Determination of chromium(VI) and total chromium in water by in-electrode coulometric titration in a porous glassy carbon electrode

Chromium(VI) is determined through its direct electrochemical reduction in the bulk of a porous glassy carbon electrode. An electrode filled with the acidified sample and Cr(VI) is reduced by means of a constant current whereas the potential of the electrode is monitored. The limits of detection and quantification were found to be 1.9 and 6.0 mu g . L-1, resp. The linear range, repeatability and reproducibility were found to be 5 - 500 mu g . L-1, 1.2, and 1.8%, resp. The influence of Fe(III), Ca(II), Mg(II), sulphates, nitrates, humic acids and surfactants was investigated. Total chromium was measured after chemical oxidation of Cr(III) to chromate by permanganate. The method was applied to analyses of water samples.