The world's leading PTR-MS company

Ultra-Sensitive Real-Time Trace Gas Analyzers  •  Modular TOF-MS for Research & OEM

Navigation

You are here

Scientific Articles - PTR-MS Bibliography

Welcome to the new IONICON scientific articles database!

Publications

Found 775 results
Title [ Year(Asc)]
2014
[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
[1705] Sánchez-López, J. A., R. Zimmermann, and C. Yeretzian, "Insight into the time-resolved extraction of aroma compounds during espresso coffee preparation: online monitoring by PTR-ToF-MS.", Anal Chem, vol. 86, pp. 11696–11704, Dec, 2014.
Link: http://dx.doi.org/10.1021/ac502992k
Abstract
<p>Using proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS), we investigated the extraction dynamic of 95 ion traces in real time (time resolution = 1 s) during espresso coffee preparation. Fifty-two of these ions were tentatively identified. This was achieved by online sampling of the volatile organic compounds (VOCs) in close vicinity to the coffee flow, at the exit of the extraction hose of the espresso machine (single serve capsules). Ten replicates of six different single serve coffee types were extracted to a final weight between 20-120 g, according to the recommended cup size of the respective coffee capsule (Ristretto, Espresso, and Lungo), and analyzed. The results revealed considerable differences in the extraction kinetics between compounds, which led to a fast evolution of the volatile profiles in the extract flow and consequently to an evolution of the final aroma balance in the cup. Besides exploring the time-resolved extraction dynamics of VOCs, the dynamic data also allowed the coffees types (capsules) to be distinguished from one another. Both hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed full separation between the coffees types. The methodology developed provides a fast and simple means of studying the extraction dynamics of VOCs and differentiating between different coffee types.</p>
[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>
[1564] Smith, D., P. Spanel, J. Herbig, and J. Beauchamp, "Mass spectrometry for real-time quantitative breath analysis", Journal of Breath Research, vol. 8, pp. 027101, Mar, 2014.
Link: http://dx.doi.org/10.1088/1752-7155/8/2/027101
Abstract
<p>Breath analysis research is being successfully pursued using a variety of analytical methods, prominent amongst which are gas chromatography with mass spectrometry, GC-MS, ion mobility spectrometry, IMS, and the fast flow and flow-drift tube techniques called selected ion flow tube mass spectrometry, SIFT-MS, and proton transfer reaction mass spectrometry, PTR-MS. In this paper the case is made for real-time breath analysis by obviating sample collection into bags or onto traps that can suffer from partial degradation of breath metabolites or the introduction of impurities. Real-time analysis of a broad range of volatile chemical compounds can be best achieved using SIFT-MS and PTR-MS, which are sufficiently sensitive and rapid to allow the simultaneous analyses of several trace gas metabolites in single breath exhalations. The basic principles and the ion chemistry that underpin these two analytical techniques are briefly described and the differences between them, including their respective strengths and weaknesses, are revealed, especially with reference to the analysis of the complex matrix that is exhaled breath. A recent innovation is described that combines time-of-flight mass spectrometry with the proton transfer flow-drift tube reactor, PTR-TOFMS, which provides greater resolution in the analytical mass spectrometer and allows separation of protonated isobaric molecules. Examples are presented of some recent data that well illustrate the quality and real-time feature of SIFT-MS and PTR-MS for the analysis of exhaled breath for physiological/biochemical/pharmacokinetics studies and for the identification and quantification of biomarkers relating to specific disease states.</p>
[1602] Smith, D., P. Spanel, J. Herbig, and J. Beauchamp, "Mass spectrometry for real-time quantitative breath analysis.", J Breath Res, vol. 8, pp. 027101, Jun, 2014.
Link: http://dx.doi.org/10.1088/1752-7155/8/2/027101
Abstract
