AMPEROMETRIC DETERMINATION OF HYDROGEN-PEROXIDE WITH A MANGANESE DIOXIDE-MODIFIED CARBON-PASTE ELECTRODE USING FLOW-INJECTION ANALYSIS

A carbon paste electrode bulk modified with MnO2 was investigated as a n amperometric detector for hydrogen peroxide in flow injection analys is (FIA). With an operating potential of +0.46 V versus Ag/AgCl, H2O2 produces catalytic oxidation currents which can be exploited for quant itative determinations. Factors influencing the analytical performance of the electrode, such as paste composition and pH, were studied both for batch voltammetry and for FIA. For the flow system the influence of the injection volume and flow rate were examined. The amperometric signals are linearly proportional to H2O2 concentrations in the range 0.5-350 mg l(-1), showing a detection limit (three times the signal-to -noise ratio) of 45 mu g l(-1).