Stability of gaseous volatile organic compounds contained in gas cylinders with different internal wall treatments

Rhoderick, George C.; Cecelski, Christina E.; Miller, Walter R.; Worton, David R.; Moreno, Sergi; Brewer, Paul J.; Viallon, Joële; Idrees, Faraz; Moussay, Philippe; Kim, Yong Doo; Kim, Dalho; S, Lee; Baldan, Annarita; Lǐ, Jiànróng

doi:10.1525/elementa.366

Cited by 13 publications

(17 citation statements)

References 28 publications

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“…The PID response to isoprene is calibrated using a primary gas standard supplied by the National Physical Laboratory (NPL), certified as containing 5.01 ± 0.25 nmol mol −1 (or ppb) isoprene in a nitrogen matrix (uncertainty provided at the k = 2 level). The gas mixture is stored in a 10 L Experis cylinder (Air Products); this type of cylinder has been demonstrated to provide maximum stability (up to 2 years) for VOC mixtures over time (Allen et al, 2018;Rhoderick et al, 2019). The primary standard is only used for calibration in the laboratory; for field deployments, a smaller secondary gas standard is used instead.…”

Section: Calibration Of Output Chromatogramsmentioning

confidence: 99%

“…This secondary gas standard is prepared in a 500 mL SilcoNert-treated stainless steel cylinder (Sulfinert sample cylinder, TPED, 1/4 , Thames Restek). This type of treated cylinder exhibits very good long-term stability for a number of VOCs (Allen et al, 2018;Rhoderick et al, 2019). The exact isoprene amount fraction in the secondary standard is determined by validating it against the NPL primary standard.…”

Section: Calibration Of Output Chromatogramsmentioning

confidence: 99%

“…An alternative method to detect environmental VOCs is with grab samples (Robinson et al, 2005). These can either be whole air samples or adsorbent tubes, where air samples (or some specific air components) are collected in an inert vessel and analysed at a later date.…”

Section: Introductionmentioning

confidence: 99%

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iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs

et al. 2020

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Abstract. The iDirac is a new instrument to measure selected hydrocarbons in the remote atmosphere. A robust design is central to its specifications, with portability, power efficiency, low gas consumption and autonomy as the other driving factors in the instrument development. The iDirac is a dual-column isothermal oven gas chromatograph with photoionisation detection (GC-PID). The instrument is designed and built in-house. It features a modular design, with the novel use of open-source technology for accurate instrument control. Currently configured to measure biogenic isoprene, the system is suitable for a range of compounds. For isoprene measurements in the field, the instrument precision (relative standard deviation) is ±10 %, with a limit of detection down to 38 pmol mol−1 (or ppt). The instrument was first tested in the field in 2015 during a ground-based campaign, and has since shown itself suitable for deployment in a variety of environments and platforms. This paper describes the instrument design, operation and performance based on laboratory tests in a controlled environment as well as during deployments in forests in Malaysian Borneo and central England.

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Section: Calibration Of Output Chromatogramsmentioning

confidence: 99%

Section: Calibration Of Output Chromatogramsmentioning

confidence: 99%

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iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs

et al. 2020

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“…VOCs monitoring, regardless of the application, requires the use of pipes, fittings, liners, cylinders, joints, pressure regulators, environmental chambers, generation devices, and measurement instruments, all built using solid materials of different nature. In all these applications, the gas-wall interactions affect the mole fraction of VOCs [18][19][20][21][22][23][24][25][26]. Sampling pipes that convey the air from the atmosphere to the detectors can potentially disturb the measurement of the amount of the analyte segregating on or releasing from the wall surfaces, i.e., these interactions challenge the accuracy of the measurement [26].…”

Section: Introductionmentioning

confidence: 99%

“…Where reaction products are formed by gas to wall interactions, identification of substances can be difficult [36]. Interactions can affect the stability and accuracy of the standard gas mixture at trace level for both static and dynamic preparations [5,18,19,31,[37][38][39]. The losses due to interactions in cylinders had been widely investigated in References [40][41][42][43][44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Reproducibility of the Quantification of Reversible Wall Interactions in VOC Sampling Lines

