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Scientific Articles - PTR-MS Bibliography

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Found 646 results
Title [ Year(Asc)]
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, vol. 30, issue 2, pp. n/a–n/a, 01/2014.
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>
[1558] 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>
[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>
[1564] 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¬タモ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>
[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>
[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>
[1556] Sukul, P., P. Trefz, J. K. Schubert, and W. Miekisch, "Immediate effects of breath holding maneuvers onto composition of exhaled breath", Journal of Breath Research, vol. 8, pp. 037102, Sep, 2014.
Link: http://dx.doi.org/10.1088/1752-7155/8/3/037102
Abstract
<p>Rapid concentration changes due to physiological or pathophysiological effects rather than appearance of unique disease biomarkers are important for clinical application of breath research. Simple maneuvers such as breath holding may significantly affect breath biomarker concentrations. In this study, exhaled volatile organic compound (VOC) concentrations were assessed in real time before and after different breath holding maneuvers. Continuous breath-resolved measurements (PTR-ToF-MS-8000) were performed in 31 healthy human subjects in a side-stream sampling mode. After 1 min of tidal breathing participants held their breath for 10, 20, 40, 60 s and as long as possible. Afterwards they continued to breathe normally for another minute. VOC profiles could be monitored in real time by assigning online PTR-ToF-MS data to alveolar or inspired phases of breath. Sudden and profound changes of exhaled VOC concentrations were recorded after different breath holding maneuvers. VOC concentrations returned to base line levels 10&ndash;20 s after breath holding. Breath holding induced concentration changes depended on physico-chemical properties of the substances. When substance concentrations were normalized onto end-tidal CO2 content, variation of acetone concentrations decreased, whereas variations of isoprene concentrations were not affected. As the effects of breathing patterns on exhaled substance concentrations depend on individual substance properties, sampling procedures have to be validated for each compound by means of appropriate real-time analysis. Normalization of exhaled concentrations onto exhaled CO2 is only valid for substances having similar physico-chemical properties as CO2.</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
[1562] 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><span style="color: rgb(0, 0, 0); font-family: Arial, Helvetica, Verdana, sans-serif; font-size: 12px; line-height: 16.2000007629395px; background-color: rgb(255, 255, 255);">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.</span></p>
[1561] 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>
[1559] 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>
[1551] Brilli, F., B. Gioli, P. Ciccioli, D. Zona, F. Loreto, I. A. Janssens, and R. Ceulemans, "Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-TOF-MS) determination of volatile organic compounds (VOCs) emitted from a biomass fire developed under stable nocturnal conditions", Atmospheric Environment, vol. 97, pp. 54 - 67, 2014.
Link: http://www.sciencedirect.com/science/article/pii/S1352231014006013
Abstract
<p>Abstract Combustion of solid and liquid fuels is the largest source of potentially toxic volatile organic compounds (VOCs), which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction &ldquo;Time-of-Flight&rdquo; Mass Spectrometer (PTR-TOF-MS), which couples high sensitivity with high mass resolution, for real-time detection of multiple \{VOCs\} emitted by burned hay and straw in a barn located near our measuring station. We detected 132 different organic ions directly attributable to \{VOCs\} emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the \{VOC\} mixture composition. The time-course of the 25 most abundant VOCs, representing &sim;85% of the whole mixture of VOCs, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic \{VOC\} and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of \{ER\} (and EF) were overestimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant \{VOCs\} in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, the evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic gases recorded.</p>
[1533] Sulzer, P., E. Hartungen, G. Hanel, S. Feil, K. Winkler, P. Mutschlechner, S. Haidacher, R. Schottkowsky, D. Gunsch, H. Seehauser, et al., "A Proton Transfer Reaction-Quadrupole interface Time-Of-Flight Mass Spectrometer (PTR-QiTOF): High speed due to extreme sensitivity", International Journal of Mass Spectrometry, vol. 368, pp. 1-5, 2014.
Link: http://www.sciencedirect.com/science/article/pii/S1387380614001584
Abstract
