Determination of 241Pu in marine samples using co-precipitation with rare earth fluoride and liquid scintillation spectrometry

241Pu was measured in reference materials and marine samples using a novel method based on rare earth fluoride co-precipitation followed by liquid scintillation spectrometry (LSS). Disc sources used for α-spectrometry of 238Pu and 239+240Pu were leached with concentrated nitric acid before neodymium fluoride co-precipitation to scavenge plutonium in the lower oxidation states was carried out. After the determination of the chemical recovery by α-spectrometry, the precipitate was recovered in a H3BO3/HNO3 based dissolver and mixed with Packard Insta-GelO Plus cocktail before LSS. Reasonable agreement has been obtained between the results obtained using this methods and the data obtained by direct disc analysis by LSS and ICP-MS. The 241Pu/239+240Pu ratios were coherent with the expected origin of the Pu contaminant in the marine environment showing the validity of the method.