2021

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Volatile Organic Compounds (VOCs) are widely measured at ppb and ppt level in many contexts, from therapeutic drug control in respiratory diseases to monitoring of climate change and indoor air quality. The need for accuracy is a common denominator in all these fields. The interactions between gas mixtures and solid surfaces in sampling lines and instruments play an important role in calculating the total uncertainty of the amount of VOC. The amount of substances in the gas mixture is affected by its reversible and irreversible interactions with the sampling line. The main aim of this paper is to propose and discuss a method to quantify the amount of substance segregated by reversible interactions on sampling lines. To validate the proposed method, the areic amount of a VOC (Acetone) is measured for a commercial test pipe (Sulfinert®) as the amount of substance per unit area of the internal surface of the test pipe segregated from the flowing gas mixture. Stainless steel coated by Sulfinert® was chosen as a test material because of its wide use and its limited irreversible and permeation effects. A certified gas mixture of Acetone in air with a nominal mole fraction of 10 µmol mol−1 was used for validation. Broad temperature control was used and the sensibility of the method to the temperature and the pressure has been evaluated to correct the bias due to physical condition. The sensitivity to the residence time and the Reynolds number of the gas flow has been evaluated to verify the reaching of equilibrium and the limits of the applicability of the method. The areic amount of Acetone at equilibrium on Sulfinert® coated pipe was measured as 40 nmol m−2, and an equilibrium constant value of around 0.2 m was calculated as the ratio between the superficial amount segregated on the wall and the amount concentration of Acetone in the mixture, both at the equilibrium. The observed reproducibility was better than 2.5%. This method is aimed to investigate VOC losses due to interactions for many VOC/material systems at a lower amount of substance levels.

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Bilateral comparison of primary reference materials (PRMs) containing methanol, ethanol and acetone in nitrogen

et al. 2022

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A range of oxygenated volatile organic compounds (OVOCs) are present in the atmosphere as a result of direct emissions and as products of atmospheric oxidation. Long-term measurements are important to understand changes to these emission sources and atmospheric oxidation processes. Accurate and stable traceable gaseous primary reference materials are needed to underpin rigorous quality assurance and quality control at monitoring stations such as those organised by the World Meteorological Organization Global Atmosphere Watch (WMO-GAW) programme. The development of a capability for providing traceable primary reference materials (PRMs) of OVOCs is of paramount importance due to the increasing prevalence of these compounds in the urban atmosphere and also because there is currently no Central Calibration Laboratory (CCL) for these components within the WMO-GAW programme. This EURAMET bilateral comparison demonstrates the measurement compatibility (≤ 3%) for three OVOCs (methanol, ethanol and acetone) at nominally 5 µmol mol−1 between two National Metrology Institutes: the National Physical Laboratory (NPL), UK and the Van Swinden Laboratorium (VSL), the Netherlands. The comparison shows that a gravimetric method for value assignment is applicable to acetone but that a more complicated procedure must be employed to value assign methanol and ethanol due to corrections for adsorption effects, which can be as large as 10 % of the nominal value. This work demonstrates the importance of making appropriate corrections to ensure the accuracy of these reference materials. NPL and VSL used different approaches to make these corrections providing confidence and independent verification. This work supports new calibration and measurement capabilities for methanol, ethanol and acetone in the range of 1 μmol mol−1 –10 μmol mol−1 with expanded uncertainties of 6.9 % (3 %), 7.3 % (3 %) and 1.7 % (2 %) for NPL (VSL), respectively, to be realized in the key comparison database and supports the development of the required traceability infrastructure to underpin long-term global measurements of these OVOCs.

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Stability of gaseous volatile organic compounds contained in gas cylinders with different internal wall treatments

Cited by 13 publications

References 28 publications

iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs

iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs

Reproducibility of the Quantification of Reversible Wall Interactions in VOC Sampling Lines

Bilateral comparison of primary reference materials (PRMs) containing methanol, ethanol and acetone in nitrogen

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