| 1. |
- Arrhenius, Karine, et al.
(författare)
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Traceable reference gas mixtures for sulfur-free natural gas odorants
- 2014
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 13:1, s. 6695-6702
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Tidskriftsartikel (refereegranskat)abstract
- The first reference gas mixtures of sulfur-free natural gas odorants that are traceable to the International System of Units (SI) have been produced and their compositions validated. These mixtures, which contain methyl acrylate and ethyl acrylate at amount fractions between 1.1 and 2.1 μmol mol-1, can be used to underpin measurements of sulfur-free odorants, which are increasingly being used to odorize natural gas in transmission networks as they have less harmful properties than traditional sulfur-containing odorants. The reference gas mixtures produced have been shown to be stable in passivated aluminum cylinders for at least 8 months and have been validated (to within 6% or less) by interlaboratory measurements at three National Measurement Institutes. The stability of methyl acrylate and ethyl acrylate in gas sampling bags has been investigated, and the challenges of analyzing 2-ethyl-3- methylpyrazine, which is used as a stabilizer in sulfur-free odorants, are also briefly discussed.
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| 2. |
- Brown, Andrew S., et al.
(författare)
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Sampling of gaseous sulfur-containing compounds at low concentrations with a review of best-practice methods for biogas and natural gas applications
- 2015
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Ingår i: TrAC. Trends in analytical chemistry. - : Elsevier BV. - 0165-9936 .- 1879-3142. ; 64, s. 42-52
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Tidskriftsartikel (refereegranskat)abstract
- The accurate quantification of low-concentration sulfur-containing compounds is essential for the biogas and natural gas industries. We review literature data for the stability of these compounds in standard gas mixtures when sampled in cylinders with different passivations, sample bags, sorbent tubes, solid-phase microextraction and glass sampling bulbs, and we present new data obtained at our three National Measurement Institutes. We show that losses of sulfur-containing compounds are minimized when using passivated sampling cylinders, and the most suitable sorbent material for sampling these compounds is Tenax TA. We also discuss methods for transferring gas from sample vessels to analyzers and give recommendations for the selection of regulators (and other pressure-reducing devices) and transfer lines. Further, we propose approaches that could be taken to reduce or correct for losses in order to provide more accurate measurements of sulfur-containing compounds.
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