Product code RXSOL-60-6604-698
HYDROXY NAPTHOL BLUE indicator for calcium determination
HYDROXY NAPTHOL BLUE indicator for calcium determination is make by Dissolve 0.3 g in 100 mL of water, add 10 mL of 1 N sodium hydroxide volumetric solution and 1.0 mL of calcium chloride solution (1 g in 200 mL), and dilute with water to 165 mL.
Application
Binding of Transition Metal Ions by the Calcium Indicator Hydroxy Naphthol Blue. It has been found that the calcium indicating azo-dye, hydroxy naphthol blue (HNB), binds more strongly to transition metal ions than to the alkaline earth ions it is currently used for.
Dosage
At pH 10, Ca2+(aq) ion first complexes with the indicator as CaIn+(aq) which is wine red. As the stronger ligand EDTA is added, the CaIn+(aq) complex is replaced by the CaY2-(aq) complex which is blue. The end point of titration is indicated by a sharp colour change from wine red to blue.