Abstract: Flow injection biamperometry was extended to irreversible couple systems. For the biamperometry, the essential condition is the coexistence of two reactants, with opposite electrode reaction, of two independent and irreversible couples in the same system. The system can be skillfully constructed with analyte by choosing such a reactant of one couple as its standard redox potential which was better closed to that of the analyte as nearly as possible. In the chosen system, provided the real potentials of the two working electrodes have exceeded the deposition potential of two reactants by imposing a suitable potential difference ΔEbetween these two electrodes, faradic current i will flow through circuit. When the concentration of the chosen reactant remains larger constant, the circuit current i will be linearly proportional to the analyte of interest over certain concentration range. To verify the feasibility of the biamperometry, three systems of the dissolved oxygen separately with ascorbic acid, hydrazine chloride and hydroxyamine 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 Δ E0.0 V, the circuit current i was linearly proportional to these three analytes in the concentration range of 1×10^-5 —1×10^-3 mol/Lfor ascorbic acid, 1×10^-6 —1×10^-4 mol/Lfor hydrazine chloride and hydroxyamine chloride, respectively.

Key words: Biamperometry, Flow injection analysis, Irreversible couple