Cathodic stripping voltammetric determination of tellurium(IV) in chloride media using a Tosflex/8-quinolinol mercury film electrode

A Tosflex/8-quinolinol (oxine) coated mercury film electrode (TOMFE) was developed for the determination of tellurium(IV) by square-wave cathodic voltammetry. The electrode is prepared by spin-coating a Tosflex/oxine solution onto the glassy carbon electrode surface. Subsequently, mercury is plated onto the electrode surface. Tellurium(IV) is preconcentrated, as TeCl^2-₆ in the chloride medium, onto the modified electrode by the ion-exchange effect of the Tosflex and the chelating effect of oxine. Good sensitivity was achieved through the catalytic process between oxine and tellurium. In comparison with the conventional mercury electrode, the TOMFE showed improved resistance to interferences from surface-active compounds on the determination of tellurium(IV). The interferences from metal ions, such as cadmium(II) and molybdenum(VI), which are capable of forming complexes with oxine were effectively eliminated by the addition of ethylenediamrnetetraacetate (EDTA) in the sample solution. The TOMFE is easy to prepare and chemically more stable than other anion-exchange polymer modified electrodes such as polyvinylpyridine modified mercury film electrode.