospheres resulted in LODs of 3.4 and 7.8 ppb, at an absolute humidity (AH) of 4.0 and 15.5 g m-3, respectively. Furthermore, off-line sampling using denuder and impinger samplers using di-n-butylamine (DBA) as derivatization reagent was compared with PTR-MS measurements in a dynamically generated standard ICA atmosphere. Denuder (n = 4) and impinger (n = 4) sampling subsequent to liquid chromatography mass spectrometry (LC-MS) determination compared to corrected PTR-MS data resulted in recoveries of 79.6 (8.1 % RSD) and 99.9 (9.3 % RSD) %, respectively. Measurements of ICA from thermally decomposed cured 1,6-hexamethylene diisocyanate (HDI)-paint was performed used PTR-MS and denuder (n = 3) sampling. The relation between the average ICA responses using denuders (34.4 ppb) and PTR-MS (42.6 ppb) was 80.6 %, which coincided well with the relative recovery obtained from the controlled laboratory experiments using dynamically generated ICA atmospheres (79.6 %). The variability in ICA air concentration during the welding process (170 % RSDPTR-MS) illustrated the need for real-time measurements.</p>
[1532] Schripp, T.., S.. Etienne, C.. Fauck, F.. Fuhrmann, L.. Märk, and T.. Salthammer, "Application of proton-transfer-reaction-mass-spectrometry for Indoor Air Quality research", Indoor Air, vol. 24, pp. 178–189, 2014.
Link: http://dx.doi.org/10.1111/ina.12061
Abstract
<p>In the field of Indoor Air Quality research, the measurement of volatile organic compounds (VOCs) demands instruments that are rapid, mobile, robust, highly sensitive and allow for simultaneous monitoring of multiple compounds. These instruments should also compensate for possible interferences from permanent gases and air humidity. Proton-transfer-reaction-mass-spectrometry (PTR-MS) has proved to be a valuable and promising technique that fits the mentioned requirements for a suitable online measuring device. In this study, five exemplary applications of PTR-MS are described: (i) release of paint additives during drying process, (ii) emission of VOCs from active hardcopy devices, (iii) reference material evaluation, (iv) diffusion studies, and (v) emission testing of building products. The examples are selected to illustrate possibilities and limitations of the PTR technique in this field of research. The quadruple-based PTR-QMS was able to determine the emission characteristics during the experiments, especially in case of depleting emission sources (e.g., reference material). This allows for chemometrical analysis of the measured release patterns and detection of underlying processes. However, PTR-QMS reaches a functional limit in case of compound identification. If identification of VOCs is necessary, the measurements need to be accompanied by GC/MS analytics or a PTR instrument with higher mass-resolution (e.g., PTR-TOF-MS).</p>
[1548] Aprea, E., L. Cappellin, F. Gasperi, F. Morisco, V. Lembo, A. Rispo, R. Tortora, P. Vitaglione, N. Caporaso, and F. Biasioli, "Application of PTR-TOF-{MS} to investigate metabolites in exhaled breath of patients affected by coeliac disease under gluten free diet", Journal of Chromatography B, vol. 966, pp. 208–213, Sep, 2014.
Link: http://dx.doi.org/10.1016/j.jchromb.2014.02.015
Abstract
<p>Coeliac disease (CD) is a common chronic inflammatory disorder of the small bowel induced in genetically susceptible people by the exposure to gliadin gluten. Even though several tests are available to assist the diagnosis, CD remains a biopsy-defined disorder, thus any non-invasive or less invasive diagnostic tool may be beneficial. The analysis of volatile metabolites in exhaled breath, given its non-invasive nature, is particularly promising as a screening tool of disease in symptomatic or non-symptomatic patients. In this preliminary study the proton transfer reaction time of flight mass spectrometry coupled to a buffered end-tidal on-line sampler to investigate metabolites in the exhaled breath of patients affected by coeliac disease under a gluten free diet was applied. Both H3O+ or NO+ were used as precursor ions. In our investigation no differences were found in the exhaled breath of CD patients compared to healthy controls. In this study, 33 subjects were enrolled: 16 patients with CD, all adhering a gluten free diet, and 17 healthy controls. CD patients did not show any symptom of the disease at the time of breath analysis; thus the absence of discrimination from healthy controls was not surprising.</p>
[1610] Tres, A., S. P. Heenan, and S. { van Ruth}, "Authentication of dried distilled grain with solubles (DDGS) by fatty acid and volatile profiling.", Lebenson Wiss Technol, vol. 59, pp. 215–221, Nov, 2014.
