Tomoko Haraga

Highly sensitive detection of neodymium ion in small amount of spent nuclear fuel samples using novel fluorescent macrocyclic hexadentate polyaminocarboxylate probe in capillary electrophoresis-laser-induced fluorescence detection.

A rapid and high-sensitive detection method for the total concentration of Nd ion (total Nd) in a small amount of a spent nuclear fuel sample is urgently required since the precise quantification of total Nd ion makes it possible for burnup (degree of fuel consumption) to be determined. In this work, a capillary electrophoresis-laser-induced fluorescent detection method (CE-LIF) is proposed for the analysis of total Nd in a spent fuel sample solution, with the use of a newly synthesized metal fluorescent probe which has a fluorescein and a macrocylic hexadentate chelating group, FTC-ABNOTA, for lanthanide (Ln) ions. Ln ions were derivatized to form a strongly fluorescent complex with the probe to suppress the quenching of the ligand-centered emission. The detection of Ln complexes in the CE-LIF indicated that the interaction between Ln ions and the FTC-ABNOTA was strong enough not to dissociate during migration. The mutual separation among the Ln-FTC-ABNOTA complexes in CE-LIF was achieved by pH control providing a dynamic ternary complexation (DTC) with hydroxide ions. Using the DTC separation mode, a high resolution of Nd from other Ln ions with high resolution of 1.3-1.9 and a theoretical plate number of 68,000, and a very low detection limit of 22 pM (3.2 ppt, 0.11 attomole amount basis) were successfully obtained. A simulated spent fuel sample containing various metal ions was examined in this method with a good quantification result of 102.1% recovery obtained even with a large excess of U.

Simple determination of 99Tc in radioactive waste using Tc extraction disk and imaging plates

A simple method was developed for determination of (99)Tc in low-level radioactive waste: Technetium-99 retained by a solid phase extraction disk was directly measured with imaging plates system. It was found that more than 97% of Tc were retained by the disk from a solution of pH 2 to 12, whereas depth profile of Tc in the disk, which greatly influences the counting efficiency, depended on solution pH. The present method was successfully applied to actual radioactive liquid waste samples arising from nuclear research facilities.

Capillary Electrophoresis With Laser-Induced Fluorescent Detection Method Using Highly Emissive Probes for Analysis of Actinides in Radioactive Wastes

Actinides are important nuclides for the analysis of radioactive wastes arising from nuclear fuel cycle facilities. In order to achieve simple and rapid analysis of actinides, capillary electrophoresis-laser-induced fluorescent detection method (CE-LIF) is one of the potential candidates. In this study, new emissive probes of actinide ions suitable for CE-LIF were developed for the first time. The detection and separation of americium and neptunium ions as model nuclides were examined using several new emissive complexing probes, each of which possessed a fluorophore and a different chelating moiety. With a pre-capillary complexation technique without addition of the probe to separation buffer electrolyte, the highly sensitive fluorescent detection of Am and Np was successfully achieved using acyclic and macrocyclic multidentate probes. The results suggests that the probe with an acyclic hexadentate chelating moiety is suitable for detection and separation of Am and Np. The detection limit of mid–ppt levels was determined.Copyright

Safe and rapid development of capillary electrophoresis for ultratrace uranyl ions in radioactive samples by way of fluorescent probe selection for actinide ions from a chemical library

After the serious nuclear accident at the Fukushima Daiichi Nuclear Power Plant caused by the Great East Japan Earthquake in 2011, the development of feasible, safe, and highly sensitive analytical methods (in terms of low levels of radiation exposure and radioactive waste generation) for radioactive samples, especially actinide (An) ions, represents an important challenge. Here we propose a methodology for selecting appropriate emissive probes for An ions with very low consumption and emission of radioactivity by capillary electrophoresis-laser-induced fluorescence detection (CE-LIF), using a small chemical library of probes with eight different chelating moieties. It was found that the emissive probe L1, which possesses the tetradentate chelating moiety 1,10-phenanthroline-2,9-dicarboxylic acid (PDA), was suitable for detecting uranyl ions. The detection limit for the uranyl-L1 complex using CE-LIF combined with dynamic ternary complexation and on-capillary concentration techniques was determined to be 2.9 × 10-12 M (0.7 ppt). No interference from the large excess of matrix metal ions was observed. This method was successfully applied to real radioactive liquid samples collected from nuclear facilities, including the Fukushima Daiichi Nuclear Power Plant. This strategy not only permitted the development of a safe and rapid analytical method but also provided insight into the coordination chemistry of An ion complexes. Specifically, the PDA structure provided substantial kinetic inertness to its uranyl complex; the formation of a ternary complex between uranyl-L1 and carbonate was revealed; and unusual interactions were observed between the π-electron systems of uranyl and the phenanthroline ring, which stabilized the uranyl-PDA interaction.