[Zini2005] "QTL mapping of volatile compounds in ripe apples detected by proton transfer reaction-mass spectrometry",
, vol. 145, no. 3: Springer, pp. 269–279, 2005.
The availability of genetic linkage maps enables the detection and analysis of QTLs contributing to quality traits of the genotype. Proton Transfer Reaction Mass Spectrometry (PTR-MS), a relatively novel spectrometric technique, has been applied to measure the headspace composition of the Volatile Organic Compounds (VOCs) emitted by apple fruit genotypes of the progeny ‘Fiesta’ × ‘Discovery’. Fruit samples were characterised by their PTR-MS spectra normalised to total area. QTL analysis for all PTR-MS peaks was carried out and 10 genomic regions associated with the peaks at m/z = 28, 43, 57, 61, 103, 115 and 145 were identified (LOD > 2.5). We show that it is possible to find quantitative trait loci (QTLs) related to PTR-MS characterisation of the headspace composition of single whole apple fruits indicating the presence of a link between molecular characterisation and PTR-MS data. We provide tentative information on the metabolites related to the detected QTLs based on available chemical information. A relation between apple skin colour and peaks related to carbonyl compounds was established.
[Costa2013] "QTL validation and stability for volatile organic compounds (VOCs) in apple.",
, vol. 211: n Edmund Mach, Via Mach 1, 38010 San Michele all'Adige (TN), Italy. Electronic address: email@example.com., pp. 1–7, Oct, 2013.
The aroma trait in apple is a key factor for fruit quality strongly affecting the consumer appreciation, and its detection and analysis is often an extremely laborious and time consuming procedure. Molecular markers associated to this trait can to date represent a valuable selection tool to overcome these limitations. QTL mapping is the first step in the process of targeting valuable molecular markers to be employed in marker-assisted breeding programmes (MAB). However, a validation step is usually required before a newly identified molecular marker can be implemented in marker-assisted selection. In this work the position of a set of QTLs associated to volatile organic compounds (VOCs) was confirmed and validated in three different environments in Switzerland, namely Wädenswil, Conthey and Cadenazzo, where the progeny 'Fiesta×Discovery' was replicated. For both QTL identification and validation, the phenotypic data were represented by VOCs produced by mature apple fruit and assessed with a Proton Transfer Reaction-Mass Spectrometer (PTR-MS) instrument. The QTL-VOC combined analysis performed among these three locations validated the presence of important QTLs in three specific genomic regions, two located in the linkage group 2 and one in linkage group 15, respectively, for compounds related to esters (m/z 43, 61 and 131) and to the hormone ethylene (m/z 28). The QTL set presented here confirmed that in apple some compounds are highly genetically regulated and stable across environments.
[Brilli2012] "Qualitative and quantitative characterization of volatile organic compound emissions from cut grass.",
Environ Sci Technol
, vol. 46, no. 7: Ionicon Analytik GmbH, Eduard-Bodem-Gasse 3, 6020 Innsbruck, Austria., pp. 3859–3865, Apr, 2012.
Mechanical wounding of plants triggers the release of a blend of reactive biogenic volatile organic compounds (BVOCs). During and after mowing and harvesting of managed grasslands, significant BVOC emissions have the potential to alter the physical and chemical properties of the atmosphere and lead to ozone and aerosol formation with consequences for regional air quality. We show that the amount and composition of BVOCs emitted per unit dry weight of plant material is comparable between laboratory enclosure measurements of artificially severed grassland plant species and in situ ecosystem-scale flux measurements above a temperate mountain grassland during and after periodic mowing and harvesting. The investigated grassland ecosystem emitted annually up to 130 mg carbon m(-2) in response to cutting and drying, the largest part being consistently represented by methanol and a blend of green leaf volatiles (GLV). In addition, we report the plant species-specific emission of furfural, terpenoid-like compounds (e.g., camphor), and sesquiterpenes from cut plant material, which may be used as tracers for the presence of given plant species in the ecosystem.
 "Quality changes during storage of cooked and sliced meat products measured with PTR-MS and HS-GC-MS.",
, vol. 95, pp. 302–310, Oct, 2013.
