Effect of Complexing Agents:

Half-wave Potential, E_1/2

The electro-active material in polarography is characterized by its half-wave potential, E_1/2.  Under any defined set of experimental conditions, each substance has its own characteristic E_1/2 and this is the basis of qualitative polarographic analysis. The half- wave potential is defined as the potential at which the current due to the reduction or oxidation of the substance responsible for the wave is half as large as on the plateau.

A half-wave potential is also independent of the electrode characteristics and concentration of the electroactive substance, therefore serves for the qualitative identification of an unknown substance.