<p>Here we introduce a new prototype of a Proton Transfer Reaction-Time-Of-Flight Mass Spectrometry (PTR-TOFMS) instrument. In contrast to commercially available PTR-TOFMS devices so far, which utilize a transfer lens system, the novel prototype is equipped with a quadrupole ion guide for the highly effective transfer of ions from the drift tube to the mass spectrometer; hence we call it PTR-QiTOF, whereas &ldquo;Qi&rdquo; stands for &ldquo;Quadrupole interface&rdquo;. This new interface greatly improves the TOF mass resolution because of favorable injection conditions. Depending on whether we optimize the PTR-QiTOF to maximum sensitivity or maximum mass resolution, we get about 6900 and 10,400 m/m mass resolution, respectively, already at m/z 149 (increasing with ascending masses). Furthermore, we increase the pressure in the drift tube from typically 2.2 mbar to 3.8 mbar and the drift tube voltage from 600V to 1000 V. We directly compare the sensitivities of a commercial state-of-the-art PTR-TOFMS instrument to this &ldquo;high pressure&rdquo; PTR-QiTOF prototype and find that these modifications lead to a gain on average by a factor of 25 in terms of sensitivity with a maximum of about 4700 cps/ppbv for dichlorobenzene atm/z 147 for the PTR-QiTOF. This is (to our knowledge) the highest sensitivity ever reported for a PTR-MS instrument, regardless of the employed mass spectrometer. The increased sensitivity also has a very positive effect on the detection limit, which lies now at about 20 pptv with 100ms and 750 ppqv after 1 min integration time.Weprovide data on the linearity of the instrumental response over a concentration range of five orders of magnitude and evaluate the prototype&rsquo;s performance in a real-life test by analyzing the dynamic headspace of a minute amount of trinitrotoluene using only 2 s integration time.</p>
[1563] Makhoul, S., A. Romano, L. Cappellin, G. Spano, V. Capozzi, E. Benozzi, T. D. Mᅢᄂrk, E. Aprea, F. Gasperi, H. El-Nakat, et al., "Proton-transfer-reaction mass spectrometry for the study of the production of volatile compounds by bakery yeast starters", Journal of Mass Spectrometry, vol. 49, pp. 850¬タモ859, Sep, 2014.
Link: http://dx.doi.org/10.1002/jms.3421
Abstract
<p>The aromatic impact of bakery yeast starters is currently receiving considerable attention. The flavor characteristics of the dough and the finished products are usually evaluated by gas chromatography and sensory analysis. The limit of both techniques resides in their low-throughput character. In the present work, proton-transfer-reaction mass spectrometry (PTR-MS), coupled to a time-of-flight mass analyzer, was employed, for the first time, to measure the volatile fractions of dough and bread, and to monitor Saccharomyces cerevisiae volatile production in a fermented food matrix. Leavening was performed on small-scale (1 g) dough samples inoculated with different commercial yeast strains. The leavened doughs were then baked, and volatile profiles were determined during leavening and after baking. The experimental setup included a multifunctional autosampler, which permitted the follow-up of the leavening process on a small scale with a typical throughput of 500 distinct data points in 16 h. The system allowed to pinpoint differences between starter yeast strains in terms of volatile emission kinetics, with repercussions on the final product (i.e. the corresponding micro-loaves). This work demonstrates the applicability of PTR-MS for the study of volatile organic compound production during bread-making, for the automated and online real-time monitoring of the leavening process, and for the characterization and selection of bakery yeast starters in view of their production of volatile compounds. Copyright &copy; 2014 John Wiley &amp; Sons, Ltd.</p>
[1468] Luchner, M., T. Schmidberger, and G. Striedner, "Real-Time Approach", European Biopharmaceutical Review, vol. 1, pp. 52–55, 01/2014.
Link: http://edition.pagesuite-professional.co.uk/Launch.aspx?PBID=587773cf-29c4-46f2-9d9d-2f87bf178b5c
Abstract
<p>The complexity of using living cells as production system for modern biopharmaceuticals represents a major challenge in bioprocess design and control. Real-time access to relevant process variables is limited - however, proton transfer reaction mass spectrometers hold great potential to change this.</p>
[1523] Herbig, J.., R.. Gutmann, K.. Winkler, A.. Hansel, and G.. Sprachmann, "Real-Time Monitoring of Trace Gas Concentrations in Syngas", Oil Gas Sci. Technol. Rev. IFP Energies nouvelles, vol. 69, pp. 363–372, August, 2014.
Link: http://ogst.ifpenergiesnouvelles.fr/articles/ogst/abs/2014/02/ogst120243/ogst120243.html
Abstract
<p>EN: A Proton Transfer Reaction Mass Spectrometer (PTR-MS) was used for the analysis of syngas in an industrial Fischer-Tropsch process. A PTR-MS can detect a variety of volatile organic and inorganic compounds in real-time and with high sensitivity. Together with a multiplexer, this allows for online (real-time) monitoring of the trace contaminations at different stages of a Fischer-Tropsch process. Several volatile compounds, such as HCN, H2S, RSH, carbonyls, acids, alcohols and others have been measured in Syngas. This paper describes the setup to monitor syngas using PTR-MS and summarizes the result of this proof-of-principle project. FR: Un spectromètre de masse par réaction de transfert de protons (PTR-MS, Proton Transfer Reaction &ndash; Mass Spectrometer) a été utilisé pour l&rsquo;analyse de gaz de synthèse dans un procédé industriel Fischer-Tropsch. Un PTR-MS peut détecter une grande variété de composés organiques et inorganiques volatils en temps réel et avec une sensibilité élevée. Associé à un multiplexeur, il permet un suivi en ligne (en temps réel) des contaminants à l&rsquo;état de traces à différents stades d&rsquo;un procédé Fischer-Tropsch. Plusieurs composés volatils, tels que HCN, H2S, RSH, des carbonyles, des acides, des alcools et autres, ont été mesurés dans du gaz de synthèse. Cet article décrit la configuration pour le suivi du gaz de synthèse en utilisant le PTR-MS et résume le résultat de ce projet de preuve de concept.</p>