<p>The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography-mass spectrometry (HS-GC-MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC-MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.</p>
[Jaksch2004a] "Quality control of a herb extract using PTR-MS",
International Journal of Mass Spectrometry
, vol. 239, no. 2: Elsevier, pp. 203–207, 2004.
We have developed an objective method for the determination of a herb extract's quality based on headspace measurements by proton-transfer-reaction mass spectrometry (PTR-MS); this quality was checked by a sensory analysis until now. This novel method enables the company ‘Bionorica’ to ensure that they are only selling high-quality products and therefore avoid complaints of the customer. The method could be also used for controlling and optimising the production process.
[Knighton2007] "Quantification of aircraft engine hydrocarbon emissions using proton transfer reaction mass spectrometry",
Journal of Propulsion and Power
, vol. 23, no. 5, pp. 949–958, 2007.
[Kreuzwieser2003] "Quantification of carbon sources for isoprene emission in poplar leaves",
AGU Fall Meeting Abstracts
, vol. 1, pp. 0119, 2003.
Isoprene is the most abundant volatile organic compound emitted by plants and in particular by trees. Current interest in understanding its biosynthesis in chloroplasts is forced by the important role isoprene plays in atmospheric chemistry. Leaf isoprene formation is closely linked to photosynthesis by a dynamic use of recently fixed photosynthetic precursors in the chloroplast. Under steady state conditions in [13C]CO2 atmosphere approximately 75 % of isoprene became labeled within minutes. The source of unlabeled C is suggested to be of extra-chloroplastidic and/or from starch degradation. In order to test whether these alternative carbon sources - leaf internal C-pools and xylem-transported carbohydrates, contribute to leaf isoprene formation in poplar (Populus tremula x P. alba) on-line proton-transfer-reaction-mass spectrometry (PTR-MS) was used to follow 13C-labeling kinetics.
[Zhao2004] "Quantification of hydroxycarbonyls from OH-isoprene reactions.",
J Am Chem Soc
, vol. 126, no. 9: M University, College Station, Texas 77843, USA. firstname.lastname@example.org, pp. 2686–2687, Mar, 2004.
Hydroxycarbonyls arising from OH-initiated reactions of isoprene have been quantified by the technique of a flow reactor coupled to proton-transfer reaction mass spectrometry (PTR-MS) detection. The yields of C5- and C4-hydroxycarbonyls are (19.3 +/- 6.1)% and (3.3 +/- 1.6)%, respectively, measured at a flow tube pressure of about 100 Torr and at a temperature of 298 +/- 2 K. A yield of (8.4 +/- 2.4)% is obtained for the unsaturated carbonyl C5H8O, confirming that internal OH addition represents the minor channel in the initial OH-isoprene reaction. The results show that those carbonyl compounds account for the most previously unquantified carbon, enabling the isoprene carbon closure. The study also reveals novel aspects of the delta-hydroxyalkoxy radical degradation mechanism, which is essential for modeling tropospheric O3 formation. In addition, this work demonstrates the application of PTR-MS for quantification of products of hydrocarbon reactions, which should have profound impacts on elucidation of the chemistry of atmospheric anthropogenic and biogenic hydrocarbons.
[Joo2010a] "Quantification of interferences in PTR-MS measurements of monoterpene emissions from Fagus sylvatica L. using simultaneous TD-GC-MS measurements",
International Journal of Mass Spectrometry
, vol. 291, no. 1: Elsevier, pp. 90–95, 2010.
The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions stems from their importance in atmospheric chemistry. In order to compare the most frequently used BVOC measurement techniques, simultaneous on-line PTR-MS and off-line GC-MS data collection was performed on a 3 years old Fagus sylvatica L. tree placed in a growth chamber. Using an internal standard (deuterated toluene) and applying the selective ion mode (SIM) resulted in significant improvements of monoterpene (MT) quantification by TD-GC-MS. PTR-MS quantification of MTs was based on the ion signal at m/z 137. In the course of the experiments the relative contribution of linalool compared to that of MTs was found to be up to 84%. Since this compound has also a PTR-MS signature at m/z 137, quantification of MT emission rates by PTR-MS was disturbed. Comparison of GC-MS and PTR-MS data allowed an estimation of the ratio of the PTR-MS sensitivity for linalool to the one for MTs at m/z 137. This ratio of sensitivities, combined with the information of the relative contribution of linalool to the sum of linalool and MTs obtained by GC-MS, resulted in accurate derivation of the sum of emission rates of linalool and MTs by PTR-MS. The results indicate that fast and on-line PTR-MS measurements of BVOCs are best accompanied by off-line GC measurements to detect possible interferences or to use the additional information for properly quantifying the sum of emission rates of several compounds.