Link: http://dx.doi.org/10.1016/j.lwt.2014.05.044
Abstract
<p>Demand for ethanol substituted fuels from the utilisation of cereal based biofuel has resulted in an over production of dried distillers grains with solubles (DDGS) that are now readily available on the animal feed market. With this rapid emerging availability comes potential variability in the nutritional value of DDGS and possible risks of feed contaminants. Subsequently, the authentication and traceability of alternative animal feed sources is of high priority. In this study and as part of the EU research project &quot;Quality and Safety of Feeds and Food for Europe (QSAFFE FP7-KBBE-2010-4) an attempt was made to classify the geographical origin of cereal grains used in the production of DDGS material. DDGS material of wheat and corn origin were obtained from Europe, China, and the USA. Fatty acid profiles and volatile fingerprints were assessed by gas chromatography flame ionisation (GC-FID) and rapid proton transfer reaction mass spectrometry (PTR-MS) respectively. Chemometric analysis of fatty acid profiles and volatile fingerprints allowed for promising classifications of cereals used in DDGS material by geographical and botanical origin and enabled visual representation of the data. This objective analytical approach could be adapted for routine verification of cereal grains used in the production of DDGS material.</p>
[1608] Papurello, D., A. Lanzini, P. Leone, M. Santarelli, and S. Silvestri, "Biogas from the organic fraction of municipal solid waste: dealing with contaminants for a solid oxide fuel cell energy generator.", Waste Manag, vol. 34, pp. 2047–2056, Nov, 2014.
Link: http://dx.doi.org/10.1016/j.wasman.2014.06.017
Abstract
<p>The present work investigates electricity production using a high efficiency electrochemical generator that employs as fuel a biogas from the dry anaerobic digestion of the organic fraction of municipal solid waste (OFMSW). The as-produced biogas contains several contaminants (sulfur, halogen, organic silicon and aromatic compounds) that can be harmful for the fuel cell: these were monitored via an innovative mass spectrometry technique that enables for in-line and real-time quantification. A cleaning trap with activated carbons for the removal of sulfur and other VOCs contained in the biogas was also tested and monitored by observing the different breakthrough times of studied contaminants. The electrochemical generator was a commercial Ni anode-supported planar Solid Oxide Fuel Cell (SOFC), tested for more than 300 h with a simulated biogas mixture (CH4 60 vol.%, CO2 40 vol.%), directly fed to the anode electrode. Air was added to promote the direct internal conversion of CH4 to H2 and CO via partial oxidation (POx). The initial breakthrough of H2S from the cleaning section was also simulated and tested by adding &sim;1 ppm(v) of sulfur in the anode feed; a full recovery of the fuel cell performance after 24h of sulfur exposure (&sim;1 ppm(v)) was observed upon its removal, indicating the reliable time of anode exposure to sulfur in case of exhausted guard bed.</p>
[1515] Park, J.-H.., S.. Fares, R.. Weber, and A.. H. Goldstein, "Biogenic volatile organic compound emissions during BEARPEX 2009 measured by eddy covariance and flux-gradient similarity methods", Atmospheric Chemistry and Physics, vol. 14, pp. 231–244, Jan, 2014.
