Oxidative amperometric flow injection determination of oxalate at an electrochemically pre-treated glassy carbon electrode

An effective electrochemical pre-treatment of a newly polished glassy carbon electrode has been shown to be essential if sensitive and reproducible signals are to be obtained in the oxidative determination of oxalate. Pre-treatment at + 1.75 V for 10 min and then at –1.0 V for 1 min in the 0.05 M phosphate buffer (pH 7.0) used as an eluent for the determination was shown to be effective in producing a well shaped hydrodynamic voltammogram, maximum signal size and improved precision at the measurement potential used (1.5 V). Calibration graphs were rectilinear for up to 100 µg ml–1 of oxalic acid dihydrate.