[Beale2011] "Quantification of oxygenated volatile organic compounds in seawater by membrane inlet-proton transfer reaction/mass spectrometry.",
Anal Chim Acta
, vol. 706, no. 1: Plymouth Marine Laboratory, Plymouth, Devon, UK. email@example.com, pp. 128–134, Nov, 2011.
The role of the ocean in the cycling of oxygenated volatile organic compounds (OVOCs) remains largely unanswered due to a paucity of datasets. We describe the method development of a membrane inlet-proton transfer reaction/mass spectrometer (MI-PTR/MS) as an efficient method of analysing methanol, acetaldehyde and acetone in seawater. Validation of the technique with water standards shows that the optimised responses are linear and reproducible. Limits of detection are 27 nM for methanol, 0.7 nM for acetaldehyde and 0.3 nM for acetone. Acetone and acetaldehyde concentrations generated by MI-PTR/MS are compared to a second, independent method based on purge and trap-gas chromatography/flame ionisation detection (P&T-GC/FID) and show excellent agreement. Chromatographic separation of isomeric species acetone and propanal permits correction to mass 59 signal generated by the PTR/MS and overcomes a known uncertainty in reporting acetone concentrations via mass spectrometry. A third bioassay technique using radiolabelled acetone further supported the result generated by this method. We present the development and optimisation of the MI-PTR/MS technique as a reliable and convenient tool for analysing seawater samples for these trace gases. We compare this method with other analytical techniques and discuss its potential use in improving the current understanding of the cycling of oceanic OVOCs.
[Prazeller1998] "Quantification of passive smoking using proton-transfer-reaction mass spectrometry",
International journal of mass spectrometry
, vol. 178, no. 3: Elsevier, pp. L1–L4, 1998.
[Lirk2004] "Quantification of recent smoking behaviour using proton transfer reaction-mass spectrometry (PTR-MS).",
Wien Klin Wochenschr
, vol. 116, no. 1-2: Department of Anesthesiology and Critical Care Medicine, Clinical Division of General Internal Medicine, Leopold-Franzens University, Innsbruck, Austria., pp. 21–25, Jan, 2004.
Smoking is the most important single risk factor in current public health. Surveillance of exposure to tobacco smoke may be accomplished using environmental monitoring or in-vivo tests for smoking biomarkers. Acetonitrile exhaled in human breath has been described as a potential marker mirroring recent smoking behavior. The aim of this study was to determine exhaled acetonitrile levels in a sample of 268 volunteers (48 smokers, 220 non-smokers) attending a local health fair. Breath specimens were collected into inert sample bags, with parallel collection of ambient air. Subsequently, all samples were analysed using proton transfer reaction-mass spectrometry (PTR-MS). Smokers had elevated levels of exhaled acetonitrile compared with non-smokers (p<0.001). Analysis using the receiver-operating-characteristic curve demonstrated that smoking can be predicted with a sensitivity of 79% and a specificity of 91%, using a cut-off concentration of 20.31 parts per billion of acetonitrile. This first field survey of exhaled acetonitrile in a large group of test persons demonstrates the feasibility of a rapid and non-invasive test for recent exposure to tobacco. We conclude that analysis of exhaled-breath acetonitrile may serve as a method of determining recent active smoking behaviour.
[Schoberberger2004] "Quantification of recent smoking behaviour using Proton Transfer Reaction-Mass Spectrometry (PTR-MS).",
Wien Klin Wochenschr
, vol. 116, no. 5-6, pp. 209; author reply 209–209; author reply 210, Mar, 2004.