Link: http://nature.berkeley.edu/ahg/pubs/Park et al-acp-14-231-2014.pdf
Abstract
<p>The Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) took place in Blodgett Forest, a Ponderosa pine forest in the Sierra Nevada of California, USA, during summer 2009. We deployed a proton transfer reaction&ndash;quadrupole mass spectrometer (PTR-QMS) to measure fluxes and concentrations of biogenic volatile organic compounds (BVOCs). Eighteen ion species, including the major BVOC expected at the site, were measured sequentially at 5 heights to observe their vertical gradient from the forest floor to above the canopy. Fluxes of the 3 dominant BVOCs methanol, 2-Methyl-3-butene-2-ol (MBO), and monoterpenes were measured above the canopy by the disjunct eddy covariance (EC) method. Canopy-scale fluxes were also determined by the flux&ndash;gradient similarity method (K-theory). A universal K (Kuniv) was determined as the mean of individual K&#39;s calculated from the measured fluxes divided by vertical gradients for methanol, MBO, and monoterpenes. This Kuniv was then multiplied by the gradients of each observed ion species to compute their fluxes. The flux&ndash;gradient similarity method showed very good agreement with the disjunct EC method. Fluxes are presented for all measured species and compared to historical measurements from the same site, and used to test emission algorithms used to model fluxes at the regional scale. MBO was the dominant emission observed, followed by methanol, monoterpenes, acetone, and acetaldehyde. The flux&ndash;gradient similarity method is shown to be tenable, and we recommend its use, especially in experimental conditions when fast measurement of BVOC species is not available.</p>
[1566] Stockwell, C.. E., P.. R. Veres, J.. Williams, and R.. J. Yokelson, "Characterization of biomass burning smoke from cooking fires, peat, crop residue and other fuels with high resolution proton-transfer-reaction time-of-flight mass spectrometry", Atmospheric Chemistry and Physics Discussions, vol. 14, pp. 22163–22216, 2014.
Link: http://dx.doi.org/10.5194/acpd-14-22163-2014
Abstract
<p>We deployed a high-resolution proton-transfer-reaction time-of-flight mass spectrom-eter (PTR-TOF-MS) to measure biomass burning emissions from peat, crop-residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experi-ment (FLAME-4) laboratory campaign. A combination of gas standards calibrations and 5 composition sensitive, mass dependent calibration curves were applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign best identities to most major &quot;exact masses&quot; including many high molecular mass species. Using these methods ap-proximately 80&ndash;96 % of the total NMOC mass detected by PTR-TOF-MS and FTIR was 10 positively or tentatively identified for major fuel types. We report data for many rarely measured or previously unmeasured emissions in several compound classes including aromatic hydrocarbons, phenolic compounds, and furans; many of which are suspected secondary organic aerosol precursors. A large set of new emission factors (EFs) for a range of globally significant biomass fuels is presented. Measurements show that 15 oxygenated NMOCs accounted for the largest fraction of emissions of all compound classes. In a brief study of various traditional and advanced cooking methods, the EFs for these emissions groups were greatest for open 3-stone cooking in comparison to their more advanced counterparts. Several little-studied nitrogen-containing organic compounds were detected from many fuel types that together accounted for 0.1&ndash;8.7 % 20 of the fuel nitrogen and some may play a role in new particle formation.</p>
[1465] Sinha, V., V. Kumar, and C. Sarkar, "Chemical composition of pre-monsoon air in the Indo-Gangetic Plain measured using a new PTR-MS and air quality facility: high surface ozone and strong influence of biomass burning", Atmos. Chem. Phys., vol. 14, pp. 5921-5941, 2014.
Link: http://www.atmos-chem-phys.net/14/5921/2014/acp-14-5921-2014.html
Abstract
<p>One seventh of the world population lives in the Indo&ndash;Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia. Yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides is not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India&#39;s first high sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and meteorological station, was used to quantify in-situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (N. W. IGP). Westerly winds arriving at high wind speeds (5&ndash;20 m s&minus;1) in the pre-monsoon season at the site, were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May 2012 ranged from 1.2&ndash;1.7 nmol mol&minus;1 for aromatic VOCs, 5.9&ndash;37.4 nmol mol&minus;1 for the oxygenated VOCs, 1.4 nmol mol&minus;1 for acetonitrile, 1.9 nmol mol&minus;1 for isoprene, 567 nmol mol&minus;1 for carbon monoxide, 57.8 nmol mol&minus;1 for ozone, 11.5 nmol mol&minus;1 for nitrogen oxides, 7.3 nmol mol&minus;1 for sulphur dioxide, 104 μg m&minus;3 for PM2.5 and 276 μg m&minus;3 for PM10. By analyzing the one minute in-situ data with meteorological parameters and applying chemical tracers (e.g. acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning activity caused massive increases (&gt; 3 times of baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant source for oxygenated VOCs and isoprene (r2 with acetonitrile &ge; 0.5 for night-time data), which is remarkable in terms of atmospheric chemistry implications. Surface ozone exceeded the 8 h national ambient air quality limit of 100 μg O3 m&minus;3 on a daily basis, except for 17 May 2012, when a severe dust storm event (PM2.5 &gt; 800 μg m&minus;3; PM10 &gt; 2700 μg m&minus;3) characterized by long range transport from the west impacted the site. The novel dataset and results point to occurrence of high primary emissions of reactive VOCs. They also highlight the urgent need for establishing more comprehensive observational facilities in the IGP to constrain the spatial and seasonal variability of atmospheric chemical constituents. Such efforts will enable mechanistic level understanding of the in-situ chemical processes controlling formation of surface ozone, a necessary step for effective ozone mitigation and improvement of the regional air quality.</p>
[1605] Taiti, C., C. Costa, P. Menesatti, D. Comparini, N. Bazihizina, E. Azzarello, E. Masi, and S. Mancuso, "Class-modeling approach to PTR-TOFMS data: a peppers case study.", J Sci Food Agric, May, 2014.
