镍(Ⅱ)—组氨酸体系络合吸附波

Polarographic Adsorptive Wave of Nickel(Ⅱ)-Histidine Complex

以0.1mol/L NH_3-0.1mol/L NH_4Cl为支持电解质,镍(Ⅱ)-组氨酸络合物在示波极谱仪上产生灵敏的还原波。峰电位-1.25V(vs.SCE)。峰电流与镍的浓度在5.0×10^(-8)～1.0×10^(-5)mol/L呈线性关系。应用循环伏安法等多种电化学实验手段判明该极谱波为络合吸附波。

The polarographic behaviour of nickel (Ⅱ)-histidine system was investigated. The histidine leads to an enhancement of the cathodic peak current of nickel (Ⅱ) in the single sweep polaragraph, with a peak potential of -1.25V (vs.SCE). When the concentration of histidine is proper, the peak current is proportional to the concentration of nickel (Ⅱ) over the range of 5.0×1(10^(-8)~1.0×10^(-5)mol/L. The charateristic of the polarographic wave were studied using cyclic voltammetry, normal pulse polarography and other methods. The results indicate that the polarographic wave is an adsorptive wave of compex with reactant weakly adsorbed. The adsorptive wave is probably caused by the adsorption of the complex of nickel (Ⅱ) and histidine Ni(is)_2, then by the reduction of Ni(is)_2to Ni(Hg).