Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO

Gingerysty, Nicholas J.; Odame-Ankrah, Charles A.; Jordan, Nick; Osthoff, Hans D.

Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO

dc.contributor.author	Gingerysty, Nicholas J.
dc.contributor.author	Odame-Ankrah, Charles A.
dc.contributor.author	Jordan, Nick
dc.contributor.author	Osthoff, Hans D.
dc.date.accessioned	2021-06-22T17:01:54Z
dc.date.available	2021-06-22T17:01:54Z
dc.date.issued	2020-12-07
dc.description.abstract	The reference method to quantify mixing ratios of the criteria air pollutant nitrogen dioxide (NO2) is NO-O3 chemiluminescence (CL), in which mixing ratios of nitric oxide (NO) are measured by sampling ambient air directly, and mixing ratios of NOx (= sum of NO and NO2) are measured by converting NO2 to NO using, for example, heated molybdenum catalyst or, more selectively, photolytic conversion (P-CL). In this work, the nitrous acid (HONO) interference in the measurement of NO2 by P-CL was investigated. Results with two photolytic NO2 converters are presented. The first used radiation centered at 395 nm, a wavelength region commonly utilized in P-CL. The second used light at 415 nm, where the overlap with the HONO absorption spectrum and hence its photolysis rate are less. Mixing ratios of NO2, NOx and HONO entering and exiting the converters were quantified by Thermal Dissociation Cavity Ring-down Spectroscopy (TD-CRDS). Both converters exhibited high NO2 conversion efficiency (CFNO2; >90%) and partial conversion of HONO. Plots of CF against flow rate were consistent with photolysis frequencies of 4.2 s 1 and 2.9 s 1 for NO2 and 0.25 s-1 and 0.10 s-1 for HONO at 395 nm and 415 nm, respectively. CFHONO was larger than predicted from the overlap of the emission and HONO absorption spectra. The results imply that measurements of NO2 by P-CL marginally but systematically overestimate true NO2 concentrations, and that this interference should be considered in environments with high HONO:NO2 ratios such as the marine boundary layer or in biomass burning plumes.	en_US
dc.description.grantingagency	Natural Sciences and Engineering Research Council (NSERC)	en_US
dc.identifier.citation	Gingerysty, N. J., Odame-Ankrah, C. A., Jordan, N., & Osthoff, H. D. (2021). Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO. Journal of Environmental Sciences, 107, 184–193. doi:10.1016/j.jes.2020.12.011	en_US
dc.identifier.doi	http://dx.doi.org/10.1016/j.jes.2020.12.011	en_US
dc.identifier.grantnumber	RGPIN/03849-2016	en_US
dc.identifier.uri	http://hdl.handle.net/1880/113522
dc.language.iso	eng	en_US
dc.publisher	Elsevier	en_US
dc.publisher.department	Chemistry	en_US
dc.publisher.faculty	Science	en_US
dc.publisher.hasversion	acceptedVersion	en_US
dc.publisher.institution	University of Calgary	en_US
dc.publisher.policy	https://www.elsevier.com/about/policies/sharing/policy-faq#	en_US
dc.rights	Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.subject	Photolytic conversion of NO2	en_US
dc.subject	HONO interference	en_US
dc.title	Interference from HONO in the measurement of ambient air NO2 via photolytic conversion and quantification of NO	en_US
dc.type	journal article	en_US
ucalgary.item.requestcopy	true	en_US
ucalgary.scholar.level	Faculty	en_US