Studies On The Adsorptive Voltammetry Of Gallium(Ⅲ),Zirconium(Ⅳ) And Copper(Ⅱ) Complexes At Carbon Paste Electrode

Several new methods were proposed, to determine metal ions on the basis of the reduction or oxidization of ligand bonded in complexes at carbon paste electrode. The adsorptive voltammetric behavior of the complexes of Ga(III)-ARS, Zr(IV)-ARS and Cu(II)-ARS at carbon paste electrode were studied in detail.There are three parts in this paper.In the first part, the adsorptive voltammetric behavior of Ga(III)-ARS complex at a carbon paste electrode in cathodic and anodic potential area were studied in detail. The electrode processes mechanism and the properties of the complex have been investigated. Cathodic adsorptive voltammetry of the system is more sensitive than anodic adsorptive voltammetry and it was used for the determination of trace gallium in food samples successfully. It also was compared with the cathodic voltammetric behavior at a mercury electrode. The cause of the difference between the behavior at two kinds of electrodes was discussed primarily.In the second part, the anodic adsorptive voltammetric behavior of Zr(IV)-ARS at a carbon paste electrode was studied. There was a sensitive anodic adsorptive peak at 690mV produced by the oxidization of ARS bonded in the complex. The height of the second-order derivative peak was proportional to the concentration of Zr(IV) over the range of 1.0$l0-9-2.0$10-7 mol/L, and the detection limit is 5.0$10-10 mol/L with accumulation time of 2min. The electrode processes mechanism and properties of the complex were studied. The method was applied to determine trace zirconium in ore samples with satisfactory results.In the third part, a new method for the determination of copper onthe basis of the oxidization of ARS bonded in Cu(II)-ARS complex at a carbon paste electrode was proposed. It provided a new way to determine electro-active metal ions. The peak potential for the complex is at 590mV, the height of the second-order derivative peak is proportional to the concentration of copper(II) over the range of 2.0$l-9-4.0$l0-7 mol/L, and the detection limit is found to be 8.0$l0-10mol/L with the accumulation time of 90s. The electrode processes mechanism and the properties of the complex have been investigated. The method was applied to the determination of trace copper in Chinese herbs samples with satisfactory results.In a word, we have established several new methods for the determination of Ga(III), Zr(IV) and Cu(II). These systems have high sensitivity and excellent selectivity, which make them full of practical and theoretical value.