Rapid isotopic analysis of uranium microparticles via SP-ICP-TOF-MS
Stanberry et al.
Talanta, 2026
DOI: 10.1016/j.talanta.2025.128578
A study published in Talanta led by researchers from Oak Ridge National Laboratory, and with contributions from TOFWERK showed the use of single-particle inductively coupled plasma time-of-flight mass spectrometry (SP-ICP-TOFMS) to measure uranium isotope ratios in depleted, natural, and low-enriched uranium oxide microparticles with high accuracy. The method employing a TOFWERK icpTOF R enabled simultaneous detection of uranium and matrix particles (e.g., Al, Fe, Ti) in complex suspensions, demonstrating its high-throughput capability for uranium isotope analysis in a challenging matrix.
Since the 1990s, the IAEA has used environmental sampling to detect undeclared nuclear materials, traditionally analyzed by bulk or particle-based mass spectrometry methods like large geometry secondary ion mass spectrometry (LG-SIMS) and fission track thermal ionization mass spectrometry (FT-TIMS), which offer precision but suffer from low throughput. Laser ablation ICP-MS improved speed, but limitations remain. This study demonstrated the first use of single-particle ICP-TOFMS for uranium isotope analysis, offering high-throughput, multi-element detection and the ability to differentiate depleted, natural, and low-enriched uranium particles for safeguards and forensics.
Uranium particles (depleted uranium (DU), natural uranium (NU), and low-enriched uranium (LEU) were characterized using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and analyzed by SP-ICP-TOFMS with a notch filter to prevent detector saturation from intense ²³⁸U signals. Notch calibration with standards enabled accurate ²³⁵U/²³⁸U ratio correction, though DU showed larger deviations due to low counts and limited particles. Despite higher RSDs, particles with sufficient ²³⁵U counts (>20) yielded reliable isotope ratios. In complex mixtures such as a simulated soil matrix (Arizona Test Dust), SP-ICP-TOFMS distinguished uranium particles from matrix particles, classifying DU and NU when >23 counts of ²³⁵U were present.
SP-ICP-TOFMS characterized 1 μm uranium particles (DU, NU, LEU) via their ²³⁵U/²³⁸U ratios, achieving relative differences below 10% and accurate detection even for low ²³⁵U counts. The method distinguished DU and NU in complex matrices, classifying 30.1% of uranium particles, and offers high-throughput analysis, making it a faster, promising alternative to labor-intensive techniques like FT-TIMS and LG-SIMS for environmental and nuclear safeguards applications. Its ability to simultaneously detect multiple isotopes in thousands of individual particles within minutes highlights the unique power of the icpTOF.
