Trace determination of zirconium by adsorptive anodic stripping voltammetry of its complex with alizarin violet using a glassy carbon electrode modified with acetylene black-dihexadecyl hydrogen phosphate composite film

We report on a novel electrochemical method for the sensitive determination of trace zirconium (Zr) at a glassy carbon electrode modified with a film of acetylene black containing dihexadecyl hydrogen phosphate and in the presence of alizarin violet (AV). The method is based on the preconcentration of the Zr(IV)-AV complex at a potential of -200 mV (vs. SCE). The adsorbed complex is then oxidized, producing a response with a peak potential of 526 mV. Compared to the poor electrochemical signal at the unmodified GCE, the electrochemical response of Zr(IV)-AV complex is greatly improved, as confirmed by the significant increase in peak current. The effects of experimental conditions on the oxidation current were studied and a calibration plot established. The oxidation current is linearly related to the Zr(IV) concentration in the 8.0 pM to 10 nM concentration range (c(AV) = 0.2 mu M) and 10 nM similar to 0.6 mu M (c(AV) = 2.0 mu M), and the detection limit (S/N = 3) is as low as 4.0 pM for a 3-min accumulation time. The method was successfully employed to the determination of zirconium in standard ore samples.