Determination of trace amounts of copper in iron and steel by differential pulse anodic stripping voltammetry at a glassy carbon electrode

Differential pulse anodic stripping voltammetry with a rotating glassy carbon-disk electrode in an acidic solution without any separation of the matrix is described for the determination of copper at the mu g g(-1) level in iron and steel. The interference of iron(III) was eliminated by reducing it with L(+)-ascorbic acid to iron(II). The calibration curves were linear over a concentration range of 1.6 x 10(-8) to 3.2 x 10(-5) M of copper with pre-electrolysis times of 1200 to 5 s and passed through the origin (correlation coefficients > 0.9992). The detection limit (3 sigma) was 0.78 ng ml(-1) for a pre-electrolysis time of 1200 s. The possible interferences were evaluated. Compared with the present JIS methods, the developed method has been successfully applied to the determination of 0.5 to 1000 mu g g(-1) of copper in iron and steel without any troublesome preconcentration steps using harmful chemicals. The relative standard deviations were approximately 0.9% at the 10 mu g g(-1) level. The time required for an analysis was within 50 min.