Determination of 237Np and Pu isotopes in large soil samples by inductively coupled plasma mass spectrometry

A new method for the determination of 237Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of 237Np and Pu isotopes by ICP-MS. 238U can interfere with 239Pu measurement by ICP-MS as 238UH+ mass overlap and 237Np via 238U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1 × 106. Alpha spectrometry can also be applied so that the shorter-lived 238Pu isotope can be measured successfully. 239 Pu, 242Pu and 237Np were measured by ICP-MS, while 236Pu and 238Pu were measured by alpha spectrometry.