Link: http://dx.doi.org/10.1002/jsfa.6761
Abstract
<p>Proton transfer reaction-mass spectrometry (PTR-MS), in its recently developed implementation based on time-of-flight mass spectrometry (PTR-TOFMS), was used to rapidly determine the volatile compounds present in fruits of Capsicum spp.We analyzed the volatile organic compounds emission profile of freshly cut chili peppers belonging to three species and 33 different cultivars. PTR-TOFMS data, analyzed with appropriate and advanced multivariate class-modeling approaches, perfectly discriminated among the three species (100% correct classification in validation set). VIP (variable importance in projection) scores were used to select the 15 most important volatile compounds in discriminating the species. The best candidates for Capsicum spp. were compounds with measured m/z of 63.027, 101.096 and 107.050, which were, respectively, tentatively identified as dimethyl sulfide, hexanal and benzaldehyde.Based on the promising results, the possibility of introducing multivariate class-modeling techniques, different from the classification approaches, in the field of volatile compounds analyses is discussed. &copy; 2014 Society of Chemical Industry.</p>
[1544] Mueller, M.., T.. Mikoviny, S.. Feil, S.. Haidacher, G.. Hanel, E.. Hartungen, A.. Jordan, L.. Maerk, P.. Mutschlechner, R.. Schottkowsky, et al., "A compact PTR-ToF-MS instrument for airborne measurements of VOCs at high spatio-temporal resolution", Atmospheric Measurement Techniques Discussions, vol. 7, pp. 5533–5558, 2014.
Link: http://www.atmos-meas-tech-discuss.net/7/5533/2014/
Abstract
<p><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">Herein, we report on the development of a compact proton-transfer-reaction time-of-flight mass spectrometer for airborne measurements of volatile organic compounds (VOCs). The new instrument resolves isobaric ions with a mass resolving power (</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">/Δ</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">) of ~ 1000, provides accurate&nbsp;</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m/z</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">&nbsp;measurements (Δ</span><i style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">m</i><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica; font-size: 12px; line-height: 20px; background-color: rgb(255, 255, 255);">&nbsp;&lt; 3 mDa), records full mass spectra at 1 Hz and thus overcomes some of the major analytical deficiencies of quadrupole-MS based airborne instruments. 1 Hz detection limits for biogenic VOCs (isoprene, α-pinene), aromatic VOCs (benzene, toluene, xylenes) and ketones (acetone, methyl ethyl ketone) range from 0.05 to 0.12 ppbV, making the instrument well-suited for fast measurements in the continental boundary layer. The instrument detects and quantifies VOCs in locally confined plumes (&lt; 1km) which improves our capability of characterizing emission sources and atmospheric processing within plumes. A deployment during the NASA 2013 DISCOVER-AQ mission generated high vertical and horizontal resolution in situ data of VOCs and ammonia for validation of satellite retrievals and chemistry transport models.</span></p>
[1549] Karl, T., L. Kaser, and A. Turnipseed, "Eddy covariance measurements of isoprene and 232-MBO based on NO+ time-of-flight mass spectrometry", International Journal of Mass Spectrometry, vol. 365-366, pp. 15 - 19, 2014.
