LIGHT STABLE ISOTOPE PROGRESS REPORT: UPDATED CARBON AND OXYGEN VALUE ASSIGNMENTS AND NEW CONTINUOUS FLOW ORGANIC REFERENCE MATERIALS

Isotope reference materials (RMs) are used across many scientific, industrial and environmental disciplines in order to relate the measured isotopic ratios of samples to stated reference values. The suite of light stable isotope reference materials are administered under the auspices of the International Atomic Energy Agency (IAEA), and are distributed internationally by the IAEA and in North America by the National Institute of Standards and Technology (NIST). The NIST/IAEA Intercomparison Exercise, organized in 2000 and completed in 2003, provides a general model for future intercomparisons, regardless of the isotopic or chemical species of interest. We report here details of this intercomparison exercise and communicate the NIST recommended value assignments and uncertainties for the suite of carbon and oxygen stable isotope reference materials.

Additionally, we introduce a new suite of organic and inorganic materials specifically targeted for, but not limited to, continuous flow applications. Preliminary isotopic values of d15N, d18O,and d17O (Böhlke, J. K et al., 2003) and d34S, Soufre de Lacq, RM 8553 (Qi, Haiping., et.al., 2003 ) have been recently published. Value assignments for two additional materials, glutamic acid and caffeine are currently in progress.