Heutzutage gilt Rauchen als der wichtigste medizinische Risikofaktor. Die Überwachung einer Exposition gegenüber Tabakrauch kann im Prinzip mittels Umluftmessungen, oder direkt mit Hilfe von Biomarkern erfolgen. Acetonitrile wurde als ein potentieller Marker für das rezente Raucherverhalten beschrieben. Es war daher das Ziel vorliegender Studie, die in der Ausatemluft festgestellten Acetonitrile-Konzentrationen in einem Kollektiv von 268 Personen (48 Raucher, 220 Nichtraucher) festzustellen. Atemgasproben wurden in inerten Sammelgefäßen gesammelt, und die Konzentration von Acetonitrile in der Umluft während der Abnahmen wurde parallel erhoben. Die Analyse der Umluft- und Atemluftproben erfolgte mittels Protonen Transfer Reaktions-Massenspektrometrie (PTR-MS). Raucher zeigten in der Ausatemluft signifikant erhöhte Acetonitrilekonzentrationen im Vergleich zu Nichtrauchern (p<0,001). Die Erstellung einer receiver-operating-characteristic curve ergab für die Unterscheidung von Rauchern und Nichtrauchern mittels PTR-MS eine Sensitivität von 79% und eine Spezifität von 91% bei einem Schwellenwert von 20.31 parts per billion. Diese erste Feldstudie zum Thema Acetonitrile in einem großen Testkollektiv konnte die Praktikabilität dieses Markers als schnellen und nichtinvasiven Test rezenten Raucherverhaltens nachweisen. Wir schlussfolgern, dass die Analyse der Atemgaskonzentration von Acetonitrile Rückschlüsse auf das aktive Raucherverhalten ziehen lässt.
[Bouvier-Brown2007] "Quantifying sesquiterpene and oxygenated terpene emissions from live vegetation using solid-phase microextraction fibers.",
J Chromatogr A
, vol. 1161, no. 1-2: University of California, Berkeley, CA, USA. firstname.lastname@example.org, pp. 113–120, Aug, 2007.
Biogenic terpenes play important roles in ecosystem functioning and atmospheric chemistry. Some of these compounds are semi-volatile and highly reactive, such as sesquiterpenes and oxygenated terpenes, and are thus difficult to quantify using traditional air sampling and analysis methods. We developed an alternative approach to quantify emissions from live branches using a flow through enclosure and sample collection on solid-phase microextraction (SPME) fibers. This method allows for collection and analysis of analytes with minimal sample transfer through tubing to reduce the potential for losses. We characterized performance characteristics for 65 microm polydimethylsiloxane-divinylbenzene (PDMS/DVB) fibers using gas chromatography followed by mass spectrometry and optimized experimental conditions and procedures for field collections followed by laboratory analysis. Using 10-45 min sampling times and linear calibration curves created from mixtures of terpenes, emissions of methyl chavicol, an oxygenated terpene, and an array of sesquiterpenes were quantified from a Ponderosa pine branch. The detection limit was 4.36 pmol/mol (ppt) for methyl chavicol and 16.6 ppt for beta-caryophyllene. Concentrations determined with SPME fibers agreed with measurements made using proton transfer reaction mass spectrometry (PTR-MS) within the estimated error of the method for well calibrated compounds. This technique can be applied for quantification of biogenic oxygenated terpene and sesquiterpene emissions from live branches in the field.
[Maerk2006] "Quantitation of furan and methylfuran formed in different precursor systems by proton transfer reaction mass spectrometry.",
J Agric Food Chem
, vol. 54, no. 7: NestlÃ© Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland., pp. 2786–2793, Apr, 2006.
Furan has recently received attention as a possibly hazardous compound occurring in certain thermally processed foods. Previous model studies have revealed three main precursor systems producing furan upon thermal treatment, i.e., ascorbic acid, Maillard precursors, and polyunsaturated lipids. We employed proton transfer reaction mass spectrometry (PTR-MS) as an on-line monitoring technique to study furan formation. Unambiguous identification and quantitation in the headspace was achieved by PTR-MS/gas chromatography-mass spectrometry coupling. Ascorbic acid showed the highest potential to generate furan, followed by glyceryl trilinolenate. Some of the reaction samples generated methylfuran as well, such as Maillard systems containing alanine and threonine as well as lipids based on linolenic acid. The furan yields from ascorbic acid were lowered in an oxygen-free atmosphere (30%) or in the presence of reducing agents (e.g., sulfite, 60%), indicating the important role of oxidation steps in the furan formation pathway. Furthermore, already simple binary mixtures of ascorbic acid and amino acids, sugars, or lipids reduced furan by 50-95%. These data suggest that more complex reaction systems result in much lower furan amounts as compared to the individual precursors, most likely due to competing reaction pathways.
