Voltammetry with disk electrodes and its analytical application: X. The voltammetry and electrochemical stripping analysis of gold in aqueous and nonaqueous media

Abstract

Cyclic voltammetry of AuCl 4 − was studied in the medium of aqueous hydrochloric acid and in non-aqueous media using the rotating disc electrode made from glassy carbon. Cyclic voltammetry in nonaqueous medium was carried out after the extraction of gold from the aqueous solution 4 M HNO 3 with 60% TBP in benzene. The reduction of gold in this medium takes place up to the potential at which the evolution of hydrogen starts. Gold was determined by stripping voltammetry down to the concentration 10 −7 to 5×10 −6 M and by stripping chronopotentiometry down to 3×10 −7−5×10 −6 M. The metals in the concentration 5×10 −3 M: In 3+, Fe 3+, Co 2+, Cd 2+, Mn 2+, Pb 2+, Zn 2+, Ag + and other metals which are not extracted by TBP do not interfere with the stripping chronopotentiometric determination of gold (10 −6 M) carried out under optimum conditions. The error of the determination did not exceed ±3%. The determination of gold with an error of ±5% can be carried out in the presence of 3.5×10 −4 M Bi 3+, 3×10 −4 M Sb 3+ and 2.5×10 −4 M Hg 2+. Pt 4+ interfered when its concentration was higher than the gold concentration. Pd 2+ did not interfere up to the concentration 3×10 −4 M.