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 elimin ated by reducing it with L(+)-ascorbic acid to iron(II). The calibrati on 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 det ection limit (3 sigma) was 0.78 ng ml(-1) for a pre-electrolysis time of 1200 s. The possible interferences were evaluated. Compared with th e present JIS methods, the developed method has been successfully appl ied to the determination of 0.5 to 1000 mu g g(-1) of copper in iron a nd 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.