Towards an automated approach for rapid separation of actinides using a liquid handling system

Abstract

The rapid, high-precision determination of actinide isotopic compositions is critical for nuclear forensics, safeguard verification, and environmental assessment, yet these applications are often limited by multi-day chemical preparations and dependence on specialized labware. In this work, we develop a micro-scale dissolution and extraction chromatography workflow that reduces sample preparation times for U, Pu, Np, and Am to a few hours while maintaining isotopic accuracy suitable for high-precision MC-ICP-MS/MS analysis. Small-mass aliquots of geologic and reference materials (0.2–3 mg) and pre-digested SRM solutions are purified using 0.1 mL UTEVA microcolumns, with AG1-X4 and stacked UTEVA-DGA microcolumns used in separate experiments. Custom 3D-printed microcolumns and holders mounted on a repurposed liquid-handling platform deliver reagents under positive pressure, enabling rapid, automated microchemistry without a dedicated commercial extraction-chromatography system. Across a suite of NIST SRMs and glass standards, automated micro-UTEVA separations yielded U recoveries of 4–111% and Pu recoveries of 47–110%, which, although spanning a broader range, were generally lower than those obtained from manual gravity driven microcolumns (30–79% and 82–96%, respectively). Regardless, U and Pu isotope ratios from the automated separation remained within approximately 1% of certified values. Neptunium and Am recoveries were lower (typically 16–41%), highlighting areas for further optimization of the multi-actinide protocol. End-to-end workflows combining microdissolution in custom-machined well plates, 3D-printed microcolumns, and MC-ICP-MS/MS analysis were completed in under 4 hours, showing that laboratory-adaptable, platform-agnostic microchemistry on repurposed liquid-handling hardware (Hamilton MicroLab) can deliver high-quality actinide isotope ratios for time-critical nuclear forensics and safeguards.