Unusually kinetically inert monocationic neptunyl complex with a fluorescein-modified 1,10-phenanthroline-2,9-dicarboxylate ligand; Specific separation and detection in gel electrophoresis

Yamagata, Kazuhito*; Ouchi, Kazuki  ; Marumo, Kazuki*; Tasaki-Handa, Yuiko*; Haraga, Tomoko   ; Saito, Shingo*

The inert NpO complex with a fluorescein-modified phenanthroline-2,9-dicarboxylic acid was found by kinetic selection using polyacrylamide gel electrophoresis (PAGE) from a small chemical library. The small spontaneous dissociation rate constant of 810 s (the half-life of 23 hours) was determined. This is the singly-charged NpO complex exhibiting unusual kinetic inertness in aqueous solution, one million times slower than widely accepted fast kinetics of neptunyl complexes. Selective fluorescence detection of NpO was achieved in PAGE with a detection limit of 68 pmol dm(17 fg). This system was successfully applied to simulated spent nuclear fuel and high-level radioactive waste samples.