The three main categories are potentiometry (the difference in electrode potentials is measured), amperometry (electric current is the analytical signal), coulometry (charge passed during a certain time is recorded).
[7] Amperometry indicates the whole of electrochemical techniques in which a current is measured as a function of an independent variable that is, typically, time (in a chronoamperometry) or electrode potential (in a voltammetry).
In a chronoamperometry, a sudden step in potential is applied at the working electrode and the current is measured as a function of time.
[8] Since this is not an exhaustive method, microelectrodes are used and the amount of time used to perform the experiments is usually very short, typically 20 ms to 1 s, as to not consume the analyte.
A voltammetry consists in applying a constant and/or varying potential at an electrode's surface and measuring the resulting current with a three-electrode system.
This method, in practical terms, is non-destructive since only a very small amount of the analyte is consumed at the two-dimensional surface of the working and auxiliary electrodes.