铜(Ⅱ)-茜素红S络合物在碳糊电极上吸附伏安法测定铜

Adsorptive Voltammetric Determination of Copper by the Reaction of Cu(Ⅱ)-ARS Complex at Carbon Paste Electrode

基于铜(Ⅱ)-茜素红S络合物在碳糊电极上的还原波,提出了吸附伏安法测定痕量铜的方法。在极谱分析仪上采用二次导数线性扫描伏安法进行分析,在含有1.0×10^(-5)mol·L^(-1)茜素红S的pH 4.0的乙酸-乙酸钠缓冲介质中,当富集电位为0 mV,富集时间为180 s,扫描速率为100 mV·s^(-1)时,铜(Ⅱ)-茜素红S络合物吸附在碳糊电极表面,于—316 mV(vs.SCE)处产生一灵敏的还原峰,络合物的峰电流与铜(Ⅱ)的浓度在1.0×10^(-9)～2.0×10^(-7)mol·L^(-1)范围内呈线性关系,检出限(3S/N)为6.0×10^(-10)mol·L^(-1)。方法用于锌合金中铜的测定,测定值的相对标准偏差(n=7)均小于3.5%。用标准加入法进行了回收试验,测得回收率在96.0%～102.0%之间。

In an acetate buffer of pH 4. 0, a complex of Cu（ Ⅱ ）-ARS was formed through the reaction of Cu（ Ⅱ ） ion with alizarin red S （ARS in short） with its concentration of 1. 0×10-5 mol· L-1. The adsorptive voltammetric behavior of the Cu（ I1 ）-ARS complex at the carbon paste electrode was studied under the conditions of accumulation at the potential of 0 mV for 180 s and of rate of scanning at 100 mV·s-1 , a sensitive reduction peak was observed at --316 mV （vs. SCE） due to adsorption and stripping of the copper complex on and from the surface of the electrode. Linear relationship between values of 2nd derivatives of the stripping peak current and concentration of Cu（ lI ） ion was kept in the range of 1.0× 10-9 --2. 0×10-7mol· L^-1. Detection limit （3S/N） found for the method was 6.0×10^-10mol· L^-1. The proposed method was applied to the determination of copper contents in samples of zinc alloys, giving values of RSD＇s （n=7） less than 3. 5%. Recovery of the method was tested by standard addition method, and values of recovery found were in the range from 96. 0%- 102. 0%.