镍(Ⅱ)-5-[2-(硝基吡啶偶氮)]-2,4-二甲氨基甲苯络合物在pH 7.0的克拉克(Clark-lubs)缓冲液中有较灵敏的极谱波,其峰电位Ep为-720 mV(vs.SCE),镍浓度在0.01-2.5 μg·L-1范围内与峰电流I′p呈线性关系,检出限为7.8 ng·L-1.经多种电化学方法证明该波为络合物吸附波,其电极过程为不可逆过程,电子转移数为2.试验了多种离子对峰电流I′p的影响,所拟方法已用于铝合金中镍的测定.

In a Clark-Lubs buffer medium of pH 7.0,a coordination complex was formed between Ni(Ⅱ) ion and 5-(5′-nitro-2′-pyridylazo)-2,4-dimethylamino toluene,and a sensitive adsorptive polarographic wave produced by this complex was observed with its peak potential (Ep) at -720 mV (vs.SCE).Linear relationship between the peak current (Ip) and the concentration of Ni was obtained in the range of 0.01-2.5 μg of Ni(Ⅱ) per liter of the solution,with a detection limit of 7.8 ng·L-1.It was proved by several electrochemical methods,that the polarographic wave is a complex-adsorptive wave,and the electrode process is a irreversible process,involving an electron-transfer number of 2.Interference tests of more than 20 anions and cations commonly co-existed were performed and selectivity of the proposed method evaluated.The method has been applied to the analysis of aluminum alloy.