@misc{oai:repo.qst.go.jp:00074818,
 author = {Zheng, Jian and Wang, Hai and Huang, Zhaoya and Ni, Youyi and Aono, Tatsuo and Zheng, Jian and Aono, Tatsuo},
 month = {Mar},
 note = {ICP-MS, as an atom-counting approach that counts the atoms themselves, irrespective of their decay mode, specific activity, or half-life, is gradually replacing/has replaced conventional radiometric methods, especially, due to its high abundance sensitivity and the ability of removal of polyatomic interference via ion-molecular reaction in the reaction cell, the triple quadrupole ICP-MS (ICP-MS/MS) showed great potential for ultra-sensitive analysis of actinides. 
Sample decomposition is an early and critical part of the analytical procedures which transform Pu into solute form so as to realize subsequent chemical purification before measurement. There are roughly two broad categories of sample decomposition strategies, i.e. acid digestion and fusion. Acid digestion is accomplished using a single acid such as HNO3 or mixed acids such as HNO3-HCl, HNO3-HF and HNO3-HF-HClO4.  Fusion is a useful sample decomposition strategy which is accomplished by heating a mixture of sample and flux to a temperature above the flux melting point. Compared with the conventional acid digestion methods, the times required for fusion methods are reduced to various extents. Additionally, a thorough dissolution of Pu from samples is realizable via a complete decomposition of the sample by fusion with properly selected fluxes. However, due to the high melting point of the commonly used fluxes, most fusion methods in the literature are done in furnaces at high temperatures. 
In this study, a green and rapid analytical method was developed for determination of Pu isotopes in marine sediment samples. The methods consisted of NH4HF2 fusion incorporated with procedure for CaF2/LaF3 co-precipitation, extraction chromatography and ICP-MS/MS measurement. The fusion procedure was done at 250oC on a portable hot plate instead of in a cumbersome muffle furnace and took only 15 min. Chemical recoveries of Pu after completing the NH4HF2 fusion method and chromatographic separation for 0.5-1 g sample were approximately 90%. The NH4HF2 fusion was capable of completely releasing Pu from samples that were pre-ignited at temperatures over 450 oC to 1000 oC, which was comparable to releases obtained by the hazardous and time-consuming HNO3-HF digestion. Additionally, because HF is not used in any procedure of the NH4HF2 fusion, a safer and greener alternative to HNO3-HF digestion is realized for rapid Pu determination in marine sediments collected in Japanese coast after the Fukushima nuclear accident. It takes approximately 8 h for 10 sample analysis (NH4HF2 fusion and sample transferring, 0.5 h; CaF2/LaF3 coprecipitation and filtration, 1.5 h; extraction chromatography and sample preparation, 5.5 h; ICP-MS/MS measurement, 0.5 h) which is less than the conventional acid digestion methods. 
Acknowledgements: This work was supported by the Grant of Fukushima Prefecture related to Research and Development in Radiological Sciences, and the JSPS KAKENHI (Grant number JP17k00537)., The The 20th KEK Symposium on Environmental Radioactivity},
 title = {Low-temperature fusion using NH4HF2 for rapid determination of Pu isotopes by ICP-MS/MS: application for marine sediments collected in Japanese coast},
 year = {2019}
}