<p>Breath analysis research is being successfully pursued using a variety of analytical methods, prominent amongst which are gas chromatography with mass spectrometry, GC-MS, ion mobility spectrometry, IMS, and the fast flow and flow-drift tube techniques called selected ion flow tube mass spectrometry, SIFT-MS, and proton transfer reaction mass spectrometry, PTR-MS. In this paper the case is made for real-time breath analysis by obviating sample collection into bags or onto traps that can suffer from partial degradation of breath metabolites or the introduction of impurities. Real-time analysis of a broad range of volatile chemical compounds can be best achieved using SIFT-MS and PTR-MS, which are sufficiently sensitive and rapid to allow the simultaneous analyses of several trace gas metabolites in single breath exhalations. The basic principles and the ion chemistry that underpin these two analytical techniques are briefly described and the differences between them, including their respective strengths and weaknesses, are revealed, especially with reference to the analysis of the complex matrix that is exhaled breath. A recent innovation is described that combines time-of-flight mass spectrometry with the proton transfer flow-drift tube reactor, PTR-TOFMS, which provides greater resolution in the analytical mass spectrometer and allows separation of protonated isobaric molecules. Examples are presented of some recent data that well illustrate the quality and real-time feature of SIFT-MS and PTR-MS for the analysis of exhaled breath for physiological/biochemical/pharmacokinetics studies and for the identification and quantification of biomarkers relating to specific disease states.</p>
[1596] Tanimoto, H., S. Kameyama, T. Iwata, S. Inomata, and Y. Omori, "Measurement of air-sea exchange of dimethyl sulfide and acetone by PTR-MS coupled with gradient flux technique.", Environ Sci Technol, vol. 48, pp. 526–533, Jan, 2014.
Link: http://dx.doi.org/10.1021/es4032562
Abstract
<p>We developed a new method for in situ measurement of air-sea fluxes of multiple volatile organic compounds (VOCs) by combining proton transfer reaction-mass spectrometry (PTR-MS) and gradient flux (GF) technique. The PTR-MS/GF system was first deployed to determine the air-sea flux of VOCs in the open ocean of the western Pacific, in addition to carbon dioxide and water vapor. Each profiling at seven heights from the ocean surface up to 14 m took 7 min. In total, 34 vertical profiles of VOCs in the marine atmosphere just above the ocean surface were obtained. The vertical gradient observed was significant for dimethyl sulfide (DMS) and acetone with the best-fit curves on quasi-logarithmic relationship. The mean fluxes of DMS and acetone were 5.5 &plusmn; 1.5 and 2.7 &plusmn; 1.3 μmol/m(2)/day, respectively. These fluxes are in general in accordance with those reported by previous expeditions.</p>
[1563] Silcock, P.., M.. Alothman, E.. Zardin, S.. Heenan, C.. Siefarth, P.J.. Bremer, and J.. Beauchamp, "Microbially induced changes in the volatile constituents of fresh chilled pasteurised milk during storage", Food Packaging and Shelf Life, vol. 2, pp. 81¬タモ90, Dec, 2014.
Link: http://dx.doi.org/10.1016/j.fpsl.2014.08.002
Abstract
<p>Off-odours caused by volatile organic compounds (VOCs) are often the first indicators consumers have of milk spoilage. In this study the VOCs associated with three types (trim, 0.25&ndash;0.40% fat; lite, 1.40&ndash;1.50% fat; and full-cream, 3.18&ndash;3.28% fat) of fresh chilled pasteurised milk (FCPM), held for up to 17 days at 4.5 &plusmn; 0.5 &deg;C, were measured using proton-transfer-reaction mass spectrometry (PTR-MS). The chemical identification of VOCs in the headspace of the milk was supported by SPME&ndash;GC&ndash;MS analysis. Bacterial numbers (aerobic plate count at 25 &deg;C) in the milk were also estimated. Replicate sets of milk types treated with sodium azide (NaN3) to inhibit microbial activity were investigated. The relationship between microbial numbers and VOCs was not linear; rather the concentrations of VOCs only started to change after a threshold number of bacteria ranging from 106&ndash;108 CFU mL&minus;1 was reached. This combined approach provided new insights on the effect of microbial growth on FCPM shelf-life.</p>
[1561] Beauchamp, J., E. Zardin, P. Silcock, and P. J. Bremer, "Monitoring photooxidation-induced dynamic changes in the volatile composition of extended shelf life bovine milk by PTR-{MS}", Journal of Mass Spectrometry, vol. 49, pp. 952–958, Sep, 2014.
Link: http://dx.doi.org/10.1002/jms.3430
Abstract
<p>Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf life (ESL) bovine milk samples were exposed to fluorescent light for up to 20 h at room temperature, and the volatiles in the samples&#39; headspace were measured in real time using proton-transfer-reaction mass spectrometry (PTR-MS). Compounds tentatively identified as methanethiol, acetone/propanal, pentanal/octanal/nonanal/1-octen-3-ol, hexanal, diacetyl, dimethyl disulphide, heptanal and benzaldehyde displayed dynamic release profiles relating to the changes occurring in milk upon exposure to light. Copyright &copy; 2014 John Wiley &amp; Sons, Ltd.</p>
