Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

TLDR

Since the 1950s, the number of international stable‑isotope reference materials has expanded from a handful to over 150, covering more than 25 elements and reflecting rapid growth in measurement standards and instrumentation. The report urges authors to publish the delta values of secondary reference materials used to anchor their results to primary scales and notes that primary standards remain required for elements such as Mg, Fe, Te, Sb, Mo, and Ge.

Abstract

Abstract Since the early 1950s, the number of international measurement standards for anchoring stable isotope delta scales has mushroomed from 3 to more than 30, expanding to more than 25 chemical elements. With the development of new instrumentation, along with new and improved measurement procedures for studying naturally occurring isotopic abundance variations in natural and technical samples, the number of internationally distributed, secondary isotopic reference materials with a specified delta value has blossomed in the last six decades to more than 150 materials. More than half of these isotopic reference materials were produced for isotope-delta measurements of seven elements: H, Li, B, C, N, O, and S. The number of isotopic reference materials for other, heavier elements has grown considerably over the last decade. Nevertheless, even primary international measurement standards for isotope-delta measurements are still needed for some elements, including Mg, Fe, Te, Sb, Mo, and Ge. It is recommended that authors publish the delta values of internationally distributed, secondary isotopic reference materials that were used for anchoring their measurement results to the respective primary stable isotope scale.