Highly efficient and accurate analysis of ultra-trace anthropogenic 236U in the presence of natural uranium isotopes is essential for nuclear forensics and environmental monitoring. In this study, we developed an integrated analytical method for the determination of 234U, 235U, 236U, and 238U by combining highly automated sample preparation with highly sensitive ICP-MS/MS detection. Automated total dissolution was employed to ensure complete extraction of both endogenous and exogenous uranium from solid matrices, while reproducible chemical separation was achieved using an automated platform equipped with regenerable UTEVA resin. This optimized procedure yielded exceptionally low operational blanks for 236U at femtogram level. Moreover, the final eluent volume was minimized to 1.5 mL, allowing direct introduction into the ICP-MS/MS. By utilizing a membrane desolvation sample introduction system and a novel mass-shift mode (targeting UO2+ species), the ICP-MS/MS sensitivity exceeded 4.1 × 106 cps/ppb, while the 235UH + interference formation rate for 236U was suppressed to 7.1 × 10-10. Consequently, the achieved detection limits for 236U and the 236U/238U atom ratio were as low as 1.85 fg/g and 5 × 10-12, respectively. This method was successfully applied to determine the uranium isotopic composition in sediments from the adjacent sea area of the Daya Bay Nuclear Power Plant. These results demonstrate that the proposed method provides a robust and high-throughput solution for accurately quantifying of ultra-trace 236U in environmental samples, such as those impacted by the global fallout.

The analysis of 241Am in environmental samples is of great importance in the fields of geological repositories and radiation protection. The triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) has a strong analytical and interference removal capability for long half-life radionuclides. In this study, the ability of ICP-MS/MS to determine ultra-trace level of 241Am in environmental samples was further explored. The instrumental sensitivity for Am detection was significantly improved (ca. 20 times) by employing an APEX-omega high efficiency introduction system. The gases of O2 and He were introduced to the reaction cell for eliminating of interferences and Am was detected as AmO+ ions. High separation factors (>2000) of Am and Pu were ob-tained at proper gas flow rates by chemical resolution of the instrument. Meanwhile, the background signals caused by possible polyatomic interferences for 241Am and 243Am were sufficiently reduced. A simple and rapid chromatographic separation method for purposeful and efficient separation of 241Am from matrix and interfering elements was developed. The overall chemical recoveries were about 68% and the detection limit of 241Am for the established method was 0.18 fg g-1 (equivalent to 0.02 mBq g-1). Several marine sediment reference ma-terials were analyzed for the validation of the method and the results showed that this method was suitable for the determination of 241Am in solid environmental samples. The method was finally applied to real marine sediment samples collected in the western North Pacific after the Fukushima nuclear accident.

U, Sr, Pb, Nd, and Hf isotope ratios can provide basic and important information of nuclear materials. We established a simple and efficient column chemistry method using nano-NaBiO3, as both oxidizer and adsorbent, to completely separate Ce from rare earth elements (REEs). This new method exhibited a high decontamination (Ce/Nd < 10(-5)) ability and was easy to conducted, thereby providing clear advantages compared to traditional liquid-liquid and solid phase micro-extraction techniques. Additionally, a rapid four-column separation procedure, based on Sr, TUR, Ln resins and nano-NaBiO3, was developed to isolate U, Sr, Pb, Nd, and Hf in ore samples. The entire procedure could be completed in 4-5 hrs. The robustness of the proposed method was demonstrated by analyzing the U-235/U-238, Sr-87/Sr-86, Pb-206/Pb-204, Pb-207/Pb-204, Pb-208/Pb-204, Nd-142/Nd-144, Nd-143/Nd-144, and Hf-176/Hf-177 isotopic ratios of two certified reference materials (CRMs). The analytical results obtained using this method showed good agreement with previously published data. The feasibility of this method was extended to the determination of isotope ratios in uranium ores. The results obtained from the two samples with different regions indicated that they have different isotopic ratios information. These findings indicate the potential for the use of this new method in nuclear forensic science.

Origin assessment of nuclear materials is the key aim of nuclear forensics. Among the various fingerprints, rare-earth elements (REEs) are regarded as a powerful geological signature in authentication studies as they behave similarly during geologic and mining/milling processes. In this study, the combination of rare-earth impurities and Nd–Ce isotope ratios were proposed as a novel fingerprint for the origin assessment of uranium ores. A database was established, comprising mass spectrometric measurements of rare-earth elemental parameters of twenty-five samples from seven countries. The efficiencies of different multivariate statistical techniques, including cluster analysis (CA), principal component analysis (PCA) and linear discriminant analysis (LDA), were compared. The results showed that most of uranium ore samples were correctly classified according to geographical origins, and Nd–Ce isotope ratios played a key role in improving the classification. High recognition (100%) and satisfactory predictive ability (90%) of the developed LDA model proved that the proposed method is a powerful tool for tracing unknown uranium ore samples.

The extraction and accurate analysis of U are of great significance for environmental monitoring. In this study, a novel polyethylene-supported phosphonate coordination polymer membrane was fabricated via a facile one-pot method. Its adsorption process was pH dependent. The optimal percentage removal efficiency was close to 90% near neutral conditions, and the maximum adsorption capacity reached 48.6 mg g−1. Moreover, a stable adsorbent and a combined separation–assay method for uranium from neutral condition were achieved. This study provides new insights into the fabrication and application of functionalized polymer membranes that are viable for the analysis of radionuclides in real scenarios.

