Flow injection biamperometry for irreversible couple systems

Flow injection biamperometry was extended to irreversible couple systems. F or the biamperometry, the essential condition is the coexistence of two rea ctants, with opposite electrode reaction, of two independent and irreversib le couples in the same system. The system can be skillfully constructed wit h analyte by choosing such a reactant of one couple as its standard redox p otential which was better closed to that of the analyte as nearly as possib le, In the chosen system, provided the real potentials of the two working e lectrodes have exceeded the deposition potential of two reactants by imposi ng a suitable potential difference Delta E between these two electrodes, fa radic current i will flow through circuit. When the concentration of the ch osen reactant remains larger constant, the circuit current i will be linear ly proportional to the analyte of interest over certain concentration range . To verify the feasibility of the biamperometry, three systems of the diss olved oxygen separately with ascorbic acid, hydrazine chloride and hydroxya mine chloride were examed, In phosphate buffer(pH 6, 9) solution containing the dissolved oxygen, using two activated platinum wire working electrodes imposed by potential difference Delta E 0. 0 V, the circuit current i was linearly proportional to these three analytes in the concentration range of 1 X 10(-5)-1 X 10(-3) mol/L for ascorbic acid, 1 X 10(-6)-1 X 10(-4) mol/L for hydrazine chloride and hydroxyamine chloride, respectively.