Link: http://www.sciencedirect.com/science/article/pii/S1387380613004272
Abstract
<p>Abstract Isoprene and 2-methyl-3-buten-2-ol (232-MBO) are the dominant biogenic \{VOCs\} released throughout the US, thus requiring simultaneous measurements. Recent measurements suggest the presence of isoprene in 232-MBO dominated ecosystems, however analytical difficulties make it problematic to detect both species independently. Based on a new chemical ionization scheme we use eddy covariance measurements to selectively measure fluxes of both species without analytical interference at the Manitou Experimental Forest (MEF) in Colorado. Our measurements show a concentration ratio between isoprene and 232 \{MBO\} of 0.24 (ppbv/ppbv), and a flux ratio of 0.10 ([ppbv&nbsp;m/s]/[ppbv&nbsp;m/s]). Daytime average emission factors of isoprene and 232 \{MBO\} were 1.4&nbsp;Â&plusmn;&nbsp;0.3 and 16.0&nbsp;Â&plusmn;&nbsp;3.0&nbsp;mg/m2/h respectively. Both compounds exhibit light and temperature dependent fluxes. These findings suggest that isoprene is both locally produced and transported to the measurement site dominated by ponderosa pine. This makes it difficult to use \{MVK\} and \{MAC\} as tracers for estimating the photochemical age of isoprene chemistry at this site. Further our measurements suggest that isoprene can contribute to about 15% of the \{OH\} reactivity relative to 232 MBO.</p>
[1528] Zardini, A. A., S. M. Platt, M. Clairotte, I. El Haddad, B. Temime, N. Marchand, I. Jezek, L. Drinovec, G. Mocnik, J. G. Slowik, et al., "Effects of alkylate fuel on exhaust emissions and secondary aerosol formation of a 2- stroke and a 4-stroke scooter", Atmospheric Environment, Mar, 2014.
Link: http://dx.doi.org/10.1016/j.atmosenv.2014.03.024
Abstract
<p>Regulated and unregulated emissions from a 2-stroke and a 4-stroke scooter were characterized during a legislative driving cycle in a certified laboratory. Scooter exhaust was analyzed at the tailpipe, in a dilution tunnel, and partly collected in a mobile smog chamber for photochemical ageing. We present evidence that the photochemically aged exhaust from a 2-stroke and a 4-stroke scooter produces considerable amounts of secondary organic aerosol: from 1.5 to 22.0 mg/km, and from 5.5 to 6.6 mg/km, respectively. Tests were repeated after replacing the standard petrol and synthetic lube oil with an alkylate fuel (with low content of aromatic compounds) and ultra-clean lube oil (low ash forming potential). We observed emission reduction (with some exceptions) for several gaseous and particulate phase species, in particular for carbon monoxide (from 8% up to 38% and from 31% to 50%, for the 2-stroke and the 4-stroke scooters, respectively), particulate mass (from 32% up to 75% for the 2-stroke scooter), aromatic compounds (89% and 97% for the 2-stroke and the 4-stroke scooter, respectively), and secondary organic aerosol (from 87% to 100% and 99% for the 2-stroke and the 4-stroke scooters, respectively). We attribute the organic aerosol reduction to the absence of aromatics in the alkylate fuel.</p>
[1601] Liu, D., M. Marie Løkke, A. Leegaard Riis, K. Mortensen, and A. Feilberg, "Evaluation of clay aggregate biotrickling filters for treatment of gaseous emissions from intensive pig production.", J Environ Manage, vol. 136, pp. 1–8, Apr, 2014.