The analysis of 241Am in environmental samples is of great importance in the fields of geological repositories and radiation protection. The triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) has a strong analytical and interference removal capability for long half-life radionuclides. In this study, the ability of ICP-MS/MS to determine ultra-trace level of 241Am in environmental samples was further explored. The instrumental sensitivity for Am detection was significantly improved (ca. 20 times) by employing an APEX-Ω high efficiency introduction system. The gases of O2 and He were introduced to the reaction cell for eliminating of interferences and Am was detected as AmO+ ions. High separation factors (> 2000) of Am and Pu was obtained at proper gas flow rates by chemical resolution of the instrument. Meanwhile, the background signals caused by possible polyatomic interferences for 241Am and 243Am were sufficiently reduced. A simple and rapid chromatographic separation method for purposeful and efficient separation of 241Am from matrix and interfering elements was developed. The overall chemical recoveries were about 68% and the detection limits of 241Am for the established method was 0.18 fg g-1 (for 1 g sediment sample). Several marine sediment reference materials were analyzed for the validation of the method and the results showed that this method was suitable for the determination of 241Am in solid environmental samples. The method was finally applied to real marine sediment samples collected in the western North Pacific after the Fukushima nuclear accident.

Analysis of trace impurities in uranium materials is crucial for quality control in the nuclear industry and also informative for nuclear forensics. Herein we developed a rapid and high efficient method for accurate determination of 15 impurity elements (Al, Ti, Cr, Mn, Fe, Ni, Zn, Zr, Nb, Mo, Ru, Sn, Sb, Pb, Th) in uranium materials by combining chemical separation with matrix matched external calibration measurement. Uranium sample was digested, separated with the UTEVA resin and directly diluted for ICP-MS/MS measurement under optimized He collision mode. Recoveries of all the impurities exceed 90%, most of which were more than 95%. The interelement inferences as well as the solution matrix effects on the impurity signals were investigated. The ICPMS/MS detected signals of Zn and Sb that have high first ionization potentials were relatively more susceptible to the solution matrix compared with other impurity element signals, and thus highlighted the necessity of solution matrix matched between sample and external calibration standards. The detection limits of the proposed method ranged from ng/g to mu g/g level for different impurities. The method was validated and further applied to bulk uranium ore samples. Large variation of some impurities such as Mn, Zr, Nb. Pb and Th among different ore samples were observed, which might be attributed to their different origins.

Expanding the ability of ICP-MS/MS for the determination of Pu isotopes in environmental samples.

A new method is presented for high-precision measurement of cerium isotope ratios in geological samples by TIMS with the Ce+ technique.

Pt filaments with Ba(OH)2 as the ionization activator were highlighted for the measurement of Tc by N-TIMS.

Neodymium isotope analysis as Nd+ ions is more favored than as NdO+ ions due to less potential isobaric interferences and no need for complicated oxygen isotope corrections. However, the poor sensitivity and inadequate reproducibility seriously hinder its application. In this study, a new analytical method by thermal ionization mass spectrometry (TIMS) is initially presented for the precise measurement of Nd-143/Nd-144 ratio as Nd+ ions with film porous ion emitter (FPIE), combined with a simplified Nd chemical separation procedure. The Nd+ ion yields were one order of magnitude higher than those of traditional Nd+ ion analysis method. Repeated measurements of reference material JNdi-1 (1 ng) yielded a Nd-143/Nd-144 value of 0.512113 +/- 33 (2SD, n = 9). The achieved external precisions fulfilled the requirements for applications in nuclear forensics. Rock powder reference materials and uranium ore samples were analyzed to further test the accuracy and reproducibility of our method. We believe that this method is not only a particular value for nuclear forensic purposes, but also can expand the applications of Nd isotope ratio analysis in geochemistry, geochronology and environmental sciences.

A new method was developed for determination of the 135Cs/137Cs isotopic ratio at the femtogram level in environmental samples.

In this study, an advanced method has been developed to identify uranium-bearing particles through fission track and make the particles and fission track detector form a whole. This method can result in the one-to-one correspondence between the fission track and uranium-bearing particles. It is unnecessary to separate the particles from the detector and relocate the particles when they are picked up under microscope. This simple identification is helpful in reducing the loss of particles, which would be picked up and transferred to mass spectrometer for analysis.

The radioactive fission products 135Cs, 137Cs and 90Sr have been released into the environment by human activities such as nuclear weapon tests, nuclear fuel reprocessing and nuclear power plant accidents. Monitoring of these radionuclides is important for dose assessment. Moreover, the 135Cs/137Cs isotopic ratio can be used as an important long-term fingerprint for radioactive source identification as it varies with weapon, reactor and fuel types.

An extraction system with annular centrifugal extractors has been designed to separate plutonium.It worked well when centrifugal speed was ranged from 2000 to 8000 r/min and organic-aqueous flow ratio(o/a) ranged from 1/3 to 1,without obvious entraining phenomenon.Pu(IV) in 6 mol/L HNO3 solution was fast extracted and separated,using 0.1 mol/L TOPO/Cyclohexane as extraction solvent and 0.01 mol/L oxalic acid as back extraction solvent.The extraction ratio of two stages was larger than 90%,and the back ratio per stage was more than 96%.The extraction system shows fast operating speed and high extraction ratio,therefore it is suitable for fast extracting Pu.