Rapid determination of copper in steel by electrolytic dissolution/stripping voltammetry

A rapid and highly sensitive system has been developed for the determination of copper in steel by differential pulse anodic stripping voltammetry coupled with electrolytic dissolution of a solid sample. Disk-shaped steel samples were anodically dissolved at a constant current of 5 A (current density of ca. 1.6 A cm(-2)) for 30 s in 5 cm(3) of 6 mol dm(-3) hydrochloric acid with vigorous stirring, with 100% current efficiency. After the addition of 10 cm(3) of a 2 mol dm(-3) sodium hydroxide solution, copper(II) in the resulting solution was electrodeposited on a glassy carbon electrode at -0.8 V vs. Ag/AgCl for 60 s without any removal of the iron matrix; the deposit was then anodically stripped at a scan rate of 80 mV s(-1) to 0 V vs. Ag/AgCl in the same electrolysis cell. All measurement sequences were automatically controlled. The determination of 0.001 to 0.051 mass% of copper in steel was achieved with relative standard deviations below 5% within 120 s. The proposed analytical system is applicable not only to the rapid determination of 0.0003 to 0.26 mass% of copper in steel with electrodissolution times of 3 to 50 s, but to the multi-element determination of metallic elements in steel, and is suitable for controlling the steel making process and the product quality at production sites.