Polarographic and voltammetric study of the Sc(III)-acid chrome blue K complex and determination of trace scandium

A new system using a polarographic adsorptive wave for determining trace scandium was proposed. In 0.2 mol/L NH4OAc, the Sc(III)-ACBK [1,8-dihydroxy-2-(2-hydroxy-5-sulfo-1-phenylazo)-3,6-disulfo-naphthalene, called acid chrome blue K] complex emerged a sensitive adsorptive complex wave (Ep' = -0.67V). The molar ratio of Sc(III) to ACBK in the complex was established as 1:2 and the apparent stability constant β2 = 2.7 x 1015. But for Y(III), the molar ratio was 1:1 and β=1.5 x 105. Because of the particularity of Sc complex, the sensitivity and the selectivity of determination Sc is much better than that of other rare earth ions. The detection limits is 1.1 x 10-7 mol/L for oscillopolarography and 2.0 x 10-8 mol/L for adsorptive stripping voltammetry