Chelatometry

Chelatometry is a type of complexometric titration in which the titrant is a complexing agent. This method is primarily used for the quantitative determination of metal ions. The most common titrant used in chelatometry is ethylenediaminetetraacetic acid, or EDTA. EDTA is a chelating agent that can form stable, soluble complexes with most metal ions. The reaction between a metal ion and EDTA typically involves the formation of a coordination complex where the metal ion is bonded to the nitrogen and oxygen atoms of the EDTA molecule.

The titration is usually carried out in a buffered solution to maintain a constant pH, as the stability of metal-EDTA complexes can be pH-dependent. An indicator is often used to signal the endpoint of the titration. These indicators are usually organic molecules that form colored complexes with metal ions, and their color changes when they are displaced by EDTA at the endpoint. Alternatively, potentiometric or conductometric methods can be used to detect the endpoint.

Chelatometry is a versatile analytical technique with applications in various fields, including water analysis, pharmaceuticals, and food chemistry. It is employed to determine the concentration of various metal ions such as calcium, magnesium, zinc, and copper. The accuracy and convenience of chelatometry make it a widely adopted method for quantitative analysis.