Link: http://dx.doi.org/10.1016/j.jenvman.2014.01.023
Abstract
<p>Treatment of ventilation air from livestock production by biological airfiltration has emerged as a cost-effective technology for reduction of emissions of odorants and ammonia. Volatile sulfur compounds from livestock production include H2S and methanethiol, which have been identified as potentially important odorants that are not removed sufficiently by biological air filters. Light-expanded clay aggregates (Leca(&reg;)) is a biotrickling filter material that contains iron oxides, which can oxidize H2S and methanethiol, and thus potentially may help to remove these two compounds in biological air filters. This study used on-line PTR-MS measurements to investigate the performances of two Leca(&reg;) biotrickling filters (abraded Leca(&reg;) filter and untreated Leca(&reg;) filter) for removal of odorants and ammonia emitted from an experimental pig house. The results indicated that the abraded Leca(&reg;) filter had a similar or slightly better capability for removing odorants than the untreated Leca(&reg;) filter. This may be due to the enlargement of the surface area by the friction process. The volatile sulfur compounds, however, were not removed efficiently by either of the two Leca(&reg;) filters. Kinetic analysis of a ventilation controlled experiment during the first period indicated that Grau second-order kinetics could be applied to analyze the removal of sulfur compounds and other odorants, whereas the Stover-Kincannon model could only be applied to analyze the removal of odorants other than sulfur compounds, partly due to the limitation of mass transfer of these compounds in the biotrickling filters. In the last measurement period, a production of dimethyl disulfide and dimethyltrisulfide coinciding with strongly enhanced removal of methanethiol was observed for the untreated filter. This was assumed to be enhanced by an incidence of low local air velocity in the filter and indicated involvement of iron-catalyzed reactions in the removal of sulfur compounds.</p>
[1526] Gloess, A. N., A. Vietri, F. Wieland, S. Smrke, B. Schönbächler, J. A. Sanchez Lopez, S. Petrozzi, S. Bongers, T. Koziorowski, and C. Yeretzian, "Evidence of different flavour formation dynamics by roasting coffee from different origins: On-line analysis with PTR-ToF-{MS}", International Journal of Mass Spectrometry, Feb, 2014.
Link: http://www.sciencedirect.com/science/article/pii/S1387380614000657
Abstract
<p>Coffees from different origins were roasted to different roast degrees and along varying time temperature roasting profiles. The formation of volatile organic compounds (VOCs) during roasting was analyzed on-line by proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS). Coffee samples were Coffea arabica from Colombia, Guatemala (Antigua La Ceiba), Ethiopia (Yirga Cheffe, Djimmah) and Coffea canephora var. robusta from Indonesia (Malangsari). The roasting profiles ranged from high temperature short time (HTST) to low temperature long time (LTLT) roasting, and from medium to dark roast degree. The release dynamics of the on-line monitored VOCs differed for the different coffees and showed a strong modulation with the time&ndash;temperature roasting profile. While for Guatemalan coffee the formation of VOCs started relatively early in the roasting process, the VOC formation started much later in the case of Yirga Cheffe and Malangsari. Off-line analysis of the coffee brew augmented the measurements. These included headspace solid phase micro extraction gas chromatography mass spectrometry (HS SPME GC/MS), content of total solids, chlorogenic acids, caffeine, total polyphenols (Folin Ciocalteu), organic acids (ion chromatography), titratable acidity and pH. Some general trends, irrespective of the coffee origin, were observed, such as an increase in pH when going from an HTST to an LTLT profile or from a medium to dark roast degree. Furthermore, a decrease of total headspace intensity was observed from an HTST to an LTLT roasting profile. In general, the changes of the time temperature roasting profiles and/or the roast degree influenced the intensity of the respective coffee constituents as well as their relative composition differently for different coffee origins.</p>
[1607] Borduas, N., G. { da Silva}, J. G. Murphy, and J. P. D. Abbatt, "Experimental and Theoretical Understanding of the Gas Phase Oxidation of Atmospheric Amides with OH Radicals: Kinetics, Products, and Mechanisms.", J Phys Chem A, Jul, 2014.
