Types of Current found in Polarography

There are many types of current met with in polarography. Most types of current are not analytically useful. Fortunately the most useful, the diffusion controlled current, is also very common. 

A number of different processes can be responsible for limiting the rise in current. In essence, electrolysis can only occur as rapidly as the electro-active species is made available to the electrode surface. For example when the rise is limited by the maximum rate at which the analyte can diffuse to the electrode, we speak of a diffusion- 

Since some types of current are more useful or more reproducible than others it is necessary always to identify the type of current involved. 

This is a general term for all currents caused by electrolysis of chemical species in the solution. It is so-called because electrolysis obeys Faraday s law. The term is used to differentiate electrolysis currents from currents, such as capacitive current, in which the cell is acting as an electronic component. Diffusion current, kinetic current etc are all types of faradaic current. 

This is the only generally useful type of current from an analytical viewpoint. While other types of current occasionally find analytical application, diffusion current is generally the most reproducible type of current. 

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