A new generation of multi-collector IRMS, utilizing both inductively coupled plasma and thermal ionization sample sources, is now capable of measuring isotope ratios with extremely high precision – a few parts in 106. This new measurement capability has caused a minor revolution in the use of isotopes by revealing small but significant isotopic variations in nearly all non-radiogenic poly-isotopic elements, many of which had been previously thought to have fixed isotopic abundances. These new measurements have also revealed not only mass dependent isotopic fractionations but also mass independent fractionations for selected elements. Isotopic variations are now being intensively studied in a considerably expanded research realm, for example chemical processes associated with the effects of human activities on the earth's ecosystems. Health, nutritional, and biochemical studies are also benefiting from the specificity of the high-precision isotopic measurements by enabling the non-invasive study of specific metal and protein uptake mechanisms and dose/response relationships in humans. Forensic and homeland security applications identifying adulteration and commodity provenance are also being vigorously pursued.
Currently, the analytical community is struggling to separate isotopic effects resulting from biases in the analytical measurement process from scientifically valid isotopic signatures resulting from natural processes. Producing a set of high-quality isotopic reference materials (RMs) should directly improve the quality and reliability of such measurements. This program will have an impact in several measurement sectors including:
- Medical – improved performance/specificity of clinical studies (e.g. calcium and osteoporosis, iron and hemochromatosis).
- Ecological – improved understanding of mass flux in natural systems and biogeochemical cycling of environmental pollutants to more rigorously guide models used for policy-making.
- Forensics – drug, food, and flavor provenance as well as identifying counterfeiting.
- Global Warming/Heavy Metal Cycling – refining and advancing global models of climate, photochemistry, and pollutant cycling due to climate change.