Carbon fibre microelectrodes modified with rhodium for the electrocatalytic determination of hydrazine Original Research Article

The electroanalytical capabilities of cylindrical carbon fibre microelectrodes (CFMEs) modified with electrodeposited rhodium for their use as amperometric microsensors in the detection of hydrazine under flow-injection conditions are discussed. Metallized CFMEs were prepared potentiostatically at −0.80 V in an acetate buffer solution of pH 4.5 containing 100 mg l−1 Rh(III), and characterised by cyclic voltammetry. Rh-CFMEs showed electrocatalytic ability towards the oxidation of hydrazine and some other organic compounds. A good stability of the metallised microelectrodes was found when they were used for the amperometric detection of hydrazine under flowing conditions, with no need to regenerate the electrode surface. Moreover, the signal-to-noise ratio was remarkably better at the Rh-CFME than at a Rh-modified glassy carbon electrode of conventional size. A limit of detection of 6.2×10−7 mol l−1 hydrazine (approximately 20 μg l−1) was obtained. The effect of the presence of potential interferents was studied and the flow-injection method was applied to the determination of hydrazine in boiler water samples spiked with 0.64 mg l−1 analyte.