Challenges in preparing soil samples and performing a reliable plutonium isotopic analysis by ICP-MS

Soil samples were prepared by performing ion exchange and extraction chromatography separation techniques and measured in the low resolution mode (m/Delta m = 300) using a standard nebulizer (1 mL/min, U-type, "Glass Expansion") and a cyclonic 50 mL spray chamber. With this configuration if plutonium concentration is in a sub-ppt range, (UH+)-U-238-H-1 must be taken into the account; however, taking into the account (UHH+)-U-238-H-1-H-1 is not necessary. In all cases it is strongly recommended to avoid using hydrochloric acid as a final stabilizing matrix and use the ultrapure nitric acid as it creates the lowest background at 239 and 240 m/z values.