Skrzypek Grzegorz, Dunn Philip J H
West Australian Biogeochemistry Centre, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Perth, Western Australia, 6000, Australia.
National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex, TW11 0LY, UK.
Rapid Commun Mass Spectrom. 2020 Oct 30;34(20):e8890. doi: 10.1002/rcm.8890.
The isotope delta is calculated from the isotope ratio of a sample and the absolute isotope ratio of the zero reference point defining each stable isotope international scale (R ). Therefore, R requires accurate determination. However, the literature contains a large number of R values, and selection of different R may lead to inconsistency in reporting and recalculating stable isotope results.
We reviewed R used in the proprietary software provided by the manufacturers of stable isotope instruments commonly employed for analyses of stable HCNOS compositions. We compared the R values and assessed the potential implications of using different R and the normalization versus tank working gas standard for consistency in reporting stable isotope results.
Different R values are used by different manufacturers of stable isotope analytical instruments. For R( H/ H) two different but very similar values are used, 0.00015575 and 0.00015576; for R( C/ C) three different values are used, 0.0111802, 0.0112372 and 0.01118028; and for R( N/ N) two values, 0.0036782 and 0.0036765, are used. All manufacturers are using the same value for R( O/ O) , 0.00200520, but three different values for R( O/ O) , 0.002067200, 0.00208835 and 0.002088349. For R( S/ S) four different R are used, 0.0441509, 0.0441626, 0.044162589 and 0.0441520597.
The use of different R values may lead to differences in the isotope delta values obtained if the normalization versus working standard gas is applied. For the range of R used in proprietary software, the potential differences are lowest for oxygen (< 0.002 ‰) and nitrogen (< 0.001 ‰), and highest for carbon (0.107 to 0.112 ‰) and sulfur (0.023 ‰). Evaluation of the existing R values and recommendations for the best estimates are highly desirable to ensure worldwide consistency in stable isotope data reporting.
同位素δ值是根据样品的同位素比率与定义每个稳定同位素国际标度的零参考点的绝对同位素比率（R）计算得出的。因此，需要准确测定R值。然而，文献中包含大量的R值，选择不同的R可能会导致稳定同位素结果报告和重新计算的不一致。
我们回顾了常用于分析稳定HCNOS组成的稳定同位素仪器制造商提供的专有软件中使用的R值。我们比较了这些R值，并评估了使用不同R值以及归一化与气瓶工作气体标准对稳定同位素结果报告一致性的潜在影响。
不同的稳定同位素分析仪器制造商使用不同的R值。对于R（H/ H），使用了两个不同但非常相似的值，0.00015575和0.00015576；对于R（C/ C），使用了三个不同的值，0.0111802、0.0112372和0.01118028；对于R（N/ N），使用了两个值，0.0036782和0.0036765。所有制造商对于R（O/ O）都使用相同的值0.00200520，但对于R（O/ O）使用了三个不同的值，0.002067200、0.00208835和0.002088349。对于R（S/ S），使用了四个不同的R值，0.0441509、0.0441626、0.044162589和0.0441520597。
如果应用归一化与工作标准气体，使用不同的R值可能会导致获得的同位素δ值存在差异。对于专有软件中使用的R值范围，氧（<0.002‰）和氮（<0.001‰）的潜在差异最小，碳（0.107至0.112‰）和硫（0.023‰）的潜在差异最大。非常需要对现有的R值进行评估并给出最佳估计的建议，以确保稳定同位素数据报告在全球范围内的一致性。
