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

Lao, Melodie; Crilley, Leigh R.; Salehpoor, Leyla; Furlani, Teles C.; Bourgeois, Ilann; Neuman, J. Andrew; Rollins, A. W.; Veres, P. R.; Washenfelder, R. A.; Womack, Caroline C.; Young, Cora J.; VandenBoer, Trevor C.

doi:10.5194/amt-13-5873-2020

Cited by 21 publications

(26 citation statements)

References 76 publications

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“…This interference will be examined in more detail in a future publication. It appears unlikely that outdoor mixing ratios of HOCl would be a significant interference given that HOCl mixing ratios in marine environments are generally less than 1 ppb (Lawler et al, 2011), much lower than the level of indoor HOCl that produced an interference during HOMEChem. While the absorption cross sections of HOBr and HOI are factors of approximately 10 and 30 times greater than that of HOCl at 355 nm (Burkholder et al, 2019), outdoor ambient mixing ratios of HOBr and HOI are much lower than ambient HOCl, with measured values of HOBr less than 26 ppt in the arctic marine boundary layer (Liao et al, 2012) and measured mixing ratios of HOI less than 70 ppt in the marine boundary layer (Tham et al, 2021).…”

Section: Potential Interferencesmentioning

confidence: 99%

Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

et al. 2021

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Abstract. A new instrument for the measurement of atmospheric nitrous acid (HONO) and hydroxyl radicals (OH) has been developed using laser photofragmentation (LP) of HONO at 355 nm after expansion into a low-pressure cell, followed by resonant laser-induced fluorescence (LIF) of the resulting OH radical fragment at 308 nm similar to the fluorescence assay by gas expansion technique (FAGE). The LP/LIF instrument is calibrated by determining the photofragmentation efficiency of HONO and calibrating the instrument sensitivity for detection of the OH fragment. In this method, a known concentration of OH from the photo-dissociation of water vapor is titrated with nitric oxide to produce a known concentration of HONO. Measurement of the concentration of the OH radical fragment relative to the concentration of HONO provides a measurement of the photofragmentation efficiency. The LP/LIF instrument has demonstrated a 1σ detection limit for HONO of 9 ppt for a 10 min integration time. Ambient measurements of HONO and OH from a forested environment and an urban setting are presented along with indoor measurements to demonstrate the performance of the instrument.

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Section: Potential Interferencesmentioning

confidence: 99%

Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

et al. 2021

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“…The accuracy/uncertainty is the hardest to compare due to the differences in assessment. A particular challenge is that other methods require external calibrations to determine accuracy and a stable, accurately calibrated HCl source at atmospherically relevant mixing ratios is challenging to obtain (Lao et al, 2020;MacInnis et al, 2016). In contrast, spectroscopic techniques offer a distinct advantage as they are absolute measurements and accuracy determinations rely on propagating uncertainty in the measured parameters (i.e.…”

Section: Instrument Performancementioning

confidence: 99%

Validation of a new cavity ring-down spectrometer for measuring tropospheric gaseous hydrogen chloride

Furlani¹,

Veres²,

Dawe³

et al. 2021

Preprint

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Abstract. Reliable, sensitive, and widely available hydrogen chloride (HCl) measurements are important for understanding oxidation in many regions of the troposphere. We configured a commercial HCl cavity ring-down spectrometer (CRDS) for sampling HCl in the ambient atmosphere and developed calibration and validation techniques to characterize the measurement uncertainties. The CRDS makes fast, sensitive, and robust measurements of HCl in a high finesse optical cavity coupled to a laser centered at 5739 cm−1. The accuracy was determined to reside between 5–10 %, calculated from laboratory calibrations and an ambient air intercomparison with annular denuders. The precision and limit of detection (3σ) in the 0.5 Hz measurement were below 6 pptv and 18 pptv, respectively for a 30 second integration interval in zero air. The response time of this method is primarily characterized by fitting decay curves to a double exponential equation and is impacted by inlet adsorption/desorption, with these surface effects increasing with RH and decreasing with decreasing HCl mixing ratios. The response time for the tested inlet was 2–6 minutes under the most and least optimal conditions, respectively. An intercomparison with the EPA compendium method for quantification of acidic atmospheric gases showed good agreement, yielding a linear relationship statistically equivalent to unity (slope of 0.97 ± 0.15). The CRDS from this study can detect HCl at atmospherically relevant mixing ratios, often performing comparable or better in sensitivity, selectivity, and response-time from previously reported HCl detection methods.

