Chemical Name: Pyrogallol Red
Appearance: dark reddish-brown or dark purple powder
Sensitivity: pass test
MW: 400.36, C19H12O8S
Storage Condition: ambient temperature, protect from metal
Shipping Condition: ambient temperature
PR is a colorimetric reagent and indicator for heavy metal ions and rare earth metals. This reagent is hardly soluble in water and alcohol, and insoluble in organic solvents. The color of PR in aqueous solution is orange-red in weak acidic pH, yellow in neutral pH, and violet in alkaline pH. The aqueous PR solution turns red in the presence of Bi or Pb at acidic pH, and blue-violet in the presence of Co, Ni, and rare earth metal ions at neutral or alkaline pH. Its proton dissociation constants are reported to be pKa1=2.56, pKa2=6.28, pKa3=9.75 and pKa4=11.94.
Chelate titration: Bi, Co, Ni, Pb, rare earth metals
Precipitation titration: Br-, Cl-, I-, SCN
Colorimetry: Ag, Al, Cu, Fe, Ge, In, Mo, Sb, Ti, U, V, W, rare earth metals
1. J. Medina-Escriche, et al., Spectrophotometric Study of the Cerium(IV) - Pyrogallol Red System. Analyst. 1985;110:807-810.