三辛基氧化膦修饰电极三元络合物体系测定痕量铀的研究

DETERMINATION OF TRACE URANIUM IN TERNARYCOMPLEX SYSTEM WITH TRI-N-OCTYLPHOSPHINE OXIDE MODIFIED ELECTRODE

本文用玻碳电极为基体制成三辛基氧化膦(TOPO)修饰电极,研究了在噻吩甲酰三氟丙酮(HTTA)存在的HAc-NaAc体系中,UO_2^(2+)离子在电极上形成三元络合物,并用阴极溶出伏安法测定了痕量UO_2^(2+)离子。在6.0×10^(-10)～1.5×10^(-8)mol/L UO_2^(2+)的浓度范围内与溶出峰高呈良好的线性关系,检出限为1.0×10^(-10)mol/L。

The preparation of tri-n-octylphosphine oxide (TOPO) modified electrode and electrochemical 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 synegic 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 5min, and followed by scanning till-1.20V (vs.Ag/AgCl), and the cathodic voltammograms show a highly sensitive peak of reduction current at about -0.9V (vs.Ag/AgCl). The detection limit of uranyl ion is 1×10^(-10) mol/L for 5 min of preelectrolysis. The peak height is linearly related to the concentration of uranyl ion in the range of 6×10^(-10)-1.5×10^(-8) mol/L. The trace uranyl ion in Yangtze River is determined by TOPO modified electrode with the recovery of 94.8—108.0％.