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Scientific Articles - PTR-MS Bibliography

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Found 2 results
Title [ Year(Asc)]
Filters: Author is Abbatt, Jonathan P D.  [Clear All Filters]
[1607] Borduas, N., G. { da Silva}, J. G. Murphy, and J. P. D. Abbatt, "Experimental and Theoretical Understanding of the Gas Phase Oxidation of Atmospheric Amides with OH Radicals: Kinetics, Products, and Mechanisms.", J Phys Chem A, Jul, 2014.
<p>Atmospheric amides have primary and secondary sources and are present in ambient air at low pptv levels. To better assess the fate of amides in the atmosphere, the room temperature (298 &plusmn; 3 K) rate coefficients of five different amides with OH radicals were determined in a 1 m(3) smog chamber using online proton-transfer-reaction mass spectrometry (PTR-MS). Formamide, the simplest amide, has a rate coefficient of (4.44 &plusmn; 0.46) &times; 10(-12) cm(3) molec(-1) s(-1) against OH, translating to an atmospheric lifetime of &sim;1 day. N-methylformamide, N-methylacetamide and propanamide, alkyl versions of formamide, have rate coefficients of (10.1 &plusmn; 0.6) &times; 10(-12), (5.42 &plusmn; 0.19) &times; 10(-12), and (1.78 &plusmn; 0.43) &times; 10(-12) cm(3) molec(-1) s(-1), respectively. Acetamide was also investigated, but due to its slow oxidation kinetics, we report a range of (0.4-1.1) &times; 10(-12) cm(3) molec(-1) s(-1) for its rate coefficient with OH radicals. Oxidation products were monitored and quantified and their time traces were fitted using a simple kinetic box model. To further probe the mechanism, ab initio calculations are used to identify the initial radical products of the amide reactions with OH. Our results indicate that N-H abstractions are negligible in all cases, in contrast to what is predicted by structure-activity relationships. Instead, the reactions proceed via C-H abstraction from alkyl groups and from formyl C(O)-H bonds when available. The latter process leads to radicals that can readily react with O2 to form isocyanates, explaining the detection of toxic compounds such as isocyanic acid (HNCO) and methyl isocyanate (CH3NCO). These contaminants of significant interest are primary oxidation products in the photochemical oxidation of formamide and N-methylformamide, respectively.</p>
[Vlasenko2008] Vlasenko, A., I. J. George, and J. P. D. Abbatt, "Formation of volatile organic compounds in the heterogeneous oxidation of condensed-phase organic films by gas-phase OH.", J Phys Chem A, vol. 112, no. 7: Department of Chemistry and Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada., pp. 1552–1560, Feb, 2008.
The yield of volatile organic compounds (VOCs) from the heterogeneous oxidation of condensed-phase organic and hydrocarbon soot films by gas-phase OH has been studied in a coated-wall flow tube at room temperature. Simultaneously, OH concentrations are measured using a chemical-ionization mass spectrometer (CIMS) operated in negative ion mode and VOCs are measured using a commercial proton-transfer-reaction mass spectrometer (PTR-MS). It is observed that a variety of aldehydes/carbonyls and carboxylic acids are formed. Specifically, detailed experiments were conducted with stearic acid, where products are observed that contain as many as 13 carbon atoms with the average carbon number of the products between 3 and 5. The yield of VOCs, relative to the loss of OH radicals, is strongly dependent on the partial pressure of O2 in the carrier gas, ranging from 0.08 +/- 0.03 in a nominally pure He carrier gas to 0.34 +/- 0.14 in 6 Torr of pure O2. Yields from other organics are somewhat lower than those from stearic acid, ranging in conditions of pure O2 from 0.10 +/- 0.04 for BES (bis(ethylhexyl)sebacate), to 0.03 +/- 0.01 for n-hexane soot, to 0.01 +/- 0.005 for pyrene. Under atmospheric conditions, OH oxidation of select organics may be an efficient source of small VOCs. In particular, formic acid is formed in significant yield from all the surfaces.

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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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