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制备了镉修饰铂电极,用循环伏安法表征了Cd(Ⅱ)在该电极上的吸附特性,探讨了电极的响应机理.通过优化试验条件,建立了一种新的测定Cd(Ⅱ)的示波双电位滴定法.在1.0 mol/L的六次甲基四胺溶液中(pH=6.0),用制备的修饰铂电极作为双指示电极,以EDTA标准溶液滴定Cd(Ⅱ),利用示波器屏幕上荧光点的显著最大位移指示滴定终点.Cd(Ⅱ)在9.0×10-4～3.5×10-3mol/L时,回收率为99.8%～100.3%.该修饰电极具有良好的稳定性和重现性,在含有1.0×10-3mol/L Cd(Ⅱ)的溶液中,连续13次测定,所得终点电位值均在37 mV左右,其相对标准偏差(RSD)0.02%.应用该方法测定含镉样品,RSD值(n=7)小于0.81%,回收率为99.71%～100.09%,测定结果与指示剂法测定值相符.
The Cd electrode modified by platinum was prepared and the adsorption characteristics of Cd (Ⅱ) on the electrode were characterized by cyclic voltammetry. The response mechanism of the electrode was discussed. By optimizing the experimental conditions, a new Cd (Ⅱ) Oscillopotentiometric titration of Cd (Ⅱ) in 1.0 mol / L hexamethylenetetramine solution (pH = 6.0) was carried out using the prepared modified Pt electrode as the dual indicator electrode and the titration of Cd (Ⅱ) The significant maximum displacement of the fluorescent spot on the screen indicates the end point of the titration.The recovery of Cd (Ⅱ) was 99.8% -100.3% at 9.0 × 10-4 ~ 3.5 × 10-3 mol / L.The modified electrode had good stability and Reproducibility, and the final endpoint potentials were all around 37 mV with a relative standard deviation (RSD) of 0.02% in a solution containing 1.0 × 10-3 mol / L Cd (Ⅱ) for 13 consecutive determinations The RSD value (n = 7) was less than 0.81% and the recovery rate was 99.71% ~ 100.09%. The determination results were consistent with those of indicator method.