LITTLE KNOWN FACTS ABOUT METAL INDICATORS.

The blue colour of calmagite at pH =10 is modified to red by addition of Mg- ion. The transform remaining reversible,Calmagite and Eriochrome BlackT (EBT) are this kind of indicators that modify from blue to pink whenever they advanced with calcium or magnesium. The endpoint of the complexometric EDTA titration working with both Calmagite or EBT