Synthetic Zero Air Reference Material for High Accuracy Greenhouse Gas Measurements

Pearce, Ruth; Resner, Kate; Worton, David R.; Brewer, Paul J.

doi:10.1021/acs.analchem.8b04297

Cited by 4 publications

(7 citation statements)

References 14 publications

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“…Two approaches were used to quantify the amount fraction of nitrous oxide in the matrix gas. The first involved a standard addition method. ,, A high-accuracy dilution device, developed at the NPL, referred to as the adjustable gas standard (AGS), was used to spike the matrix gas under test with known amounts of nitrous oxide. The AGS produced seven mixtures with dilution ratios between nominal values of 1:350 and 1:2000.…”

Section: Methodsmentioning

confidence: 99%

Step Change in Improving the Accuracy of Nitrous Oxide Reference Materials for Underpinning Atmospheric Composition Measurements

et al. 2023

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We have employed a new approach to quantify the amount fraction of nitrous oxide in a synthetic air matrix gas used to prepare high-accuracy reference materials of the same component. Until now, this was the largest contributor to the measurement uncertainty of nitrous oxide in air reference materials at atmospheric amount fractions (∼330 nmol mol–1), as identified in a recent international comparison. A novel preconcentration method has resulted in a measurement of 363 pmol mol–1 of nitrous oxide in a synthetic air matrix gas with an expanded uncertainty of 27 pmol mol–1. This represents a significant breakthrough as using these developments with an optimized dilution hierarchy (to minimize the gravimetric uncertainty) promises to result in SI traceable reference materials with expanded uncertainties as low as 0.032% relative (k = 2). This supports the World Meteorological Organization–Global Atmosphere Watch network compatibility goal for underpinning atmospheric observations.

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Section: Methodsmentioning

confidence: 99%

Step Change in Improving the Accuracy of Nitrous Oxide Reference Materials for Underpinning Atmospheric Composition Measurements

et al. 2023

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“…The data demonstrates that the internal passivation process causes negligible changes to the 355 N2O analyser response for amount fraction with changes in cylinder pressure. The water vapour content of similar mixtures in synthetic air was measured to be around 0.5 µmol mol -1 (Hill-Pearce et al, 2018).…”

Section: Cylinder Treatments For Enhanced Stability With Pressurementioning

confidence: 98%

“…The characterisation of the CRDS for reported delta values with N2O amount fraction was assessed with both statically and dynamically generated reference materials. Dynamic reference materials were produced in the amount fraction range 150-1100 nmol mol -1 by dilution from a nominally 320 µmol mol -1 N2O in synthetic air reference material with synthetic air using a dynamic dilution device comprising one diluent and three standard critical flow orifices (Hill-Pearce et al, 2018 and dynamic reference materials were generated alternately for 4 iterations, with synthetic air measured between each set. Due to the large number of measurements recorded, a reduced sampling time of 5 minutes was adopted for each measurement interval resulting in a slightly lower standard deviation of 0.03 nmol mol -1 for amount fractions.…”

Section: Characterisation Of the Crds For Reported Delta Values With mentioning

confidence: 99%

“…The amount fraction of N2O in the matrix was determined by standard addition of a 325 nmol mol -1 reference material into a synthetic air prepared with the same argon in nitrogen premix and the same oxygen and nitrogen cylinders. This method is as described in (Hill-Pearce et al, 2018). The zero offset of the analyser was determined by removal of trace N2O in the matrix gas (SAES Getter/Entegris PS15 GC-50).…”

