A new method using sector field-inductively coupled plasma mass spectrometry (SF-ICPMS) was developed for the determination of (241)Am in large soil samples to provide realistic soil-plant transfer parameter data for dose assessment of nuclear waste disposal plans. We investigated four subjects: extraction behaviors of interfering elements (Bi, Tl, Hg, Pb, Hf, and Pt) on DGA resin (normal type, abbreviated as DGA-N); soil matrix element removal (Mg, Fe, Al, K, Na) using Fe(OH)3, CaF2, and CaC2O4 coprecipitations; Am and rare earth elements (REEs) separation on DGA-N and TEVA resins; and optimization of SF-ICPMS (equipped with a high efficiency nebulizer (HEN)) for Am determination. Our method utilized concentrated HNO3 to leach Am from 2 to 20 g soil samples. The CaC2O4 coprecipitation was used to remove major metals in soil and followed by Am/interfering elements separation using the proposed UTEVA + DGA-N procedure. After a further separation of REEs on TEVA resin, (241)Am was determined by HEN-SF-ICPMS. This method eliminated the matrix effect in ICPMS (241)Am measurement for large soil samples. The high decontamination factors (DFs) of interfering elements enable their thorough removal, and in particular, the DF of Pu (7 × 10(5)) was the highest ever reported in (241)Am studies; thus, this method is capable of analyzing (241)Pu-contaminated Fukushima Daiichi Nuclear Power Plant (FDNPP) sourced soil samples. A low detection limit of 0.012 mBq g(-1) for (241)Am was achieved. The chemical recovery of Am (76-82%) was stable for soil samples. This method can be employed for the low level (241)Am determination in large size soil samples that are contaminated with (241)Pu.

Plutonium is extensively studied in radioecology (e.g., soil to plant transfer and radiological assessment) and geochemistry (e.g., sediment dating). Here, we reported a new chemical separation method for rapid determination of Pu in soil and sediment samples, based on the following investigations: extraction behaviors of interfering elements (IEs, for inductively coupled plasma mass spectrometry (ICPMS) measurement) on TEVA resin; decontamination of U using TEVA, UTEVA, and DGA resins; and the impact of coprecipitation on Pu determination. The developed method consists of four steps: HNO leaching for Pu release; CaF/LaF coprecipitation for the removal of major metals and U; the proposed TEVA + UTEVA + DGA procedure for the removal of U, Pb, Bi, Tl, Hg, Hf, Pt, and Dy; and ICPMS measurement. The accuracy of this method in determining Pu activity andPu/Pu and Pu/Pu isotopic ratios was validated by analyzing five standard reference materials (soil, fresh water sediment, and ocean sediment). This method is characterized by its stable and high Pu recovery (90-97% for soil; 92-98% for sediment) and high decontamination factor of U (1.6 × 10), which is the highest reported for soil and sediment samples. In addition, the short analytical time of 12 h and the method detection limits, which are the lowest yet reported in literature, of 0.56 μBq g (0.24 fg g) for Pu, 1.2 μBq g (0.14 fg g) for Pu, and 0.34 mBq g (0.09 fg g) for Pu (calculated on the basis of a 1 g soil sample) allow the rapid determination of ultratrace level Pu in soil and sediment samples.

An acidic leaching method using HNO3 is widely employed to release the global fallout Pu from soil samples for further chemical separations in radioecology and toxicology studies and in many applications using Pu as a useful tracer. In the method's sample ash treatment step to decompose organic matter in soil, various ashing temperatures (400-900 °C) are used; however, the effect of ashing temperature on the accurate Pu analysis has not been well investigated. In this study, two standard reference soils (IAEA-soil-6 and IAEA-375) were used to determine the ashing temperature effect (from 375 to 600 °C) on the HNO3 leaching method. The Pu analytical results of both standard reference materials showed that lower (239+240)Pu activity was observed when the ashing temperature exceeded 450 °C, and the (239+240)Pu activity continued to decrease as the ashing temperature was raised. Approximately 40% of the Pu content could not be leached out by concentrated HNO3 after ashing for 4 h at 600 °C. The Pu loss was attributed to the formation of refractory materials, which are insoluble in HNO3 solution. This hypothesis was confirmed by the XRD analysis of soil samples, which revealed that plagioclase-like silicate materials were formed after high-temperature ashing. To ensure Pu release efficiency in HNO3 leaching, we recommend 450 °C as the ideal ashing temperature. This recommendation is also useful for analysis of other important artificial radionuclides (e.g., (137)Cs, (90)Sr, (241)Am) for which an ashing process is needed to decompose the organic content in soil samples.

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