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International Comparison CCQM-K41: Hydrogen Sulfide in Nitrogen

Published

Author(s)

Franklin R. Guenther, Walter R. Miller Jr.

Abstract

This key comparison was intended to compare the capabilities for the preparation and value assignment of gas standards for hydrogen sulfide in nitrogen, maintained at the participating national metrology institutes. The range of the nominal amount-of-substance fractions of the comparison standard is 10 ?mol/mol, which is close to regulatory levels in most countries.The measurements in this key comparison took place in 2005. There were 7 participants. The Key Comparison Reference Value (KCRV) was calculated from the participant s data, and thus represents a consensus value. This was necessary due to the fact that the cylinders could not be prepared gravimetrically as hydrogen sulfide may be absorbed onto the walls of the cylinder, and has been shown to be unstable in cylinders at the comparison concentration. Thus the gas mixtures were procured from a vendor as a homogeneous lot of 12 cylinders, analyzed by the coordinating laboratory for 6 months to determine stability, and then those determined to be stable were shipped to the participants for analysis. After analysis, the cylinders were returned to the coordinating laboratory for reanalysis. Through this protocol the coordinating laboratory could track stability. In parallel, the coordinating laboratory also analyzed a stable reference, a hydrogen sulfide gas mixture that had been shown to be stable over many years. Using the lot stability data, the participant s analytical results, and the coordinating laboratories analysis of the stable reference, a consensus value could be calculated which represent the concentration of the stable reference.The key comparison demonstrated that the results of the laboratories agreed within 0.5 % relative to the consensus value. A subset of 6 participants results agreed with the consensus value to better than 0.25 %.
Citation
Metrologia

Keywords

hydrogen sulfide, key comparison

Citation

Guenther, F. and Miller Jr., W. (2008), International Comparison CCQM-K41: Hydrogen Sulfide in Nitrogen, Metrologia (Accessed April 19, 2024)
Created October 16, 2008