Cathodic stripping voltammetric determination of tellurium(IV) at a Nafion/8-quinolinol mercury film modified electrode

A Nafion/8-quinolinol (oxine) coated mercury film chemically modified (NOMF) electrode for the determination of tellurium(IV) is described. The electrode is prepared by spin-coating a solution of the mixed Nafion/oxine onto the electrode surface. Subsequently, mercury is plated onto the electrode surface. Tellurium(IV) was preconcentrated onto the NOMF electrode from the sample solution containing 0.01 M ethylenediaminetetraacetate (EDTA), and determined by square-wave cathodic stripping voltammetry. This modified electrode showed improved resistance to interferences from surface-active compounds on the determination of tellurium(IV), especially for sodium dodecyl sulphate which is generally considered as a major interferent in the determination of tellurium(IV) at a hanging-mercury drop electrode. The addition of EDTA effectively eliminated the interferences from metal ions, such as molybdenum(VI) and lead(II), which are capable of forming complexes with oxine. Linear calibration graphs were obtained over the range 1-80 μg 1^-1 of tellurium(IV), with a detection limit (3 × blank signal) of 0.2μg/l.