[1557] Feilberg, A., "Reduced odour from pig farms", PROFILE 2013 Department OF Engineering: Aarhus University, 2014.
Link: http://www.e-pages.dk/aarhusuniversitet/827/
Abstract
<p>An innovative new ventilation system will help Danish livestock production to cope with more of the environmental challenges that the industry is facing.</p>
[1521] Brilli, F., B. Gioli, D. Zona, E. Pallozzi, T. Zenone, G. Fratini, C. Calfapietra, F. Loreto, I. A. Janssens, and R. Ceulemans, "Simultaneous leaf- and ecosystem-level fluxes of volatile organic compounds from a poplar-based SRC plantation", Agricultural and Forest Meteorology, vol. 187, pp. 22–35, Apr, 2014.
Link: http://dx.doi.org/10.1016/j.agrformet.2013.11.006
Abstract
<p>Emission of carbon from ecosystems in the form of volatile organic compounds (VOC) represents a minorcomponent flux in the global carbon cycle that has a large impact on ground-level ozone, particle andaerosol formation and thus on air chemistry and quality. This study reports exchanges of CO2and VOCbetween a poplar-based short rotation coppice (SRC) plantation and the atmosphere, measured simul-taneously at two spatial scale, one at stand level and another at leaf level. The first technique combinedProton Transfer Reaction &ldquo;Time-of-Flight&rdquo; mass spectrometry (PTR&ndash;TOF&ndash;MS) with the eddy covariancemethod, to measure fluxes of a multitude of VOC. Abundant fluxes of isoprene, methanol and, to a lesserextent, fluxes of other oxygenated VOC such as formaldehyde, isoprene oxidation products (methyl vinylketone and methacrolein), methyl ethyl ketone, acetaldehyde, acetone and acetic acid, were measured.Under optimal environmental conditions, isoprene flux was mostly controlled by temperature and light.Differently, methanol flux underwent a combined enzymatic and stomatal control, together involvingenvironmental drivers such as vapour pressure deficit (VPD), temperature and light intensity. Moreoverfair weather condition favoured ozone deposition to the poplar plantation.The second technique involved trapping the VOCs emitted from leaves followed by gaschromatography-mass spectrometry (GC&ndash;MS) analysis. These leaf-level measurements showed thatemission of isoprene in adult leaves and of monoterpenes in juvenile leaves are widespread across poplargenotypes. Detection of isoprene oxidation products (iox) emission with leaf-level measurements con-firmed that a fraction of isoprene may be already oxidized within leaves, possibly when isoprene copeswith foliar reactive oxygen species (ROS) formed during warm and sunny days.</p>
[1529] Platt, S.M.., I.E.. Haddad, S.M.. Pieber, R.-J.. Huang, A.A.. Zardini, M.. Clairotte, R.. Suarez-Bertoa, P.. Barmet, L.. Pfaffenberger, R.. Wolf, et al., "Two-stroke scooters are a dominant source of air pollution in many cities", Nature Communications, vol. 5, May, 2014.
Link: http://dx.doi.org/10.1038/ncomms4749
Abstract
<p>Fossil fuel-powered vehicles emit significant particulate matter, for example, black carbon and primary organic aerosol, and produce secondary organic aerosol. Here we quantify secondary organic aerosol production from two-stroke scooters. Cars and trucks, particularly diesel vehicles, are thought to be the main vehicular pollution sources. This needs re-thinking, as we show that elevated particulate matter levels can be a consequence of &lsquo;asymmetric pollution&rsquo; from two-stroke scooters, vehicles that constitute a small fraction of the fleet, but can dominate urban vehicular pollution through organic aerosol and aromatic emission factors up to thousands of times higher than from other vehicle classes. Further, we demonstrate that oxidation processes producing secondary organic aerosol from vehicle exhaust also form potentially toxic &lsquo;reactive oxygen species&rsquo;.</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.
Link

W. Lindinger, A. Hansel, A. Jordan: Proton-transfer-reaction mass spectrometry (PTR–MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev. 27 (1998), 347-375.
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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

 

Our searchable publications database, hosted and updated by IONICON, predominately covers the application areas of instrumentation, technology, environmental research and food & flavor science, but is open to all PTR-MS related topics and we're looking for your results! Please submit your abstract.

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