Indicator electrodes detect and respond to changes in the analyte of interest within a sample solution in electrochemical measurements. These electrodes play a pivotal role in various electrochemical techniques, such as potentiometry and voltammetry.
Indicator electrodes interact with the analyte to generate electrical signals for measuring and quantifying target species. Examples include glass electrodes for pH and metal electrodes for redox reactions.
1. Metal Electrodes
Construction: Typically, manufacturers make metal electrodes from a metal of interest (e.g., platinum, gold, or silver), and they usually shape them as wires or rods
Working Principle: These electrodes are selective for redox reactions involving specific metal ions.The metal electrode actively participates in the redox reaction, and you measure the potential difference between the metal and a reference electrode to determine the analyte concentration.
2. Glass Electrode (pH Electrode)
Construction: A glass electrode consists of a thin glass membrane at the tip, a reference electrode (usually Ag/AgCl), and a junction solution, typically KCl. The glass membrane contains a special glass sensitive to H+ ions.
Working Principle: The potential of the glass electrode depends on the H+ ion concentration. The glass membrane selectively interacts with H+ ions, generating a potential difference with the reference electrode. This potential difference is used to determine the pH of the solution.
Indicator electrodes interact with the analyte to generate electrical signals for measuring and quantifying target species. Examples include glass electrodes for pH and metal electrodes for redox reactions.
