VOLTAMMETRIC AND POTENTIOMETRIC DETERMINATION OF GOLD IN GOLD-PLATED ELECTROTECHNICAL COMPONENTS

Differential pulse voltammetry was used to determine gold in gold-plated electrotechnical components. Samples were dissolved to form tetrachloroaurate, which was determined on a carbon paste electrode containing tricresyl phosphate as pasting liquid. A characteristic cathodic peak for tetrachloroaurate, whose selective accumulation is based on extraction, is obtained during cathodic scan from +0.8 to -0.5 V vs Ag/AgCl electrode. The accompanying Fe(III) and Cu(II) ions from the matrix are masked by adding EDTA. Gold can be determined in the presence of their thousand-fold excess in the concentration range 1 . 10(-5) - 1 . 10(-7) mol l-1. The results were confirmed by potentiometric titration with a solution of 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex) by using a coated-wire indicator electrode with a softened plastic membrane.