Gas Sensing Metrology Group, Chemical Sciences Division, Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
Lyn Software, 7620 Irongate Lane, Frederick, MD, 21702, USA.
Anal Bioanal Chem. 2018 Sep;410(24):6247-6255. doi: 10.1007/s00216-018-1235-z. Epub 2018 Jul 6.
The noble gases, namely neon, argon, krypton and xenon, have many uses including in incandescent and gas discharge lighting, in plasma televisions, shielding gas in welding, in lasers for surgery and semiconductors, and in magnetic resonance imaging (MRI) of the lungs. When incorporating these noble gases in industries, especially the medical field, it is important to know accurately the composition of the noble gas mixture. Therefore, there is a need for accurate gas standards that can be used to determine the noble gas amount-of-substance fraction in the appropriate mixture application. A recent comparison of mixtures containing four noble gases in a helium balance showed mixed results among National Metrology Institutes. Significant differences, 0.7 to 3.8% relative, were seen in the analytical amount-of-substance assignments versus the gravimetric value of the noble gases in the comparison mixture when using "binary standards", i.e. neon in helium, argon in helium and krypton in helium, as applied by the National Institute of Standards and Technology. Post-comparison studies showed that when all four noble gases were included in the standards, the agreement between analytical and gravimetric values was within 0.05% relative. Further research revealed that different carrier gases (hydrogen, helium and nitrogen) resulted in varying differences between the analytical and gravimetric values assignments. This paper will discuss the findings of these analytical comparisons. Graphical abstract ᅟ.
稀有气体，如氖、氩、氪和氙，有许多用途，包括白炽灯和气体放电灯、等离子电视、焊接保护气体、手术和半导体激光器以及肺部磁共振成像（MRI）。在将这些稀有气体纳入工业，特别是医疗领域时，准确了解稀有气体混合物的组成非常重要。因此，需要使用能够准确确定适当混合物应用中稀有气体物质分数的精确气体标准。最近对氦平衡中含有四种稀有气体的混合物进行的比较表明，国家计量研究所之间的结果存在差异。在使用“二元标准”（即氦中的氖、氦中的氩和氦中的氪）时，与比较混合物中稀有气体的重量值相比，分析物质分数的赋值与重量值之间存在显著差异，相对差异为 0.7 到 3.8%。 比较后的研究表明，当所有四种稀有气体都包含在标准中时，分析值和重量值之间的一致性在 0.05%相对范围内。进一步的研究表明，不同的载气（氢、氦和氮）导致分析值和重量值赋值之间存在不同的差异。本文将讨论这些分析比较的结果。
