Rapid sequential determination of americium and plutonium in sediment and soil samples by ICP-SFMS and alpha-spectrometry

An improved sample preparation method for the determination of americium and plutonium in sediment and soil samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and alpha-spectrometry is described. The developed procedure involves a selective CaF2 co-precipitation for pre-concentration and matrix removal followed by a sequential extraction chromatographic separation. The average chemical recovery of sample preparation was between 81%-94% for both americium and plutonium. The method development also focused on the elimination of possible interferences in mass spectrometric analysis caused by molecular ions (e. g. (UH+)-U-238-H-1, (PbAr+)-Pb-204-Ar-36 or (PbO2+)-Pb-208-O-16) employing the suitable matrix separation prior to ICP-SFMS analysis coupled with a desolvation sample introduction system. For Pu-239, Pu-24, Pu-241 and Am-241 limits of detection of 15, 9.2, 14 and 23 fg g(-1) was achieved by ICP-SFMS, respectively. The applied sample preparation and measurement can be carried out within 6 h for one batch of samples. Results of certified reference materials (IAEA-384 and IAEA-385) analysed by the two different measurement techniques agreed well with the recommended or information values.