High performance method for determination of Pu isotopes in soil and sediment samples by sector field inductively coupled plasma mass spectrometry

Artificial plutonium in the environment is extensively studied in radioecology (e.g. soil to plant transfer and radiological assessment) and geochemistry (e.g. sediment dating). In this study, a new chemical separation method was developed for rapid determination of Pu in soil and sediment samples, based on the following investigations: extraction behaviors of interfering elements (IEs, for ICPMS measurement) on TEVA resin; decontamination of U using TEVA, UTEVA and DGA resins and the impact of co-precipitation on Pu determination. The developed method consists of four steps: HNO3 leaching for Pu release; CaF2/LaF3 co-precipitation for the removal of major metals and U; the proposed TEVA+UTEVA+DGA procedure for the removal of U, Pb, Bi, Tl, Hg, Hf, Pt and Dy; and ICPMS measurement. The accuracy of this method in determining 239+240Pu activity and 239Pu/240Pu and 241Pu/239Pu atom ratios was validated by analyzing five standard reference materials (soil, fresh water sediment and ocean sediment). This method is characterized by its stable and high Pu recovery (90-97% for soil; 92-98% for sediment) and high decontamination factor of U (1.6 × 107) which is the highest reported for soil and sediment samples. In addition, the short analytical time of 12 h and the method detection limits, which are the lowest yet reported in literature, of 0.56 μBq g-1 for 239Pu, 1.2 μBq g-1 for 240Pu, and 0.34 mBq g-1 for 241Pu (calculated on the basis of a 1 g soil sample) allow the rapid determination of ultratrace level Pu in soil and sediment samples