Link: http://dx.doi.org/10.1021/jp503759f
Abstract
<p>Atmospheric amides have primary and secondary sources and are present in ambient air at low pptv levels. To better assess the fate of amides in the atmosphere, the room temperature (298 &plusmn; 3 K) rate coefficients of five different amides with OH radicals were determined in a 1 m(3) smog chamber using online proton-transfer-reaction mass spectrometry (PTR-MS). Formamide, the simplest amide, has a rate coefficient of (4.44 &plusmn; 0.46) &times; 10(-12) cm(3) molec(-1) s(-1) against OH, translating to an atmospheric lifetime of &sim;1 day. N-methylformamide, N-methylacetamide and propanamide, alkyl versions of formamide, have rate coefficients of (10.1 &plusmn; 0.6) &times; 10(-12), (5.42 &plusmn; 0.19) &times; 10(-12), and (1.78 &plusmn; 0.43) &times; 10(-12) cm(3) molec(-1) s(-1), respectively. Acetamide was also investigated, but due to its slow oxidation kinetics, we report a range of (0.4-1.1) &times; 10(-12) cm(3) molec(-1) s(-1) for its rate coefficient with OH radicals. Oxidation products were monitored and quantified and their time traces were fitted using a simple kinetic box model. To further probe the mechanism, ab initio calculations are used to identify the initial radical products of the amide reactions with OH. Our results indicate that N-H abstractions are negligible in all cases, in contrast to what is predicted by structure-activity relationships. Instead, the reactions proceed via C-H abstraction from alkyl groups and from formyl C(O)-H bonds when available. The latter process leads to radicals that can readily react with O2 to form isocyanates, explaining the detection of toxic compounds such as isocyanic acid (HNCO) and methyl isocyanate (CH3NCO). These contaminants of significant interest are primary oxidation products in the photochemical oxidation of formamide and N-methylformamide, respectively.</p>
[1611] Granato, D., A. Koot, and S. M. { van Ruth}, "Geographical provenancing of purple grape juices from different farming systems by proton transfer reaction mass spectrometry using supervised statistical techniques.", J Sci Food Agric, Nov, 2014.
Link: http://dx.doi.org/10.1002/jsfa.7001
Abstract
<p>Organic, biodynamic and conventional purple grape juices (PGJ; n = 79) produced in Brazil and Europe were characterized by volatile organic compounds (m/z 20-160) measured by proton transfer reaction mass spectrometry (PTR-MS), and classification models were built using supervised statistical techniques.k-Nearest neighbours and soft independent modelling of class analogy (SIMCA) models discriminated adequately the Brazilian from European PGJ (overall efficiency of 81% and 87%, respectively). Partial least squares discriminant analysis (PLSDA) classified 100% European and 96% Brazilian PGJ. Similarly, when samples were grouped as either conventional or organic/biodynamic, the PLSDA model classified 81% conventional and 83% organic/biodynamic juices. Intraregional PLSDA models (juices produced in the same region&nbsp;-&nbsp;either Europe or Brazil) were developed and were deemed accurate in discriminating Brazilian organic from conventional PGJ (81% efficiency), as well as European conventional from organic/biodynamic PGJ (94% efficiency).PGJ from Brazil and Europe, as well as conventional and organic/biodynamic PGJ, were distinguished with high efficiency, but no statistical model was able to differentiate organic and biodynamic grape juices. These data support the hypothesis that no clear distinction between organic and biodynamic grape juices can be made with respect to volatile organic compounds. &copy; 2014 Society of Chemical Industry.</p>
[1599] Blasioli, S., E. Biondi, D. Samudrala, F. Spinelli, A. Cellini, A. Bertaccini, S. M. Cristescu, and I. Braschi, "Identification of volatile markers in potato brown rot and ring rot by combined GC-MS and PTR-MS techniques: study on in vitro and in vivo samples.", J Agric Food Chem, vol. 62, pp. 337–347, Jan, 2014.
Link: http://dx.doi.org/10.1021/jf403436t
Abstract
<p>Ralstonia solanacearum (Rs) and Clavibacter michiganensis subsp. sepedonicus (Cms) are the bacterial causal agents of potato brown and ring rot, respectively, and are included in the A2 list of quarantine pathogens in Europe. Identification by GC-MS analysis of volatile organic compounds from Rs or Cms cultured on different nutrient media was performed. GC-MS and PTR-MS analysis were carried out also on unwounded potato tubers infected with the same pathogens. Infected tubers were produced by experimental inoculations of the plants. In in vitro experiments, Rs or Cms emitted volatile compounds, part of which were specific disease markers of potato (2-propanol and 3-methylbutanoic acid), mainly originating from bacterial metabolism (i.e., amino acid degradation, carbohydrate and fatty acid oxidation). In potato tubers, pathogen metabolism modified the volatile compound pattern emitted from healthy samples. Both bacteria seem to accelerate metabolic processes ongoing in potatoes and, in the case of Rs, disease markers (1-hepten-3-ol, 3,6-dimethyl-3-octanone, 3-ethyl-3-methylpentane, 1-chloroctane, and benzothiazole) were identified.</p>
[Papurello2014] Papurello, D., E. Schuhfried, A. Lanzini, A. Romano, L. Cappellin, T. D. Märk, S. Silvestri, and F. Biasioli, "Influence of co-vapors on biogas filtration for fuel cells monitored with PTR-MS (Proton Transfer Reaction-Mass Spectrometry)", Fuel processing technology, vol. 118: Elsevier, pp. 133–140, 2014.
