Advantages And Disadvantages Of Polarography

Polarography:
A method that measures the current flowing between the two electrodes and the voltage to determine the nature and the concentration of the solute in a solution under controlled conditions is called as polarography. It was discovered by Jaroslav Heyrovsky. Because of the renewable surfaces and wide cathode ranges, the electrode used can be dropping mercury electrode or static mercury drop electrode. Mercury is used as an electrode because of its wide range of negative potential, the ability to reversibly reducing a metal ion into mercury and regeneration of the surface by producing a drop or film.
Polarography is of three types of electrodes:
1– Hanging mercury drop electrode
2– Dropping mercury electrode
3- Static mercury drop

On the other hand, there are many disadvantages such as the mercury electrodes tend to malfunction because of clogging when mercury is oxidized by air, also toxicity may occur because of the use of mercury, it has a limited potential and a small capillary that can be easily blocked, the oxidation of mercury can easily happen and the mercury used must be highly pure. Types of currents in Polarography:
1 – Direct current polarography
In this type a current will flow through a cell containing analyte and a supporting electrolyte, a current voltage curve is obtained by the use of dropping mercury electrode. It gives accurate results for the moderate concentrations but limited application on lower concentrations due to large rhythmic fluctuations. When voltage applied to the cell increases, a small residual current flows until the substances undergo reduction or oxidation. At first the current increases linearly with the voltage then it gradually reaches a limit value. A saw tooth pattern is