Stability monitoring of selected spike isotopic reference materials for isotope dilution mass spectrometry

The provision of high quality spike isotopic reference materials is one of the objectives of the Joint Research Centre of the European Commission. They play an important part in measurements of nuclear materials for Nuclear Safeguards. Spike isotopic reference materials are prepared and certified according to the international standards. The assigned values for the isotope amount content and isotope ratios need to be verified at regular intervals. This is carried out by stability monitoring measurements. This paper will discuss the results of the stability assessment of some ²⁴²Pu and ²⁴³Am spike isotopic reference materials. (author)