基于双波测量的催化动力学极诸法测定钒

Catalytic Kinetic-Polarographic Determination of Trace Vanadium Based on Oxidation of Thoron by Potassium Bromate

在 ｐＨ ４．５ ＨＡｃ－ＮａＡｃ缓冲溶液中，钍试剂分别于－ ０．３６ Ｖ、－ ０．６０ Ｖ产生两个灵敏的极谱波。基于钒对溴酸钾氧化钍试剂的催化作用，建立了双极谱波测量的催化动力学极谱法。钒浓度在０．７～１５μｇ／Ｌ与△Ｉ（△Ｉ１＋ Ｉ２）呈线性关系，检测限为０．５μｇ／Ｌ。研究了极谱波性质及电极反应机理。本法简便、灵敏、准确，已用于直接测定水中痕量钒。

In HAc-NaAc buffer solution (pH 4. 5), Thoron produces two reduction wave peaks at - 0.36 V and - 0.60 V(vs. SCE). A new kinetic polarographic method for the determination of trace vanadium is proposed. The method is based on the reaction of vanadium(V) catalyzed oxidation of thoron by potassium bromate. The reaction is monitored by measuring the wave-hight decrease both at - 0 .36 V and - 0. 60 V. △I(△I1 + △I2 ) is linearly proportional to vanadium concentration in the range of 0.7 - 15 μg/L. The detection limit is 0.5 μg/L. The polarographic behaviour and electrode process have been studied. The method is sensitive, accurate and simple, it has been applied to the determination of trace vanadium in water samples.