15 Chromogen/Metal Indicator



Metal Indicator

  • Product code
    P012  PR
  • CAS No.
  • Chemical name
    Pyrogallol sulfonphthalein
  • MW
Unit size Price Item Code
1 g $request P012-10

1 g
Quantity may be adjusted within the cart.

Product Description

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.

Chemical Structure

Technical info

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


Open References

1) J. Medina-Escriche, A. Sevillano-Cabeza and M. A. Martin Penella, "Spectrophotometric Study of the Cerium(IV) - Pyrogallol Red System", Analyst, 1985, 110, 807.

Handling and storage condition

Appearance: Dark reddish brown to black purple powder
Solubility in Methyl alcohol: To pass test (clear, dark red)
Absorbance: ≧ 0.330 (around 505 nm)
Sulfated ash: ≦ 1.0 %
Sensitivity: To pass test
IR spectrum: Authentic
Handling and storage condition
Ambient temperature

Product Classification

Product Classification

Search word