稀土化学修饰电极的研究——铕(Ⅲ)的电化学行为

Rare Earth Chemically Modified Electrode——Electrochemical Behaviour of Europium(Ⅲ)

本文研究了铕(Ⅲ)在Nafion聚合物薄膜化学修饰电极上的电化学行为。研究结果表明,在pH5.8的醋酸缓冲溶液中,铕(Ⅲ)的氧化还原非常接近可逆过程。利用二甲酚橙的络合作用和Nafion的阳离子交换作用,在选定条件下,铕(Ⅲ)的导数波高度与其浓度在2.0×10^(-7)～1.0×10^(-5)mol/L范围内成线性关系,检出限为1.0×10^(-7)mol/L。当富集时间为10min时,检出限可达2.0×10^(-8)mol/L,Sm(Ⅲ)、Yb(Ⅲ)及其他稀土元素基本不干扰,可用于铕(Ⅲ)的分析测定。同时避免了使用汞(Ⅱ)的问题。

Electrochemical behaviour of Eu(Ⅲ) at a Nafion polymer film electrode was studied by using cyclic voltammetry. The result showed that the electrochemical reaction of Eu(Ⅲ) in acetic buffer solution (pH 5.8) at a Nafion film electrode is nearly a reversible process. A sensitive stripping voltammetry method for the determination of Eu(Ⅲ) was proposed in the presence of xylenol orange (XO) as a ligand at the Nafion film electrode. In the solution of 0.1mol/L HAc-NaAc (pH2.9) containning 1.0×10^(-4)mol/L of XO, cathodic scanning from -0.2 to -1.5V, (vs. SCE) at sweep rate of 200mV/s after 1 min at-0.2V, the reduction wave of Eu(Ⅲ)-XO at about -1.2V was recorded, The peak current is proportional to the concentration of Eu(Ⅲ) in the range of 2.0×10^(-7)～1.0×10^(-5) mol/L with a detection limit of 1.0×10^(-7)mol/L. When the accumulated time at -0.2 V was increased to 10min, the detection limit was below 2.0×10^(-8) mol/L. No interferences of Sm(Ⅲ), Yb(Ⅲ) and other rare earth ions were observed. And the mercury pollution in the method could be avoided.