Adsorptive Stripping Voltammetric Behaviour of Gold(III) at Hanging Mercury Drop Electrode in the Presence of 1-(2-pyridylazo)-2-naphthol

The stripping voltammetric determination of gold(III) based on the adsorptive accumulation of the Au(III)—1-(2′-pyridylazo)−2-naphthol complex on a hanging mercury drop electrode is reported. The reduction current of the adsorbed gold complex ions is measured by differential-pulse cathodic stripping voltammetry. The peak potential is at −0.8 V vs. Ag/AgCl. The effects of various parameters (pH, ligand concentration, accumulation potential and collection time) on the response in the presence of ethanol-water (30%, v/v) and 0.5 M sodium sulphate are discussed. A linear response up to 5.0×10^−8 M and a relative standard deviation of 2.9% at 3.0×10^−8 M were obtained. The UV-visible spectrum of the complex formed was also measured. The applicability of the method to the determination of gold(I) and mixtures of gold(I) and (III) compounds was also successfully carried out. Possible interferences by trace metals on the proposed method were examined.