@misc{oai:repo.qst.go.jp:00066912,
 author = {Zheng, Jian and Shikamori, Yasuyuki and Wang, Hai and Ni, Youyyi and Huang, Zhaoya and Aono, Tatsuo and 鄭 建 and 黄 召亜 and 青野 辰雄},
 month = {Sep},
 note = {Introduction
In recent years, there has been an increasing demand of ultra-trace determination of radionuclides in studies of nuclear emergency preparedness, nuclear decommissioning,  safeguards and nuclear forensics, and in environmental studies, such as tracing the sources of radioactive contamination, revealing the transport process of aerosols in the atmosphere, and in study of the ongoing environmental changes. 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. In this work, we presented a determination method of ultra-sensitive determination of Pu isotopes in environmental samples by ICP-MS/MS with a high efficiency sample introduction system.
\nMethod
In this method, the ICP-MS/MS (Agilent 8800) combined with an APEX-Q high efficiency sample introduction system (Elemental Scientific Inc, Omaha, NE, USA) was used for the analysis of Pu isotopes (239Pu, 240Pu and 241Pu). An established chemical separation method involving HNO3-HF digestion, CaF2/LaF3 co-precipitation and extraction chromatography (TEVA-UTEVA-DGA) separation was used for the separation of Pu from U, Th and other interferences [1]. 
\nResults and discussion
In order to achieve the ultra-sensitive analysis of Pu isotopes, we evaluated the sensitivity of ICP-MS/MS at three no-gas modes using a U standard solution (1 ng/ml): (1) Single MS; (2) MS/MS and (3) APEX-MS/MS. Fig. 1 showed the obtained sensitivity and comparison with that of sector-field ICP-MS (SF-ICP-MS).  A factor of 7 sensitivity improvement was achieved using APEX-MS/MS mode. The estimated instrumental detection limit ranged from 0.05 to 0.29 fg/ml for Pu isotopes (239Pu, 240Pu and 241Pu), which is comparable to that of APEX-SF-ICP-MS [2]. The UH+ formation was found at 4x10-5 level. The method was validated by analysis of sediment reference materials. 
\nReferences
1. Z. Wang, J. Zheng, Y. Ni, W. Men, K. Tagami, S. Uchida, Anal. Chem. 89, 2221-2226 (2017).
2. J. Zheng, M. Yamada, Talanta, 69, 1246-1253 (2006)., 日本分析化学会第６７年会},
 title = {Ultra-sensitive determination of Pu isotopes in environmental samples by ICP-MS/MS with a high efficiency sample introduction system},
 year = {2018}
}