Laboratory for Air Pollution/Environmental Technology, Empa, Dübendorf, Switzerland.
Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.
Rapid Commun Mass Spectrom. 2022 Jul 15;36(13):e9296. doi: 10.1002/rcm.9296.
Information on the isotopic composition of nitrous oxide (N O) at natural abundance supports the identification of its source and sink processes. In recent years, a number of mass spectrometric and laser spectroscopic techniques have been developed and are increasingly used by the research community. Advances in this active research area, however, critically depend on the availability of suitable N O isotope Reference Materials (RMs).
Within the project Metrology for Stable Isotope Reference Standards (SIRS), seven pure N O isotope RMs have been developed and their N/ N, O/ O, O/ O ratios and N site preference (SP) have been analysed by specialised laboratories against isotope reference materials. A particular focus was on the N site-specific isotopic composition, as this measurand is both highly diagnostic for source appointment and challenging to analyse and link to existing scales.
The established N O isotope RMs offer a wide spread in delta (δ) values: δ N: 0 to +104‰, δ O: +39 to +155‰, and δ N : -4 to +20‰. Conversion and uncertainty propagation of δ N and δ O to the Air-N and VSMOW scales, respectively, provides robust estimates for δ N(N O) and δ O(N O), with overall uncertainties of about 0.05‰ and 0.15‰, respectively. For δ N , an offset of >1.5‰ compared with earlier calibration approaches was detected, which should be revisited in the future.
A set of seven N O isotope RMs anchored to the international isotope-ratio scales was developed that will promote the implementation of the recommended two-point calibration approach. Particularly, the availability of δ O data for N O RMs is expected to improve data quality/correction algorithms with respect to δ N and δ N analysis by mass spectrometry. We anticipate that the N O isotope RMs will enhance compatibility between laboratories and accelerate research progress in this emerging field.
关于氧化亚氮（N 2 O）天然丰度同位素组成的信息支持其源汇过程的识别。近年来，许多质谱和激光光谱技术已经被开发出来，并被研究界越来越多地使用。然而，这一活跃研究领域的进展在很大程度上取决于合适的 N 2 O 同位素参考物质（RMs）的可用性。
在“稳定同位素参考标准计量学”（SIRS）项目中，开发了七种纯 N 2 O 同位素 RM，并由专门实验室针对同位素参考物质对其 N/N、O/O、O/O 比和 N 位偏爱（SP）进行了分析。特别关注 N 位特异性同位素组成，因为这个可测量值既是源分配的高度诊断指标，又具有挑战性，难以分析并与现有标度联系起来。
所建立的 N 2 O 同位素 RM 提供了广泛的δ值分布：δ N：0 至+104‰，δ O：+39 至+155‰，和δ N ：-4 至+20‰。N 向 Air-N 和 VSMOW 标度的转换和不确定度传播分别为δ N（N 2 O）和δ O（N 2 O）提供了稳健的估计，总不确定度分别约为 0.05‰和 0.15‰。对于 δ N，检测到与早期校准方法相比的偏移超过 1.5‰，这在未来应该重新审视。
开发了一套锚定在国际同位素比标度上的七种 N 2 O 同位素 RM，这将促进实施推荐的两点校准方法。特别是，N 2 O RM 的 δ O 数据的可用性有望改善 δ N 和质谱法分析的 δ N 数据质量/校正算法。我们预计，N 2 O 同位素 RM 将增强实验室之间的兼容性，并加速这一新兴领域的研究进展。
