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

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 1.0×10-5mol·L-1.The adsorptive voltammetric behavior of the Cu(Ⅱ)-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(Ⅱ) 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%.