Cathodic Stripping Voltammetry of Tellurium(IV) at a Rotating Silver Disk Electrode

A simple and reproducible method is described for the determination of traces of tellurium(IV) based on differential pulse cathodic stripping voltammetry without the addition of any other metal ions to an acidic medium. Tellurium(IV) ions in a 0.18 mol dm-3 hydrochloric acid-0.20 mol dm-3 nitric acid solution (4 cm3) were electrodeposited on a rotating silver disk electrode (2000 rpm) as silver telluride at -0.45 V vs. Ag/AgCl for 30 min. A cathodic stripping voltammogram was then recorded in an another solution (2 mol dm-3 sodium hydroxide) at a scan rate of 50 mV s-1 to -1.5 V vs. Ag/AgCl. Only a single well-defined peak could be seen at -1.16 V vs. Ag/AgCl. The calibration curve was linear up to at least 300 ng cm-3 of tellurium(IV) (2.4×10-6 mol dm-3) and passed through the origin with an RSD of 6.8% for 50 ng cm-3 (n=5). The detection limit (3σ) was 0.62 ng cm-3. The possible interferences were evaluated.