Amperometric sensors for simultaneous superoxide and hydrogen peroxide detection

A two-channel sensor capable of almost instantaneous simultaneous detection of superoxide radical and hydrogen peroxide in the concentration range 10(-7)-10(-4) M is very important for understanding of a number of rapid kinetics processes, A glassy carbon working microelectrode covered by an electrodeposited polypyrrole/horseradish peroxidase (PPy/HRP) membrane was employed as a H2O2 sensor. Another glassy carbon microelectrode covered by a composite membrane of an inside layer of PPy/HRP and an outside layer of superoxide dismutase was employed as a working electrode for superoxide detection. These two working electrodes with Pt counter and tungsten oxide (WO3) reference electrodes were contained in one 6 nam diameter Teflon cylinder, Simultaneous measurements were performed at a potential of -60 mV (vs WO3 reference, pH 5.1). Additional sensor characterization was performed for pH 5.1-9.0. Superoxide sensor behavior as a function of membrane deposition conditions and coating time is reported. Sensors' mutual influence, selectivity, response times, linearity, stability, and sensitivity for hydrogen peroxide and superoxide are presented and discussed, A mathematical model of sensors' response is proposed, with model calculation corresponding to experiment within 10%.