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“…The advantage of using H2SO4 is the missing formation of unwanted byproducts like HCl and ClNO as observed in HONO sources using the volatile HCl, which are based on the original concept of Febo et al (1995). While these sources can be carefully optimized for low by-product formation (Febo et al, 1995;Gingerysty and Oshoff, 2020;Lao et al, 2020), the use of the non-volatile H2SO4 completely excludes the still existing risk of any 275 malfunction of the source. For example, when the Febo et al source was used in our laboratory two decades ago (Brust et al, 2000), we often had problems related with the homogeneous mixing of the solid NaNO2 and with the use of low relative humidity, leading to lower purity of HONO.…”

Section: General Considerations 270mentioning

confidence: 99%

“…In most recent studies, the acid displacement using HCl was applied (Ren et al, 2010;Reed et al, 2016;Gingerysty and Osthoff, 2020;Lao et al, 2020), which are all based on the pioneering study of Febo et al (1995). Gaseous HCl is produced by any kind of permeation source and after humidification reacts heterogeneously with solid sodium nitrite.…”

Section: Introductionmentioning

confidence: 99%

“…Caused by the increasing general interest in the chemistry of HONO and in the development of 75 simple HONO sources during the last years (e.g. Gingerysty and Osthoff, 2020;Lao et al, 2020), the aim of the present study was the characterization of the source in more detail and also to apply Henry's law for its theoretical quantification to be used for the stand-alone calibration of HONO instruments.…”

Section: Introductionmentioning

confidence: 99%

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A Source for the Continuous Generation of Pure and Quantifiable HONO Mixtures

Villena

Kleffmann

2021

Preprint

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Abstract. A continuous source for the generation of pure HONO mixtures was developed and characterized, which is based on the Henry’s law solubility of HONO in acidic aqueous solutions. With the help of a peristaltic pump diluted nitrite and sulfuric acid solutions are mixed in a temperature-controlled stripping coil, which is operated with pure nitrogen or synthetic air at gas flow rates of 0.5–2 L min-1. Caused by the acidic conditions of the aqueous phase (pH ≈ 2.5), nitrite is almost completely converted into HONO, which partitions to the gas phase limited by its known solubility in water. The source shows a fast time response of ~2 min (0–90 %) at higher concentrations and an excellent long-time stability (2&sigma; noise <1 %). The HONO emission of the source perfectly correlates with the nitrite concentration from the sub-ppb range up to 500 ppb. The rate of NOx formation increases quadratically with the HONO concentration from non-detectable values at atmospheric relevant HONO concentrations reaching a NOx content of 1.6 % at 500 ppb. A general equation based on Henry’s law is developed, whereby the HONO concentration of the source can be calculated using measured experimental parameters, i.e. nitrite concentration, liquid flow rates, gas flow rate, pH of the solution and temperature of the stripping coil. In the equation, the known Henry’s law constant of HONO in sulfuric acid solutions is used. For the calculation of the effective Henry’s law constant, the acid dissociation equilibrium of HONO/nitrite is used as a variable to adjust the theoretical HONO concentration to the measured values. From the average of all experimental data the equilibrium of HONO/nitrite is well described by pKa = 1021.53/T – 0.449. The pKa of 3.0±0.1 (1&sigma;) at 25 °C is in good agreement with the range of 2.8–3.28 published in former studies. A standard deviation between all measured and theoretical HONO concentrations of only ±3.8 % was observed and a conservative upper limit accuracy of the HONO concentration of better 10 % is estimated. Thus, for the first time, a stable HONO source is developed, which can be used for the absolute calibration of HONO instruments.

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

Cited by 21 publications

References 76 publications

Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

Development of a laser-photofragmentation laser-induced fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

Validation of a new cavity ring-down spectrometer for measuring tropospheric gaseous hydrogen chloride

A Source for the Continuous Generation of Pure and Quantifiable HONO Mixtures

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