In this current project, we report the most sensitive scheme for the measurement of maleic hydrazide by a modified differential pulse voltammetry (DPV) which is composed of a conventional DPV followed with a cleansing pulse train. The absorbed oxidized species (1,2-pyridazine-3,6-dione) on the solid electrode surface cause subsequent mass transfer hindrance which can be removed easily by a cleansing pulse train of a0.1 volts, 50 Hz for 5 minutes at the end of each voltammetric run. This scheme possesses the advantage of high sensitivity (submicro-molar range), which may be used in sensitive maleic hydrazide measurement or toxicity studies. This scheme offers a better tool to study a very low concentration of maleic hydrazide. A slope of 59.2 mV per decades from the potential versus pH plot was obtained. This result indicates that these are two electrons and two protons oxidation processes. The linear range of the calibration plot is up to 50 mM with a correlation coefficient of 0.9999. The sensitivity of the linear portion of the calibration plot yields a slope of 13.63 nA/mM with a detection limit of 20 nM (S/N = 3). The width of half peak width is 100 mV at the injection of 22 mM maleic hydrazide. Precision study possesses a relative standard deviation of 4.1% (n = 20).
Journal of the Chinese Chemical Society=中國化學會會誌 46(6), pp.879-884