[1722] "Omics in Soil Science", : Caister Academic Press, 2014.
Link: http://www.horizonpress.com/omics
Abstract
<p>Soil is a unique biological system with an abundant microflora and a very high microbial diversity capable of performing multiple key ecosystem functions. The detection of genes in soil has improved the knowledge of unculturable microorganisms and led to a greater understanding of potential soil metabolic pathways. Further advances in understanding soil functionality are being realised by harnessing omics technologies such as metagenomics, metatranscriptomics, proteomics and volatilomics. The next challenge of systems biology and functional genomics is to integrate the information from omic approaches to give a more complete picture of soil as a biological system. This volume presents the state-of-the-art of omic applications in soil science, a field that is advancing rapidly on many fronts. Distinguished authors describe the application of metagenomics, metatranscriptomics and proteomics to soil science. In particular the book covers the current and emerging omics techniques and the contribution of these approaches to a better assessment of soil functionality. The authors also explore the specific problems encountered in the application of various omics technologies to soil science and the future research requirements necessary to overcome the current limitations in this area. Topics covered include soil functional genomics, soil metagenomics, soil microbial ecology, soil metatranscriptomics, soil proteomics, soil volatilomics and soil proteogenomics. Omics techniques are also discussed in comparison with classical techniques. This book is both a practical guide and a recommended reference volume for all soil scientists.</p>
[1597] Szymczak, W., J. Rozman, V. Höllriegl, M. Kistler, S. Keller, D. Peters, M. Kneipp, H. Schulz, C. Hoeschen, M. Klingenspor, et al., "Online breath gas analysis in unrestrained mice by hs-PTR-MS.", Mamm Genome, vol. 25, pp. 129–140, Apr, 2014.
Link: http://dx.doi.org/10.1007/s00335-013-9493-8
Abstract
<p>The phenotyping of genetic mouse models for human disorders may greatly benefit from breath gas analysis as a noninvasive tool to identify metabolic alterations in mice. Phenotyping screens such as the German Mouse Clinic demand investigations in unrestrained mice. Therefore, we adapted a breath screen in which exhaled volatile organic compounds (VOCs) were online monitored by proton transfer reaction mass spectrometry (hs-PTR-MS). The source strength of VOCs was derived from the dynamics in the accumulation profile of exhaled VOCs of a single mouse in a respirometry chamber. A careful survey of the accumulation revealed alterations in the source strength due to confounders, e.g., urine and feces. Moreover changes in the source strength of humidity were triggered by changes in locomotor behavior as mice showed a typical behavioral pattern from activity to settling down in the course of subsequent accumulation profiles. We demonstrated that metabolic changes caused by a dietary intervention, e.g., after feeding a high-fat diet (HFD) a sample of 14 male mice, still resulted in a statistically significant shift in the source strength of exhaled VOCs. Applying a normalization which was derived from the distribution of the source strength of humidity and accounted for varying locomotor behaviors improved the shift. Hence, breath gas analysis may provide a noninvasive, fast access to monitor the metabolic adaptation of a mouse to alterations in energy balance due to overfeeding or fasting and dietary macronutrient composition as well as a high potential for systemic phenotyping of mouse mutants, intervention studies, and drug testing in mice.</p>
[1703] Timkovsky, J.., P.. Gankema, R.. Pierik, and R.. Holzinger, "A plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions.", Environ Sci Process Impacts, vol. 16, pp. 2301–2312, 2014.
Link: http://dx.doi.org/10.1039/c4em00214h
Abstract
<p>A system of two plant chambers and a downstream reaction chamber has been set up to investigate the emission of biogenic volatile organic compounds (BVOCs) and possible effects of pollutants such as ozone. The system can be used to compare BVOC emissions from two sets of differently treated plants, or to study the photochemistry of real plant emissions under polluted conditions without exposing the plants to pollutants. The main analytical tool is a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) which allows online monitoring of biogenic emissions and chemical degradation products. The identification of BVOCs and their oxidation products is aided by cryogenic trapping and subsequent in situ gas chromatographic analysis.</p>
