Electrogravimetry:

It is the oldest of electroanalytical techniques and was well established by the end of nineteenth century. It includes the controlled potential reduction of a solution of a metal salt that is continued till the current falls near to zero. Therefore, electrolysis is used as a means of chemical transformation (reduction of the metal ion). The product of analysis (i.e., after electrolysis) is weighed as a deposit on one of the electrodes (working electrode). The increment within the weight of the previously weighed working electrode leads to the determination of the metal context of the sample solution. Since the reaction product after electrolysis is determined ordinarily by weighing, hence the name "electrogravimetry".

The method is very simple to apply in the analysis of a single element in the absence of any other substance which might be deposited. For this analytical method the appropriate electrode potential is necessary. The potential to the selective deposition of a metal can be calculated from the Nernst equation or it can be determined from data obtained by voltammetry.

Practically the metallic deposits should be smooth and strongly adherent so that the process of washing, weighing and drying could be performed without mechanic loss of the deposit. The deposits are affected in the physical characteristics by temperature, current density and the presence of complexing agents. Many electrogravimetric deposits based on the use of complexing agents have been found to form smoother and more adherent films. The Cyanide and ammonia complexes give the best deposits.