Potentiometry is a type of electrochemical analysis that utilizes the measurement of electrical potentials to detect and quantify an analyte. It involves the use of an electrode system consisting of a reference electrode and a measurement electrode. The reference electrode serves as a stable potential source and is typically composed of a metal electrode immersed in a solution containing a known concentration of a specific ion, such as a silver/silver chloride electrode in potassium chloride solution.
The measurement electrode is placed in contact with the solution containing the analyte, and the potential difference between the two electrodes is measured using a high-impedance voltmeter. The measured potential is proportional to the concentration of the analyte in solution, according to the Nernst equation.
In potentiometry, the analyte is detected without direct chemical reaction, making the technique non-destructive and suitable for analyzing fragile or unstable samples. It is also highly sensitive, with detection limits often in the nanomolar or even picomolar range.
Potentiometry is commonly used in the pharmaceutical industry for pH measurements, titrations, and quality control testing, as well as in environmental monitoring for assessing the concentration of contaminants in water or air.