[1643] Mochalski, P., K. Unterkofler, P. Spanel, D. Smith, and A. Amann, "Product ion distributions for the reactions of NO(+) with some physiologically significant aldehydes obtained using a SRI-TOF-MS instrument.", Int J Mass Spectrom, vol. 363, pp. 23–31, Apr, 2014.
Link: http://dx.doi.org/10.1016/j.ijms.2014.02.016
Abstract
<p>Product ion distributions for the reactions of NO(+) with 22 aldehydes involved in human physiology have been determined under the prevailing conditions of a selective reagent ionization time of flight mass spectrometry (SRI-TOF-MS) at an E/N in the flow/drift tube reactor of 130 Td. The chosen aldehydes were fourteen alkanals (the C2-C11 n-alkanals, 2-methyl propanal, 2-methyl butanal, 3-methyl butanal, and 2-ethyl hexanal), six alkenals (2-propenal, 2-methyl 2-propenal, 2-butenal, 3-methyl 2-butenal, 2-methyl 2-butenal, and 2-undecenal), benzaldehyde, and furfural. The product ion fragmentations patterns were determined for both dry air and humid air (3.5% absolute humidity) used as the matrix buffer/carrier gas in the drift tube of the SRI-TOF-MS instrument. Hydride ion transfer was seen to be a common ionization mechanism in all these aldehydes, thus generating (M-H)(+) ions. Small fractions of the adduct ion, NO(+)M, were also seen for some of the unsaturated alkenals, in particular 2-undecenal, and heterocyclic furfural for which the major reactive channel was non-dissociative charge transfer generating the M(+) parent ion. Almost all of the reactions resulted in partial fragmentation of the aldehyde molecules generating hydrocarbon ions; specifically, the alkanal reactions resulted in multiple product ions, whereas, the alkenals reactions produced only two or three product ions, dissociation of the nascent excited product ion occurring preferentially at the 2-position. The findings of this study are of particular importance for data interpretation in studies of aldehydes reactions employing SRI-TOF-MS in the NO(+) mode.</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>
[1565] Makhoul, S., A. Romano, L. Cappellin, G. Spano, V. Capozzi, E. Benozzi, T. D. Märk, 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--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>
[1609] Makhoul, S., A. Romano, L. Cappellin, G. Spano, V. Capozzi, E. Benozzi, T. D. Märk, 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.", J Mass Spectrom, vol. 49, pp. 850–859, 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&thinsp;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&thinsp;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.</p>
[1704] Yener, S., A. Romano, L. Cappellin, T. D. Märk, J. {Sánchez Del Pulgar}, F. Gasperi, L. Navarini, and F. Biasioli, "PTR-ToF-MS characterisation of roasted coffees (C. arabica) from different geographic origins.", J Mass Spectrom, vol. 49, pp. 929–935, Sep, 2014.
Link: http://dx.doi.org/10.1002/jms.3455
Abstract
<p>Characterisation of coffees according to their origins is of utmost importance for commercial qualification. In this study, the aroma profiles of different batches of three monoorigin roasted Coffea arabica coffees (Brazil, Ethiopia and Guatemala) were analysed by Proton-Transfer-Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS). The measurements were performed with the aid of a multipurpose autosampler. Unsupervised and supervised multivariate data analysis techniques were applied in order to visualise data and classify the coffees according to origin. Significant differences were found in volatile profiles of coffees. Principal component analysis allowed visualising a separation of the three coffees according to geographic origin and further partial least square regression-discriminant analysis classification showed completely correct predictions. Remarkably, the samples of one batch could be used as training set to predict geographic origin of the samples of the other batch, suggesting the possibility to predict further batches in coffee production by means of the same approach. Tentative identification of mass peaks aided characterisation of aroma fractions. Classification pinpointed some volatile compounds important for discrimination of coffees.</p>
[1606] Denzer, M. Y., S. Gailer, D. W. Kern, P. L Schumm, N. Thuerauf, J. Kornhuber, A. Buettner, and J. Beauchamp, "Quantitative Validation of the n-Butanol Sniffin' Sticks Threshold Pens.", Chemosens Percept, vol. 7, pp. 91–101, 2014.
Link: http://dx.doi.org/10.1007/s12078-014-9168-1
Abstract
