Determination of trace uranium in ternary-complex system with tri-n-octylphosphine oxide modified electrode

The preparation of tri-n-octylphosphine oxide (TOPO) modified electrode and electrochamical characteristics of uranyl ions on the electrode in the system of HAc-NaAc and thenoyltrifluoraceton (HTTA) are reported. TOPO is attached on the electrode surface by chemical adsorption. Owing to synergic effect of HTTA, the ternary-complex is formed on the electrode surface. Using cathodic stripping voltammetry, preelectrolysis is carried out at 0.0V (vs. Ag/AgCl) for 5 min, and followed by scanning till - 1.20 V (vs. Ag/AgCl), and the cathodic voltammograms show a highly sensitive peak of reduction current at about -0.9 V (vs. Ag/AgCl). The detection limit of uranyl ion is 1 x 10-10 mol/L for 5 min of preelectrolysis. The peak high is linearly related to the concentration of uranyl ion in the range of 6 x 10 -10 - 1.5 x 10-8 mol/L. The trace uranyl ion in Yangtze River is determined by TOPO modified electrode with the recovery of 94.8 - 108.0%