[Mielke2010] "Quantitative determination of biogenic volatile organic compounds in the atmosphere using proton-transfer reaction linear ion trap mass spectrometry.",
, vol. 82, no. 19: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA., pp. 7952–7957, Oct, 2010.
Although oxidation of biogenic volatile organic compounds (BVOCs) plays an important role in tropospheric ozone and secondary organic aerosol production, significant uncertainties remain in our understanding of the impacts of BVOCs on ozone, aerosols, and climate. To quantify BVOCs, the proton-transfer reaction linear ion trap (PTR-LIT) mass spectrometer was previously developed. The PTR-LIT represents an improvement over more traditional techniques (including the proton-transfer reaction mass spectrometer), providing the capability to directly quantify and differentiate isomeric compounds by MS/MS analysis, with better time resolution and minimal sample handling, compared to gas chromatography techniques. Herein, we present results from the first field deployment of the PTR-LIT. During the Program for Research on Oxidants: Photochemistry, Emissions and Transport (PROPHET) summer 2008 study in northern Michigan, the PTR-LIT successfully quantified isoprene, total monoterpenes, and isomeric isoprene oxidation products methyl vinyl ketone and methacrolein at sub-parts per billion (nmol/mol) levels in a complex forest atmosphere. The utility of the fast time response of the PTR-LIT was shown by the measurement of rapid changes in isoprene, methyl vinyl ketone, and methacrolein, concurrent with changing ozone mole fractions. Overall, the PTR-LIT was shown to be a viable field instrument with the necessary sensitivity, selectivity, and time response to provide detailed measurements of BVOC mole fractions in complex atmospheric samples, at trace levels.
[Cappellin2012a] "On quantitative determination of volatile organic compound concentrations using proton transfer reaction time-of-flight mass spectrometry.",
Environ Sci Technol
, vol. 46, no. 4: IASMA Research and Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Area, Via E. Mach, 1, 38010, S. Michele a/A, Italy., pp. 2283–2290, Feb, 2012.
Proton transfer reaction - mass spectrometry (PTR-MS) has become a reference technique in environmental science allowing for VOC monitoring with low detection limits. The recent introduction of time-of-flight mass analyzer (PTR-ToF-MS) opens new horizons in terms of mass resolution, acquisition time, and mass range. A standard procedure to perform quantitative VOC measurements with PTR-ToF-MS is to calibrate the instrument using a standard gas. However, given the number of compounds that can be simultaneously monitored by PTR-ToF-MS, such a procedure could become impractical, especially when standards are not readily available. In the present work we show that, under particular conditions, VOC concentration determinations based only on theoretical predictions yield good accuracy. We investigate a range of humidity and operating conditions and show that theoretical VOC concentration estimations are accurate when the effect of water cluster ions is negligible. We also show that PTR-ToF-MS can successfully be used to estimate reaction rate coefficients between H(3)O(+) and VOC at PTR-MS working conditions and find good agreement with the corresponding nonthermal theoretical predictions. We provide a tabulation of theoretical rate coefficients for a number of relevant volatile organic compounds at various energetic conditions and test the approach in a laboratory study investigating the oxidation of alpha-pinene.
[Ruuskanen2009] "Quantitative long-term measurements of VOC concentrations by PTR-MS: annual cycle at a boreal forest site",
Atmospheric Chemistry and Physics Discussions
, vol. 9, no. 1: Copernicus GmbH, pp. 81–134, 2009.
 "Quantitative Validation of the n-Butanol Sniffin' Sticks Threshold Pens.",
, vol. 7, pp. 91–101, 2014.
<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' 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 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 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>