Polarography is a classical voltammetric technique used to analyze electrochemical reactions. This method applies a linear potential sweep to a dropping mercury electrode (DME), and the resulting current is measured. A dropping mercury electrode is commonly used as the working electrode in polarography. It consists of a capillary tube filled with mercury, where the tiny droplet forms at the tip. This droplet continuously drops from the capillary, creating a new electrode surface for each measurement.

During a polarographic measurement, the potential applied to the DME varies linearly over time. As the potential changes, the electroactive species present in the solution undergo reduction or oxidation reactions at the electrode surface, depending on the applied potential. The resulting current is plotted against the potential, creating a current-potential curve known as the polarogram. Polarography has been used in various fields, including analytical chemistry, environmental analysis, and electrochemical research.

Hydrodynamic voltammetry differs from polarography in that a metal electrode is used instead of the mercury drop electrode as a solid working electrode. This technique applies a potential to the solid working electrode, and the resulting current is measured. A voltammogram is obtained by varying the potential over a specific range, which yields a current plot as a function of the applied potential. Unlike polarography, hydrodynamic voltammetry eliminates the current oscillations observed in polarograms due to the formation of mercury drops.