Many metal ions form stable complexes with EDTA and this enables them to be determined by a compleximetric titration.

The end-point of an EDTA complexometric titration can be detected by means of a metal ion indicator – an organic dye which changes colour when it binds with metal ions. For it to be suitable in an EDTA titration, the indicator must bind less strongly with metal ions than does EDTA. This particular reaction uses murexide, which canges from pink to blue at the end point

Determination of nickel – pupil guide

Determination of nickel – Teacher’s guide

Determination of nickel – Risk assessment