Sensitive amperometric determination of chemical oxygen demand using Ti/Sb-SnO2/PbO2 composite electrode

A novel Ti/Sb-SnO₂/PbO₂ composite electrode was fabricated for COD determination. The new electrode configuration improved the sensitivity of the amperometric method apparently. Effects of common experimental parameters, such as applied potential, pH and concentration of the electrolyte on its analytical performance were investigated. A linear range of 0.5-200 mg L⁻¹ COD and a detection limit (a signal-to-noise ratio of 3) of 0.3 mg L⁻¹ were achieved under optimized conditions. The experiments for detecting COD in model samples and real samples were carried out to evaluate the electrode's performance. The obtained results were in good agreement with those determined by the standard dichromate method, with a relative error less than 12%.