镍(Ⅱ)-偶氮氯瞵Ⅰ-硫脲体系极谱络合吸附波的研究

Study on polarographic complex adsorption wave of nickel(Ⅱ)-chlorophosphonazo Ⅰ-thiourea system

镍（Ⅱ）与偶氮氯瞵Ⅰ形成摩尔比为1：2的络合物在0．4mol／L氨水-醋酸铵（pH8．2）缓冲溶液中有一灵敏的极谱波，其峰电位在-0．63V（vs．SCE），加入硫脲对峰高有增敏作用，镍质量浓度在0．002～2．00mg／L范围内与峰电流Ip＂有良好的线性关系（r=0．9989），方法检出限为0．001mg／L。通过对极谱波性质的研究表明，该波为络合物吸附波，其电极过程不可逆，电子转移数为2。所拟方法用于铝合金中微量镍（Ⅱ）的测定，相对标准偏差小于5％，回收率为96％～104%。

Nickel（Ⅱ） could form a 1 ： 2 complex with chlorophosphonazo a which showed a sensitive polarographic wave in 0.4 mol/L ammonia-ammonium acetate buffer solution at pH 8.2. The peak potential was at -0.63 V （vs. SCE）. Thiourea had sensitivity enhancing effect on the absorption peak. The mass concentration of nickel in the range of 0. 002-2.00 mg/L showed good linearity with peak current （ip＂）, with correlation coefficient of r = 0. 998 9. The detection limit of method was 0. 001 mg/L. The studies on the properties of polarographic wave indicated that this wave was complex adsorption wave, and the electrode process was irreversible with electron transfer number of 2. The proposed method was applied to the determination of micro nickel （Ⅱ）, and the relative standard deviation （RSD） was less than 5 %, and the recovery of standard addition was 96%-104%.