Simple and rapid method for 236U/238U isotope ratio analysis in soil and sediment by alkali fusion and thermal ionization mass spectrometry

Currently, there is an increasing demand for simple, rapid, and accurate analytical methods for analyzing 236 U and 236 U/ 238 U isotope ratios in the swipe, nuclear accident, or environmental samples. In response to the complexities inherent in traditional methodologies and the high uncertainty associated with analytical techniques, we developed a rapid method that integrates alkali fusion with thermal ionization mass spectrometry. This method addresses the shortcomings of traditional methods, especially the issue of sample pretreatment efficiency. The efficacy and practicality of the developed method are demonstrated by eliminating the ashing process, reducing evaporation, and direct purification. After parameter optimization, the uranium recovery exceeded 80 %, and the pretreatment process was completed within 7 h for a batch of samples. We tested the method's stability and applicability by analyzing the certified and IAEA reference materials and found that it was suitable for various environmental samples. The measurement of the 236 U/ 238 U isotope ratio and 236 U concentration were achieved using the developed thermal ionization mass spectrometry method. The method was validated using IRMM 184 with an accuracy of 0.11 %. The developed pretreatment and instrumental method were applied to IAEA reference materials, and the measured 236 U/ 238 U isotope ratios and 236 U concentrations were consistent with the reported values. This method can be directly used in scenarios requiring rapid analysis and high-precision measurement of uranium isotopes.