the number of electrons; is the Faraday constant; is the area of the planar electrode in cm2; is the initial concentration of the analyte in mol/cm3; is the diffusion coefficient for species in cm2/s; is the time in seconds. Under controlled-diffusion circumstances, the current-time plot reflects the concentration gradient of the solution near the electrode surface. The current is directly proportional to the concentration at the electrode surface. In 1922, Jaroslav Heyrovský reiterated the chronoamperometric method when he invented the polarographic method. It can use the basic circuit of the polarograph. To connect the fast recorder or oscilloscope, the dropping mercury electrode is not used, instead, the static electrodes such as suspended mercury, mercury poll or platinum, gold and graphite are used. In addition, the solution is not stirred. In the presence of the inert electrolytes, the mass transfer process is mainly diffusion. Jarroslav Herovsky derived the chronopotentiometric method from the Cottrell equation. Chronopotentiometry is an electrochemical method that can generate a stable current that can flow between two different electrodes. Application Controlled-potential (bulk) electrolysis One of the application of chronoamperometry is controlled-potential (bulk) electrolysis, which is also known as potentiostatic coulometry. During this process, a constant potential is applied to the working electrode and current is monitored over time. The analyte in one oxidation state will be oxidized or reduced to another oxidation state. The current will decrease to the base line (approaching zero) as the analyte is consumed. This process shows the total charge (in coulomb) that flows in the reaction. Total charge (n value) is calculated by integration of area under the current plot and the application of the Faraday's law. The cell for controlled-potential (bulk) electrolysis is usually a two-compartment (divided) cell, contained a carbon rod auxiliary anode and is separated from the cathode compartment by a coarse glass frit and methyl cellulose solvent electrolyte plug. The reason for the two compartment cell is to separate cathodic and anodic reaction. The working electrode for bulk electrolysis could be a RVC disk, which has larger surface area to increase the rate of the reaction. Controlled-potential electrolysis is normally utilized with cyclic voltammetry. Cyclic voltammetry is capable to analyse the electrochemical behavior of the analyte or the reaction. For instance, cyclic voltammetry could tell us the cathodic potential of an analyte. Since the cathodic potential of this analyte is obtained, controlled-potential electrolysis could hold this constant potential for