Cu-PAN, a mixture of Cu-EDTA and pyridylazo-naphthol PAN, is a very popular metal indicator for chelatometry. Usually, 20-50% aqueous dioxane (or isopropyl alcohol) or 50-70% aqueous methanol (or ethanol) is used as a solvent (1 g Cu-PAN per 100 ml solvent). The solution should be heated during the chelating titration.
Chelate titration (acidic condition): Al, C, Co, Fe(III), Ga, Hg, In, Ni, V, Zn, rare earth metal ions
Chelate titration (alkaline condition): Ca, Cu, Mg, Mn(II)
1) H. Flaschka, et al., EDTA Titrations Using Copper-PAN Complex as Indicator. Chem Anal. 1956;45:58-61.