<p>Odorant pens are used by medical practitioners and researchers to assess olfactory dysfunction. Despite their routine use, there are currently no data on the gas-phase odorant concentrations released from the pen tips or whether these concentrations scale linearly with the aqueous-phase concentrations inside the pens. The commercially available Sniffin&#39; Sticks odor threshold test containing n-butanol was chosen for evaluation. The gas-phase concentration of n-butanol at the tip of each pen was measured directly in a new set of pens via proton-transfer-reaction mass spectrometry (PTR-MS). Measurements were additionally made on the same pens after 6&nbsp;months and two older pen sets, namely a 3-year-old (used) and 4-year-old (new) set. Furthermore, application-related tests were made to determine the performance of the pens during routine use and under stress. These data demonstrate that the gas-phase n-butanol concentrations of the threshold pens are linear over the entire set, both for brand-new pens and 6&nbsp;months later; this reflects the expected performance that was previously only assumed. Furthermore, the application-simulation tests demonstrated a good performance of the pens when used according to their intended protocol. Measurements of the older pen sets suggest that storage conditions are more critical than usage for pen stability. The present findings confirm that the n-butanol odorant pens are an appropriate tool for threshold testing, provided they are stored and handled correctly.</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>
[1665] Yanagisawa, N., "Results of on-line measurement of organic compounds adsorbed on diesel exhaust particles by PTR-TOFMS", (Poster) 18th ETH Conference on Combustion Generated Nanoparticles, vol. 18, June, 2014.
Link: http://www.nanoparticles.ch/2014_ETH-NPC-18/Yanagisawa.pdf
Abstract
Organic compounds in particle-phase of diesel emission are of interest in view of particle nature and origin. In this work, particle‐phase organic compounds from a modern diesel engine were analyzed using on-line PTR‐TOFMS (Proton Transfer Reaction – Time of Flight Mass Spectrometer). To analyze particle-phase organic compounds, sampled exhaust was passed through a heating tube upstream of PTR-TOFMS. The results show that higher molecular weight compounds had higher portion in particle-phase and concentration changes corresponded to operating condition change of the engine.
[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>
[1723] Insam, H., "Soil volatile organic compounds as tracers for microbial activities in soils", Omics in Soil Science: Caister Academic Press, pp. 127–138, 2014.
Link: http://www.horizonpress.com/omics
[1759] Greenberg, J.. P., J.. Penuelas, A.. Guenther, R.. Seco, A.. Turnipseed, X.. Jiang, I.. Filella, M.. Estiarte, J.. Sardans, R.. Ogaya, et al., "A tethered-balloon PTRMS sampling approach for surveying of landscape-scale biogenic VOC fluxes", Atmospheric Measurement Techniques, vol. 7, pp. 2263–2271, Jul, 2014.
Link: http://dx.doi.org/10.5194/amt-7-2263-2014
Abstract
<p>To survey landscape-scale fluxes of biogenic gases, a 100 m Teflon tube was attached to a tethered balloon as a sampling inlet for a fast response Proton Transfer Reaction Mass Spectrometer (PTRMS). Along with meteorological instruments deployed on the tethered balloon and at 3 m and outputs from a regional weather model, these observations were used to estimate landscape scale biogenic volatile organic compound fluxes with two micrometeorological techniques: mixed layer variance and surface layer gradients. This highly mobile sampling system was deployed at four field sites near Barcelona to estimate landscape-scale BVOC emission factors in a relatively short period (3 weeks). The two micrometeorological techniques agreed within the uncertainty of the flux measurements at all four sites even though the locations had considerable heterogeneity in species distribution and complex terrain. The observed fluxes were significantly different than emissions predicted with an emission model using site-specific emission factors and land-cover characteristics. Considering the wide range in reported BVOC emission factors of VOCs for individual vegetation species (more than an order of magnitude), this flux estimation technique is useful for constraining BVOC emission factors used as model inputs.</p>

Pages

Featured Articles

Download Contributions to the International Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications:

 

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).
Link

J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257.
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.
Link

 

Lists with PTR-MS relevant publications of the University of Innsbruck can be found here: Atmospheric and indoor air chemistry, IMR, Environmental Physics and Nano-Bio-Physics

 

Download the latest version of the IONICON publication database as BibTeX.