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Scientific Articles - PTR-MS Bibliography

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Found 3 results
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Filters: Author is Viola, Roberto  [Clear All Filters]
[Soukoulis2013] Soukoulis, C., L. Cappellin, E. Aprea, F. Costa, R. Viola, TD.. Märk, F. Gasperi, and F. Biasioli, "PTR-ToF-MS, A Novel, Rapid, High Sensitivity and Non-Invasive Tool to Monitor Volatile Compound Release During Fruit Post-Harvest Storage: The Case Study of Apple Ripening", Food and Bioprocess Technology, vol. 6, no. 10: Springer US, pp. 2831-2843, 2013.
In the present study, the potential of PTR-ToF-MS for addressing fundamental and technical post-harvest issues was tested on the non-destructive and rapid monitoring of volatile compound evolution in three apple cultivars (‘Golden Delicious’, ‘Braeburn’ and ‘Gold Rush’) during 25 days of post-harvest shelf life ripening. There were more than 800 peaks in the PTR-ToF-MS spectra of apple headspace and many of them were associated with relevant compounds. Besides the ion produced upon proton transfer, we used the ion at mass 28.031 (C2H 4 +) produced by charge transfer from residual O 2 + as a monitor for ethylene concentration. ‘Golden Delicious’ apples were characterised by higher ethylene emission rates than ‘Gold Rush’ and ‘Braeburn’, and quantitative comparison has been supported by two segment piecewise linear model fitting. Ester evolution during post-harvest ripening is strongly dependent on endogenous ethylene concentration levels. For ‘Golden Delicious’ and ‘Braeburn’, sesquiterpenes (alpha-farnesene) exhibited a fast response to ethylene emission followed by a rapid decline after the endogenous ethylene maximum peak. Carbonyl compounds displayed a different time evolution as compared to esters and terpenes and did not show any evident relationship with ethylene. Methanol and ethanol concentrations during the entire storage period did not change significantly. We show how multivariate analysis can efficiently handle the large datasets produced by PTR-ToF-MS and that the outcomes obtained are in agreement with the literature. The different volatile compounds could be simultaneously monitored with high time resolution, providing advantages over the more established techniques for the investigation of VOC dynamics in fruit post-harvest storage trials.
[Schuhfried2012] Schuhfried, E., E. Aprea, L. Cappellin, C. Soukoulis, R. Viola, T. D. Maerk, F. Gasperi, and F. Biasioli, "Desorption kinetics with PTR-MS: Isothermal differential desorption kinetics from a heterogeneous inlet surface at ambient pressure and a new concept for compound identification", International journal of mass spectrometry, vol. -: Elsevier, pp. -, 2012.
Proton transfer reaction-mass spectrometry (PTR-MS) is a soft ionization mass spectrometric technique for monitoring volatile organic compounds (VOCs) with a very low limit of detection (LOD) (parts per trillion by volume) and excellent time resolution (split seconds). This makes PTR-MS a particularly interesting instrument for investigating surface desorption kinetics of volatile organic compounds (VOCs) under realistic conditions, i.e., at ambient pressure from a heterogeneous surface. Here, we report on the investigation of heterogeneous inlet surface kinetics with PTR-MS and based thereon, develop concepts to assist compound identification in PTR-MS. First, we studied differential isothermal desorption kinetics using heterogeneous inlet surface data measured by Mikoviny et al. [7] with their newly developed high-temp-PTR-MS. The best fit to their data is obtained with bimodal pseudo-first order kinetics. In addition, we explored the normalization of the data and calculated data points of the desorption isotherms. We found evidence that the interesting part of the isotherm can be linearized in a double log plot. Then we investigated the idea to use memory effects of the inlet system to assist compound identification. At the moment, the main problem is the dependence of the kinetics on the initial equilibrium gas phase adsorption concentration, and thus, the surface coverage. As a solution, we suggest an empirical, quasi-concentration independent, yet compound specific parameter: the normalized desorption time tnd describing the decline of the signal to 1/e2 of the initial concentration, normalized to an initial concentration of 10,000 counts per second (cps). Furthermore, we investigated property–property and structure–property relationships of this new parameter. Further possible improvements are discussed as well.
[Cappellin2012] Cappellin, L., C. Soukoulis, E. Aprea, P. Granitto, N. Dallabetta, F. Costa, R. Viola, T. D. Märk, F. Gasperi, and F. Biasioli, "PTR-ToF-MS and data mining methods: a new tool for fruit metabolomics", Metabolomics, vol. 8, no. 5: Springer, pp. 761–770, 2012.
Proton Transfer Reaction-Mass Spectrometry (PTR-MS) in its recently developed implementation based on a time-of-flight mass spectrometer (PTR-ToF-MS) has been evaluated as a possible tool for rapid non-destructive investigation of the volatile compounds present in the metabolome of apple cultivars and clones. Clone characterization is a cutting-edge problem in technical management and royalty application, not only for apple, aiming at unveiling real properties which differentiate the mutated individuals. We show that PTR-ToF-MS coupled with multivariate and data mining methods may successfully be employed to obtain accurate varietal and clonal apple fingerprint. In particular, we studied the VOC emission profile of five different clones belonging to three well known apple cultivars, such as ‘Fuji’, ‘Golden Delicious’ and ‘Gala’. In all three cases it was possible to set classification models which can distinguish all cultivars and some of the clones considered in this study. Furthermore, in the case of ‘Gala’ we also identified estragole and hexyl 2-methyl butanoate contributing to such clone characterization. Beside its applied relevance, no data on the volatile profiling of apple clones are available so far, our study indicates the general viability of a metabolomic approach for volatile compounds in fruit based on rapid PTR-ToF-MS fingerprinting.

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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).

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.

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.


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


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