IRMM-3100a: A new certified isotopic reference material with equal abundances of 233U, 235U, 236U and 238U

The new so-called Quad-IRM (“Quadruple Isotope Reference Material”) was prepared from highly enriched 233U, 235U, 236U and 238U isotopic materials using an optimized combination of gravimetrical mixing and mass spectrometry. Within the mixing process the isotope ratios were adjusted to about n(233U)/n(235U)/n(236U)/n(238U)=1/1/1/1 and certified with expanded relative uncertainties of 0.0054% per mass unit (coverage factor k=2). This new isotope reference material is ideal for verifying the inter-calibration of multi-detector systems in isotope mass spectrometry.