Methods and Devices for the Preparation of Standard Gas Mixtures

Родинков

J of Separation Science

et al. 2021

Chromatomembrane process represents a universal approach to the separation of compounds in liquid-gas and liquid-liquid phases systems. However, the broad application of chromatomembrane separation methods in chemical analysis is restricted by the absence of serially produced chromatomembrane flow cells and the difficulties of their laboratory production. The present work addresses the preparation of chromatomembrane flow cell by using 3D printing. Fused deposition modeling and stereolithography were modes for the production of the flow cell using acrylonitrile-butadiene-styrene and polyacrylate-based Anycubic UV resins respectively. The separation and analytical performance of the 3D-printed flow cell were compared with a polyimide unit fabricated by a milling machine, the trial addressing the determination of phenol in the air. The method is based on chromatomembrane absorption of the analytes in 95 μL of the aqueous phase positioned in the cell. Reversed-phase HPLC with fluorimetric detection was applied for the determination of the absorbed analytes. The detection limit of phenols (phenol and m-cresol) in the air was 0.9 μg/m 3 by absorption preconcentration time of 10 min. The volumetric flow rate of the analyzed air through the chromatomembrane cell using an electrodriven aspirator was 0.1 L/min.

Section: Methodsmentioning

confidence: 99%

Chromatomembrane preconcentration of phenols using a new 3D printed microflow cell followed by reversed‐phase HPLC determination

Родинков

J of Separation Science

et al. 2021

“…The effects of the production and storage of ambient amount fraction N2O in synthetic air reference materials in cylinders on the reported amount fraction and delta value were compared to reported vales for dynamic reference materials produced from the same pure N2O source diluted with synthetic air (Figure 7). Dynamic reference materials demonstrate reduced adsorption effects compared to static standards particularly for low amount fraction reference materials (Platonov et al, 2018). Differences in reported delta value for static and dynamic standards of the same amount fraction would indicate fractionation events in either production method.…”

Section: Absence Of Fractionation Effects For Static Mixture Productionmentioning

confidence: 98%

Comment on amt-2021-45

Persijn¹

2021

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...

Chemie Ingenieur Technik

“…There are generally two major classes of techniques to generate standard gas mixtures under controlled conditions: static techniques and dynamic techniques , , . In static techniques various gases are dosed gravimetrically, monometrically and volumetrically, and added successively one component after another into close housings such as high‐pressurized gas cylinders with previous wall treatment . In dynamic mixing techniques, gases are mixed continuously on site from pure gases.…”

Section: Test Gas Generation Systemsmentioning

confidence: 99%

“…Dynamic gas mixing techniques are applied when there is a need to produce precise standard gas mixtures based on the desired process conditions and frequent adjustments of the composition of the gas mixture are required . Furthermore, dynamic methods inherently produce more homogeneous gas mixtures .…”

Section: Test Gas Generation Systemsmentioning

confidence: 99%

“…A detailed description of the advantages and disadvantages of the techniques shown in Fig. can be found in , , . From all possible dynamic methods the injection method, which can be carried out by injecting liquids (pure or multicomponent solutions) with syringes, motor‐driven syringes or syringe pumps into a diluting gas, offers several advantages.…”

Section: Test Gas Generation Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Design and Implementation of a Gas Generating System for Complex Gas Mixtures and Calibration Gases

Gómez

Takhtehfouladi

Schlögl

et al. 2020

A test gas generation system for complex gas mixtures designed to mimic real industrial gas matrices with traces raging from low pptv to high ppmv level and minor and main components ranging from low to high percentage levels with variable relative humidity levels (0–80 % RH) is presented. It combines different gas generation methods to study fragmentation patterns under controlled conditions by means of a proton transfer reaction time‐of‐flight mass spectrometer, the application of alternative feedstocks in catalytic processes as well as the performance of gas purification and conditioning processes.