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Comment on amt-2021-45

Persijn¹

2021

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The precise measurement of the amount fraction of atmospheric nitrous oxide (N2O) is required to understand global emission trends. Analysis of the site-specific stable isotopic composition of N2O provides a means to differentiate emission sources. The availability of accurate reference materials of known N2O amount fractions and isotopic composition is critical for achieving these goals. We present the development of nitrous oxide gas reference materials for underpinning measurements of atmospheric composition and isotope ratio. Uncertainties target the World Metrological Organisation Global Atmosphere Watch (WMO-GAW) compatibility goal of 0.1 nmol mol -1 and extended compatibility goal of 0.3 nmol mol -1 , for atmospheric N2O measurements in an amount fraction range of 325-335 nmol mol -1 . We also demonstrate the stability of amount fraction and isotope ratio of these reference materials and present a characterisation study of the cavity ring down spectrometer used for analysis of the reference materials.Crucial for the development of reference materials is the stability of the N2O composition and isotope ratio. (Ganesan et al., 2013) reported no significant drift in amount fraction for a nominally 325 nmol mol -1 N2O in compressed air reference material in an aluminium cylinder (Scott Marrin) over a three-year period. Similar findings were reported by (Lushozi et al., 2019) but no study is available yet on the stability of the N2O isotope ratio at ambient amount fractions. In addition, improvements in the preparation and availability of N2O reference materials at ambient amount fraction is required to achieve the challenging WMO-GAW compatibility goals (Brewer et al., 2019).We present work on the development of N2O reference materials for underpinning atmospheric composition and isotope ratio with uncertainties targeting the WMO-GAW compatibility goals. We describe the characterisation of precision, repeatability and drift of a CRDS laser spectrometer. We also present work on all elements of the preparation process such as gravimetry, purity analysis, validation, stability, passivation of storage media, and matrix effects. These developments are extended to multi-components mixtures of N2O with other greenhouse gases (CO2, CH4 and CO) in a synthetic air matrix containing atmospheric amount fractions of argon, oxygen and nitrogen, as required for calibration of spectroscopic instruments for atmospheric measurements. Experimental Gravimetric preparation of primary reference materials (PRMs)All Primary Reference Materials (PRMs) were prepared by gravimetry, in accordance with ISO 6142-1:2015, in 10 L aluminium cylinders (Luxfer) with a range of outlet diaphragm valves (Ceodeux): BS341 no. 14, DIN 477 no. 1 and DIN 447 no. 8. The cylinders were treated internally by electropolishing (Luxfer) or with a range of proprietary passivation processes including SpectraSeal™ (BOC), Megalong™ and Aculife IV/ III™ (Air Liquide) to inhibit adsorption of target components.Cylinders were evacuated using an oil-free pump (Scrol...

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Section: Characterisation Of the Crds For Reported Delta Values With mentioning

confidence: 99%

Gas Reference Materials for Underpinning Atmospheric Measurements of Stable Isotopes of Nitrous Oxide

Pearce¹,

Hillier²,

Webber³

et al. 2021

Preprint

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Abstract. The precise measurement of the amount fraction of atmospheric nitrous oxide (N2O) is required to understand global emission trends. Analysis of the site-specific stable isotopic composition of N2O provides a means to differentiate emission sources. The availability of accurate reference materials of known N2O amount fractions and isotopic composition is critical for achieving these goals. We present the development of nitrous oxide gas reference materials for underpinning measurements of atmospheric composition and isotope ratio. Uncertainties target the World Metrological Organisation Global Atmosphere Watch (WMO-GAW) compatibility goal of 0.1 nmol mol−1 and extended compatibility goal of 0.3 nmol mol−1, for atmospheric N2O measurements in an amount fraction range of 325–335 nmol mol−1. We also demonstrate the stability of amount fraction and isotope ratio of these reference materials and present a characterisation study of the cavity ring down spectrometer used for analysis of the reference materials.

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Synthetic Zero Air Reference Material for High Accuracy Greenhouse Gas Measurements

Cited by 4 publications

References 14 publications

Step Change in Improving the Accuracy of Nitrous Oxide Reference Materials for Underpinning Atmospheric Composition Measurements

Step Change in Improving the Accuracy of Nitrous Oxide Reference Materials for Underpinning Atmospheric Composition Measurements

Comment on amt-2021-45

Gas Reference Materials for Underpinning Atmospheric Measurements of Stable Isotopes of Nitrous Oxide

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