Electrocatalysis and determination of hydrazine compounds in liquid chromatography at a mixed-valent cobalt oxide/cyanocobaltate film electrode

Abstract A glassy carbon electrode coated with an electrodeposited film of mixed-valent cobalt oxide/cyanocobaltate (CoO/CNCo) enabled hydrazine compounds to be catalytically oxidized at the greatly reduced overpotential and in a wide operational pH range (pH 2.0–7.0). Electrocatalytic activity at the CoO/CNCo modified electrode was evaluated with respect to solution pH, film thickness, supporting electrolyte ions, potential scan rate, operating potential, concentration dependence and other variables. The CoO/CNCo film electrode was completely compatible with a conventional reversed-phase liquid chromatographic (RP-LC) system. Practical RP-LC amperometric detection (RP-LCEC) of hydrazines was performed. A dynamic linear response range over three orders of magnitude and a detection limit at the pmol level were readily obtained. The CoO/CNCO film electrode exhibited excellent electrocatalytic stability in the flowing streams.