Determination of plutonium isotopes and neptunium-237 in environmental samples by inductively coupled plasma mass spectrometry with total sample dissolution

A method for the separation and purification of environmental levels of plutonium and neptunium from totally digested sediment samples and determination of isotopic abundances of Np-237, Pu-239, Pu-240 and Pu-241 by ICP-MS has been developed. Data from the analysis of standard reference materials (SRM-4350B, IAEA-135, and IAEA-384), selected sediments collected from the Ob River, Siberia, and laboratory intercomparison analyses conducted with scientists at DOE's Environmental Measurements Laboratory using TIMS are presented and discussed. Chemical recoveries for Pu and Np are 90 and 70 percent, respectively. Measurement precision ranged between 1 and 5 percent for all isotopes except Pu-241, for which it was 10-15 percent. The lower limit of detection was 0.5 fg g(-1) for all isotopes of interest.