Yao Yang,Maoyi Luo,Yang Wu,Ni Yuan,Jingjing He,Hongmei Guo,Quan an
A reliable and stable method was developed to accurately analyze neptunium ( 237 Np) and plutonium isotopes in environmental samples using 242 Pu or 236 Pu as a tracer. Key parameters, including the valence adjustment conditions and the stabilities of Pu and Np in the different resins, were investigated using TK200 and TEVA resin. It was found that Pu and Np could be efficiently extracted simultaneously using TK200 resin under the optimal loading conditions (6–12 M HNO 3 ) with the addition of 0.01–0.12 M NaNO 2 for valence adjustment. These isotopes were subsequently stripped out using a solution containing 0.1 M HCl , 0.05 M HF, and 0.01 M NH 2 OH·HCl. The separation efficiencies of Pu and Np were >93%, and the chemical yield ratio between Np and Pu was maintained steady at an average of 1.00 ± 0.03 (n > 50) under the optimal conditions. The analytical method was validated by analyzing environmental soil samples spiked with known amounts of 239 Pu and 237 Np standard solutions or certified reference materials. The measured values of 237 Np, 239 Pu, and 240 Pu obtained by inductively coupled plasma tandem mass spectrometry were consistent with their International Atomic Energy Agency literature values within a 95% confidence interval. These results confirm the reliability and high analytical precision (<6%) of this developed method using Pu as a non-isotopic tracer for monitoring the chemical yield of 237 Np. The developed method can also be used for environmental pollutant monitoring and for tracer studies of the 237 Np and Pu isotopes.
Plutonium has been extensively studied in the environment, for the purpose of radiological assessment, environmental behavior study and nuclear emergency response. To determine Pu isotopes in environmental soil and sediment, a novel analytical method was established in this study using a new type of extraction resin, TK200 resin. Firstly an investigation was performed to study the extraction behaviors of Pu, U, Th, Hg, Tl, Pb, Bi and Hf on TK200 resin. On the basis of the results, a new chromatographic procedure was then proposed to separate Pu from the elements that interfere the accurate determination of Pu isotopes by mass spectrometry. Owing to the excellent separation efficiency between Pu and interfering elements (IEs) of the developed procedure, high decontamination factors (DFs) were obtained for IEs, e.g. the DF(U) (>7.5 × 10 7 ) was the highest reported value. The separation procedure was finally combined with HNO 3 leaching, CaF 2 /LaF 3 coprecipitation and sector field-inductively coupled plasma mass spectrometry (SF-ICPMS) measurement to establish a complete method. The established method was evaluated by analyzing four standard reference materials (soil, sediment), and the results showed that both 239+240 Pu activity and 240 Pu/ 239 Pu isotopic ratio were accurately determined, with stable and high Pu chemical recoveries (81–91%). The whole analytical method only took about 15 h, and the limits of detection were calculated to be 0.13–0.24 fg g −1 for Pu isotopes (for 2 g soil or sediment), guaranteeing the rapid determination of ultra-trace level Pu in soil and sediment samples.
A rapid, accurate, and sensitive inductively coupled plasma mass spectrometry (ICP-MS) method has been developed and validated for the determination of ultra-trace levels of Plutonium-239 ( 239 Pu) in food. After ashing, samples were digested with lefort aqua regia and treated with FeCl 3 to mask phosphorus (P) interference, thereby preventing it from inhibiting the adsorption of Pu by the resin column. Subsequently, a two-stage TK200 resin column was employed for separation and purification, followed by ICP-MS analysis using kinetic energy discrimination (KED) mode. By combining a chromatographic column with ICP-MS, this method achieved an overall decontamination factor (DF) of 3.53×10 12 for uranium hydride ions ( 238 UH + ) and demonstrated excellent linearity within the given concentration range, with a correlation coefficient ( r ) exceeding 0.999. The limit of detection (LOD) was 3.6 fg/g (ash), with an average recovery of over 74% and a relative standard deviation below 6.6%. Furthermore, the proposed method's applicability was evaluated by quantifying 239 Pu in food. The results indicate that this method is rapid, accurate, and sensitive, making it ideal for 239 Pu detection.
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