Total-reflection X-ray fluorescence determination of thorium and uranium in the presence of interfering elements in solid geological objects of natural and technogenic origin

文献情報

出版日 2023-11-13

DOI 10.1039/D3JA00260H

インパクトファクター 4.023

著者

Timur F. Akhmetzhanov, Tatiana Y. Cherkashina, Alena N. Zhilicheva, Victor M. Chubarov, Galina V. Pashkova

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要旨

The insufficient spectral resolution of the energy-dispersive total-reflection X-ray fluorescence spectrometer (TXRF) makes the quantitative determination of U and Th with the use of Lα lines a challenging task, especially in the case of analysis of natural solid samples with low concentrations of these elements. In this study, we used the PLS regression and the spectrum deconvolution to overcome the peak overlap problem (Th Lα overlaps with Fe Kα + Fe Kα and Rb Kα; U Lα overlaps with Rb Kα and Sr Kα). Samples of rocks, ashes, and ores with different amounts of interfering elements (Rb, Sr, and Fe) were prepared as suspensions for the direct TXRF determination of U and Th. We applied the PLS regression coupled to the special design of experiment (DoE) based on the low-correlated concentrations of U, Th, and Rb in the calibration set of samples. To validate our combination of the DoE, preprocessing procedure and PLS models, we used the independent test sets of the Rb-rich and Rb-depleted samples. Our study revealed that in the presence of considerable line overlapping the deconvolution leads to a significant systematic error (30–60%) within the low concentration range (10–30 ppm), while the PLS regression reduces the systematic error by 2–3 times. Additionally, we demonstrated that the borderline of the semi-quantitative and quantitative determination for the PLS regression is 3 and 10 times lower, respectively. We found that the high RSD of the Th concentrations found by the deconvolution reflects not a poor repeatability of the TXRF measurements, but a poor stability of the deconvolution. The application of the Rb-depleted test set helped us to demonstrate that the PLS regression does not improve the accuracy in the absence of strong line overlapping. In this study, we conclude that the best strategy for the determination of U in the Rb-depleted samples is the implementation of the deconvolution, while the determination of Th and U in the Rb-rich samples is best carried out with the PLS regression.

掲載誌

Journal of Analytical Atomic Spectrometry

CiteScore: 6.2

自己引用率: 25.8%

年間論文数: 254

The Journal of Analytical Atomic Spectrometry (JAAS) is the central journal for publishing innovative research on fundamentals, instrumentation, and methods in the determination, speciation and isotopic analysis of (trace) elements within all fields of application. This includes, but is not restricted to, the most recent progress, developments and achievements in all forms of atomic and elemental detection, isotope ratio determination, molecular analysis, plasma-based analysis and X-ray techniques. The journal welcomes full papers, communications, technical notes, critical and tutorial review articles, editorials, and comments, in addition to the Atomic Spectrometry Updates (ASU) literature reviews that are prepared by an expert panel. Submissions are welcome in the following areas, but note this list reflects the current scope and authors are strongly encouraged to contact the Editorial team if they believe that their work offers potentially new and emerging research relevant to the journal remit: Fundamental studies in the following. New and existing sources for atomic emission, absorption, fluorescence and mass spectrometry and those that provide both atomic and molecular information Sample introduction techniques for solids, liquids, gases Improvements in sensitivity, selectivity, precision, accuracy and/or robustness Isotope ratio measurements, including techniques for improving precision and mass bias correction Single channel and multichannel simultaneous detection systems Chemometrics, statistics, calibration techniques and internal standardisation Theoretical and numerical modelling of fundamental processes related to all of the above methodologies Novel or improved methodologies in areas of application including, but not limited to the following. Biosciences, including elemental, speciation and isotopic analysis in biological systems, immunoassays based on metal-labeled antibodies, bio-imaging, and nanoparticle toxicology Geochemistry Environmental science Materials science, including engineered nanoparticles and quantum dots Metrology, including reference materials Forensic analysis Food and agricultural sciences Energy Archaeometry Molecular analysis. Molecular sources for elemental and isotopic analysis Atomic sources for molecular analysis Atomic and molecular techniques simultaneously used for complementary chemical information All contributions are judged on originality and quality of scientific content, and appropriateness of length to content of new science.