Galloway, M. M. and Chhabra, P. S. and Chan, A. W. H. and Surratt, J. D. and Flagan, R. C. and Seinfeld, J. H. and Keutsch, F. N. (2009) Glyoxal uptake on ammonium sulphate seed aerosol: reaction products and reversibility of uptake under dark and irradiated conditions. Atmospheric Chemistry and Physics, 9 (10). pp. 3331-3345. ISSN 1680-7316. http://resolver.caltech.edu/CaltechAUTHORS:20090820-133254405
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Chamber studies of glyoxal uptake onto ammonium sulphate aerosol were performed under dark and irradiated conditions to gain further insight into processes controlling glyoxal uptake onto ambient aerosol. Organic fragments from glyoxal dimers and trimers were observed within the aerosol under dark and irradiated conditions. Glyoxal monomers and oligomers were the dominant organic compounds formed under the conditions of this study; glyoxal oligomer formation and overall organic growth were found to be reversible under dark conditions. Analysis of high-resolution time-of-flight aerosol mass spectra provides evidence for irreversible formation of carbon-nitrogen (C-N) compounds in the aerosol. We have identified 1H-imidazole-2-carboxaldehyde as one C-N product. To the authors' knowledge, this is the first time C-N compounds resulting from condensed phase reactions with ammonium sulphate seed have been detected in aerosol. Organosulphates were not detected under dark conditions. However, active photochemistry was found to occur within aerosol during irradiated experiments. Carboxylic acids and organic esters were identified within the aerosol. An organosulphate, which had been previously assigned as glyoxal sulphate in ambient samples and chamber studies of isoprene oxidation, was observed only in the irradiated experiments. Comparison with a laboratory synthesized standard and chemical considerations strongly suggest that this organosulphate is glycolic acid sulphate, an isomer of the previously proposed glyoxal sulphate. Our study shows that reversibility of glyoxal uptake should be taken into account in SOA models and also demonstrates the need for further investigation of C-N compound formation and photochemical processes, in particular organosulphate formation.
|Additional Information:||© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 7 October 2008 – Published in Atmos. Chem. Phys. Discuss.: 12 December 2008. Revised: 14 May 2009 – Accepted: 19 May 2009 – Published: 25 May 2009. The authors are grateful to Tehshik Yoon for his helpful discussions about organic synthesis. This work was supported by the Camille and Henry Dreyfus Foundation, the NDSEG-ARO, the US Department of Energy grant DE-FG02- 05ER63 983 and US Environmental Protection Agency STAR grant RD-83 374 901. It has not been formally reviewed by EPA. The views expressed in this document are solely those of the authors and the EPA does not endorse any products in this publication. Development of the Madison-LIP instrument was supported by the National Science Foundation, Division of Atmospheric Sciences, Atmospheric Chemistry Program (grant 0 724 912), and the NDSEG-ARO. The Waters UPLC-LCT Premier XT time-of-flight mass spectrometer was purchased in 2006 with a grant from the National Science Foundation, Chemistry Research Instrumentation and Facilities Program (CHE-0 541 745).|
|Official Citation:||Galloway, M. M., Chhabra, P. S., Chan, A. W. H., Surratt, J. D., Flagan, R. C., Seinfeld, J. H., and Keutsch, F. N.: Glyoxal uptake on ammonium sulphate seed aerosol: reaction products and reversibility of uptake under dark and irradiated conditions, Atmos. Chem. Phys., 9, 3331-3345, 2009. www.atmos-chem-phys.net/9/3331/2009/|
|Usage Policy:||This work is distributed under the Creative Commons Attribution 3.0 License.|
|Deposited By:||George Porter|
|Deposited On:||04 Sep 2009 18:35|
|Last Modified:||26 Dec 2012 11:13|
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