ABSTRACT The use of stable isotopes (δ 2H and δ 18O) is widespread in water resources studies. In the Latin America and the Caribbean (LAC) region, the application of isotope techniques has increased in the past decade, but there remains room to gain self-reliance in environmental isotope studies, necessitating easy and fast access to good-quality isotope data. To that end, in 2018 the IAEA carried out the first regional interlaboratory comparison exercise, testing the analytical performance of 25 laboratories using isotope-ratio mass spectrometry and laser absorption spectroscopy. The three test samples covered a commonly observed range of 0 to –16 ‰ δ 18O and 0 to –115 ‰ δ 2H. z- and ζ-scores were used to benchmark laboratories’ performance against a strict criterion. We found that 81% of the laboratories had satisfactory performance ( ≤ 2) for δ 2H but only 54% achieved similar scores for δ 18O. Only a minor fraction of results (12% for δ 2H and 15% for δ 18O) were unsatisfactory. The larger number of questionable results for δ 18O confirmed the challenges in laser absorption spectroscopy for this isotope. Besides instrumental performance, the sample throughput, laboratory reference materials, and data post-processing were contributing factors to inaccurate or imprecise performance.

中文翻译：

---

原子能机构在拉丁美洲和加勒比地区进行的首次水样稳定同位素分析实验室间比较活动

摘要 稳定同位素（δ 2H 和 δ 18O）在水资源研究中广泛使用。在拉丁美洲和加勒比 (LAC) 地区，同位素技术的应用在过去十年有所增加，但在环境同位素研究中仍有自力更生的空间，因此需要轻松快速地获取高质量的同位素数据。为此，原子能机构在 2018 年开展了第一次区域实验室间比对活动，使用同位素比质谱法和激光吸收光谱法测试了 25 个实验室的分析性能。三个测试样品涵盖了 0 至 –16 ‰ δ 18O 和 0 至 –115 ‰ δ 2H 的普遍观察范围。z 和 ζ 分数用于根据严格的标准对实验室的表现进行基准测试。我们发现 81% 的实验室在 δ 2H 方面的表现令人满意（≤ 2），但只有 54% 的实验室在 δ 18O 方面取得了相似的分数。只有一小部分结果（δ 2H 为 12%，δ 18O 为 15%）不令人满意。δ 18O 的大量可疑结果证实了该同位素激光吸收光谱的挑战。除了仪器性能外，样品通量、实验室参考材料和数据后处理也是导致性能不准确或不精确的因素。