Final report on EURAMET.QM-S8: Analysis of impurities in pure and balance gases used to prepare primary standard gas mixtures by the gravimetric method

Abstract

This supplementary comparison (EURAMET.QM-S8) concerns the purity analysis of nitrogen as used in reference gas mixture preparation. This project was carried out without adding impurities to the gas used for this comparison, and is therefore more representative to evaluate the analysis of carbon monoxide, carbon dioxide, methane, oxygen, argon and water impurities in high-purity nitrogen. The analysis of the amount-of-substance fraction water was optional.Two 50 litre high purity nitrogen cylinders were purchased from a well-qualified supplier of specialty gases. The listed components were expected to be present in the pure nitrogen at the target levels as a result of the purification of the nitrogen. From the start of this comparison it was clear that the comparison may not lead to reference values for the constituents analysed.The results indicate that analyses of high purity gases are often limited by the limits of detection of analytical equipment used. The reports of the participating laboratories also indicate that there is no agreed method of determination of the uncertainty on a detection limit value. The results provide useful information on the performance of participants. For all analysed components there is reasonable agreement in results for LNE, VSL, METAS and NPL. For BAM only the argon result is in agreement.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Purity Analysis of Gases Used in the Preparation of Reference Gas Standards Using a Versatile OPO-Based CRDS Spectrometer

“…Gas standards for nitrogen dioxide (NO 2 ) in cylinders typically contain also nitric acid (HNO 3 ) as was already shown by Fried and co-workers 30 years ago [21]. HNO 3 is formed in a reaction of NO 2 with residual water assumed to be mainly originating from the walls of the lling station or cylinder wall and in lesser extent from the matrix gas (high purity nitrogen from cylinders used for the mixture preparation can contain less than 20 nmol/mol water in the gas phase [22]). At VSL, a lot of e ort is put in reducing residual water during the preparation of NO 2 gas standards to suppress the formation of nitric acid [23].…”

Impurity Analysis of 5.5 N Nitrogen Gas and Its Impact on the Preparation of Class I Type Calibration Gas Mixtures

“…Very few laboratories reported the measurement of impurities in matrix gas for the preparation of calibration gas mixtures prepared by them. [6,7,32] Table 3 provides a summary of the literature survey conducted on the determination of impurities in ultra-high purity (UHP) nitrogen, along with the corresponding techniques employed. The results obtained in this paper are also compared with the reported findings, offering a comprehensive overview of the research in this area.…”

“…Many analytical techniques are available and used for trace level measurements e. g. electrochemical sensors, GC (gas chromatography) operated via different detectors like FID (Flame Ionization Detector), TCD (Thermal Conductivity Detector), PDHID (Pulse Discharge Helium Ionization Detector) and significant FTIR (Fourier Transform Infrared Spectroscopy). [7][8][9] Moreover, remarkable attention was gained by the wavelength-dependent absorption of analyte using optical spectroscopic methods like differential absorption lidar (DIAL), differential optical absorption spectroscopy (DOAS), and CRDS (cavity ring-down spectroscopy). [10,11] Functioning of CRDS is based upon regulating laser beam wavelength within IR range where the contaminant absorption peak occurs.…”

Dilution and permeation standards for the generation of NO, NO2and SO2calibration gas mixtures

“…For the analysis of O 2 , CO 2 and Ar ion-molecule reaction mass spectrometry (IMR MS) was used [39]. The validation of the measurement and calibration methods were described in [40,41]. CO 2 was measured since it is known to influence the transport properties of certain polymers [42].…”