The GAWG (Gas Analysis Working Group of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology) has developed an extrapolation scheme to transfer so that the expanded uncertainty as reported in a key comparison to other amount fractions. Typically, such a comparison only addresses one amount fraction level, whereas the relevant service of a national metrology institute usually covers an interval. In this work, we show how, based on empirical evidence and the uncertainty reported in a key comparison, the measurement uncertainty can be predicted over a wide interval. We do so for four components: carbon monoxide, carbon dioxide, propane and methane, and for two matrices, nitrogen and air. The empirical results confirm to a large extent the validity of the extrapolation scheme of the GAWG above 10 mol mol⁻¹. At the same time, our results show that predictions at the ends of the intervals are often providing a conservative value for the expanded uncertainty. We also conclude that the GAWG extrapolation scheme is less suited for CMCs where additional effects (e.g., adsorptivity, reactivity) play a role. Our extrapolation scheme is more flexible and better suited for this purpose. We also note that the GAWG does not perform well if the nominal value of the amount fraction in the key comparison is substantially below 10 mol mol⁻¹.

GAWG（物质含量咨询委员会的气体分析工作组：化学和生物学中的计量学）已经开发了一种外推方案来传输，以便在与其他数量分数的关键比较中报告扩展的不确定性。通常，这样的比较仅针对一个量分数级别，而国家计量机构的相关服务通常涵盖一个区间。在这项工作中，我们展示了如何根据经验证据和关键比较中报告的不确定性，在很宽的时间间隔内预测测量不确定性。我们为四种成分这样做：一氧化碳、二氧化碳、丙烷和甲烷，以及两种基质，氮气和空气。实证结果在很大程度上证实了 10 mol mol 以上 GAWG 外推方案的有效性^-1。同时，我们的结果表明，区间末端的预测通常为扩展的不确定性提供保守值。我们还得出结论，GAWG 外推方案不太适合 CMC，其中附加效应（例如，吸附性、反应性）起作用。我们的外推方案更灵活，更适合此目的。我们还注意到，如果关键比较中的量分数的标称值大大低于 10 mol mol ^-1，则 GAWG 表现不佳。