Adsorptive Stripping Determination of Scandium(III) with Mordant Blue 9 on Silver Amalgam Film Electrode

A new adsorptive stripping voltammetric method for the determination of trace scandium(III) based on the adsorption of scandium(III)-mordant blue 9 complex on the cyclic renewable mercury film silver based electrode (HQ(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2 nM (0.09 mu gL(-1)) to 90 nM (4 mu g L-1) for a preconcentration time of 45 s, with correlation coefficient of 0.9995. For a Hg(Ag)FE with a surface area of 7.9 mm(2) the detection limit for a preconcentration time of 90 s is as low as 5 ng L. The repeatability of the method at a concentration level of the analyte as low as 0.2 mu g L-1, expressed as RSD is 1.9% (n=5). The proposed method was successfully applied and validated by studying the certified reference material (CRM 320 - river sediment) and natural samples with simultaneous recovery of Sc(III) from spiked water and sediment samples.