A complexometric indicator is an ionochromic dye that undergoes a definite color change in presence of specific metal ions.
[2] In analytical chemistry, complexometric indicators are used in complexometric titration to indicate the exact moment when all the metal ions in the solution are sequestered by a chelating agent (most usually EDTA).
Some complexometric indicators are sensitive to air and are destroyed.
When such solution loses color during titration, a drop or two of fresh indicator may have to be added.
Some examples are: In some settings, when the titrated system is a redox system whose equilibrium is influenced by the removal of the metal ions, a redox indicator can function as a complexometric indicator.