Catalytic oxidation and flow detection of hydrazine compounds at a nafion/ruthenium(III) chemically modified electrode

Cyclic voltammetry was used to investigate the electrochemical behaviour of a nafion/ruthenium(III) modified glassy carbon towards the electrooxidation of hydrazine compounds in perchloric acid solutions. Flow injection experiments were performed to characterize the electrode as an amperometric sensor for the determination of hydrazine compounds. The effects of several common interferents on the amperometric signal were measured. The electrode response was stable: over 30 h only a 6% signal loss was observed. The 3σ limit of detection (LOD) was 1×10−7 M, corresponding to 0.65 ng of injected hydrazine sulfate (i.e. 3.2 μg l−1 hydrazine). The detector response was linearly dependent on the concentrations of hydrazine compounds over three orders of magnitude above the LOD. Examples of the determination of hydrazine added to drinking water and river water are reported. Good levels of recovery (95–101%) were obtained at the 1–13 μM level.