ADSORPTIVE STRIPPING VOLTAMMETRIC BEHAVIOR OF GOLD(III) AT A HANGING MERCURY DROP ELECTRODE IN THE PRESENCE OF 1-(2'-PYRIDYLAZO)-2-NAPHTHOL

The stripping voltammetric determination of gold(III) based on the ads orptive accumulation of the Au(III)-1-(2'-pyridylazo)-2-naphthol compl ex on a hanging mercury drop electrode is reported. The reduction curr ent of the adsorbed gold complex ions is measured by differential-puls e 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 pre sence of ethanol-water (30%, v/v) and 0.5 M sodium sulphate are discus sed. A linear response up to 5.0 x 10(-8) M and a relative standard de viation of 2.9% at 3.0 x 10(-8) M were obtained. The UV-visible spectr um of the complex formed was also measured. The applicability of the m ethod 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.