Murexide (ammonium purpurate) was found to function as an indicator for the complexometric determination of Th. Ammonium purpurate forms a yellow complex with Th that turns pink when an excess drop of EDTA is added to it. Interfering ions are listed.

How do you use murexide indicator?

A ground mixture of dye powder and sodium chloride (NaCl) provides a stable form of the indicator. Prepare by mixing 200 mg murexide with 100 g solid NaCl and grinding the mixture to 40 to 50 mesh. Titrate immediately after adding indicator because it is unstable under alkaline conditions.

Why is murexide a suitable indicator?

Why is Murexide a suitable indicator? ... The indicator used is murexide which is a different colour when freq compared to its colour when it is attached to Ni2* ions. Murexide is a suitable indicator since it binds less strongly to the Ni2* ions than does EDTA.