POLAROGRAPHIC BEHAVIOUR OF CHROMIUM(6) COMPOUNDS AT DME . MEDIUM EFFECT ON NATURE OF WAVES

The polarographic behaviour at the dme of chromate and dichromate is investigated within the concentration limits 0·2 - 2·0 mM. In acid solutions, 2 waves are observed representing the reduction to Cr(III) and Cr(II). In neutral unbuffered solutions, 4 waves are obtained for chromate, whereas dichromate gives 5 waves. In NaOH, 3 or 1 waves are observed at lower and higher alkalinities respectively. In buffer solutions, the shape of the polarograms depends essentially on the pH. The nature of the waves is discussed. Some media were found to be suitable for the polarographic determination of Cr(VI). © 1968.