Calcon indicator is a complexometric indicator. It is an azo-compound , resulting from the coupling reaction between a diazonium salt of an amino-naphthol, 2-amino-1-naphthol.
Calcon indicator is a complexometric indicator that has chemical formula C20H13N2NaO5S, used for the determination of aluminum , iron and zirconium It is an azo-compound , resulting from the coupling reaction between a diazonium salt of an amino-naphthol, 2-amino-1-naphthol and one of the so-called "letter acids" .