Link: http://www.sciencedirect.com/science/article/pii/S0378382013002725
[1603] Beauchamp, J., M. Scheibe, T. Hummel, and A. Buettner, "Intranasal odorant concentrations in relation to sniff behavior.", Chem Biodivers, vol. 11, pp. 619–638, Apr, 2014.
Link: http://dx.doi.org/10.1002/cbdv.201300320
Abstract
<p>Knowledge on how odorants are transported through the nasal cavity to the olfactory epithelium is limited. One facet of this is how the sniffing behavior affects the abundance of odorants transferred to the olfactory cleft and in turn influences odor perception. A novel system that couples an online mass spectrometer with an odorant pulse delivery olfactometer was employed to characterize intranasal odorant concentrations of butane-2,3-dione (or butanedione, commonly known as diacetyl) at the interior naris and the olfactory cleft. Volunteers (n=12) were asked to perform different modes of sniffing in relation to the sniff intensity that were categorized as &#39;normal&#39;, &#39;rapid&#39; and &#39;forced&#39;. The highest concentrations of butanedione at both positions in the nose were observed during normal sniffing, with the lowest concentrations correlating with periods of forced sniffs. This corresponded to the panelists&#39; ratings that normal sniffing elicited the highest odor intensities. These feasibility assessments pave the way for more in-depth analyses with a variety of odorants of different chemical classes at various intranasal positions, to investigate the passage and uptake of odorants within the nasal cavity.</p>
[1604] Riva, M., R. M. Healy, P-M. Flaud, E. Perraudin, J. C. Wenger, and E. Villenave, "Kinetics of the gas-phase reactions of chlorine atoms with naphthalene, acenaphthene, and acenaphthylene.", J Phys Chem A, vol. 118, pp. 3535–3540, May, 2014.
Link: http://dx.doi.org/10.1021/jp5009434
Abstract
<p>Reactions of polycyclic aromatic hydrocarbons (PAHs) with chlorine atoms may occur in specific areas such as coastal regions and the marine boundary layer. In this work, rate constants for the gas-phase reactions of naphthalene, acenaphthene, and acenaphthylene with chlorine atoms have been measured using the relative rate technique. Experiments were performed at room temperature (293 &plusmn; 2 K) and atmospheric pressure in an atmospheric simulation chamber using a proton-transfer reaction mass spectrometer (PTR-MS) to monitor the concentrations of PAHs and the reference compounds (acetone, methanol, 1,3,5-trimethylbenzene, and isoprene) as a function of time. The rate constants obtained in this work were (in units of cm(3) molecule(-1) s(-1)) (4.22 &plusmn; 0.46) &times; 10(-12), (3.01 &plusmn; 0.82) &times; 10(-10), and (4.69 &plusmn; 0.82) &times; 10(-10) for naphthalene, acenaphthene, and acenaphthylene, respectively. These are the first measurements of the rate constants for gas-phase reactions of Cl atoms with acenaphthene and acenaphthylene. The rate constant determined in this study for the reaction of naphthalene with Cl atoms is not in agreement with the only other previously reported value in the literature. The results are used to assess the potential role of chlorine atom reactions in the atmospheric oxidation of PAHs.</p>

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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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PTR-MS Bibliography:

Lists with PTR-MS relevant publications of the University of Innsbruck;can be found at the websites of the Institute for Ion Physics and Applied Physics, workgroups: IMR, Environmental Physics and Nano-Bio-Physics

 

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