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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 16 Jun 2020

Submitted as: research article | 16 Jun 2020

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This preprint is currently under review for the journal AMT.

A portable, robust, stable and tunable calibration source for gas-phase nitrous acid (HONO)

Melodie Lao1, Leigh R. Crilley1, Leyla Salehpoor1, Teles C. Furlani1, Ilann Bourgeois2,3, J. Andrew Neuman2,3, Andrew W. Rollins2, Patrick R. Veres2, Rebecca A. Washenfelder2, Caroline C. Womack2,3, Cora J. Young1, and Trevor C. VandenBoer1 Melodie Lao et al.
  • 1Department of Chemistry, York University, Toronto, ON
  • 2NOAA Chemical Sciences Laboratory, Boulder, CO
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO

Abstract. Atmospheric HONO mixing ratios in indoor and outdoor environments span a range of less than a few parts per trillion by volume (pptv) up to tens of parts per billion by volume (ppbv) in combustion plumes. Previous HONO calibration sources have utilized proton transfer acid displacement from nitrite salts or solutions, with output that ranges from tens to thousands of ppbv. Instrument calibrations have thus required large dilution flows to obtain atmospherically relevant mixing ratios. Here we present a simple universal source to reach very low HONO calibration mixing ratios using a nitrite-coated reaction device with the addition of humid air and/or HCl from a permeation device. The calibration source developed in this work can generate HONO across the atmospherically relevant range and has high purity (90–99 %), reproducibility, and tunability. Mixing ratios at the tens of pptv level are easily reached with reasonable dilution flows. The calibration source can be assembled to start producing stable HONO mixing ratios (RSE ≤ 2 %) within two hours, with output concentrations varying ≤ 25 % following simulated transport or complete disassembly of the instrument, and ≤ 10 % under ideal conditions. The simplicity of this source makes it highly versatile for field and lab experiments. The platform facilitates a new level of accuracy in established instrumentation, as well as intercomparison studies to identify systematic HONO measurement bias and interferences.

Melodie Lao et al.

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Melodie Lao et al.

Melodie Lao et al.


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Latest update: 10 Jul 2020
Publications Copernicus
Short summary
Nitrous acid (HONO) is a key intermediate in the generation of oxidants and fate of nitrogen oxides in the atmosphere. High purity calibration sources that produce stable atmospherically relevant levels under field conditions have not been made to date, reducing measurement accuracy. In this study a simple salt-coated tube humidified with water vapour is demonstrated to produce pure stable low levels of HONO, with other approaches allowing the generation of higher amounts.
Nitrous acid (HONO) is a key intermediate in the generation of oxidants and fate of nitrogen...