15 Chromogen/Metal Indicator



Metal Indicator

  • Product code
    T021  Tiron
  • CAS No.
  • Chemical name
    1,2-Dihydroxy-3,5-benzenedisulfonic acid, disodium salt, monohydrate
  • MW
Unit size Price Item Code
5 g T021-10


Tiron is used as a metal indictor of Fe, and as a colorimetric reagent of Fe, Al, Ti, and other metal ions. Tiron is readily soluble in water as a colorless solution. The pKa2 is reported to be 12.6 (μ=0.1, 20ºC). Tiron forms colored chelates with Fe, Ti, and other metal ions. The color of the Fe complex is blue at pH 1-4 (1:1, logK=20.4), purple at pH 5-7 (1:2, logK=15.1), and red at pH 7 or over (1:3, logK=10.8).

Technical info

Chelate titration: Fe
Colorimetry: Al, B, Co, Cu, Fe, Ga, Mo, Nb, Os, Sr, Ti, UO2(II), V
Fluorometry: rare earth metals
Masking reagent: Al, Cr, Fe, Ti


Open References

1) K. Ueno, T. Imamura and K. L. Cheng, "Handbook of Organic Analitical Reagents 2nd Edition", CRC Press, 1992.
2) G. F. Atkinson and W. A. E. McBryde, "Oxidation of the Analytical Reagent Tiron (Disodium-4,5-Dihydroxybenzene-1,3-Disulphonate)", CanJ. Chem., 1957, 35, 477. 
3) P. N. R. Nichols, "The Photometric Determination of Titanium with Tiron", Notes, 1960, 85, 452. 
4) L. J. Clark, "Titanium Determination with Disodium-1,2-Dihydroxybenzene-3,5-Disulfonate (Tiron) in Oxalic Acid Solution", Anal. Chem., 1970, 42, 694. 

Handling and storage condition

Appearance: White powder or crystal
Purity (Titration): ≧ 98.0 %
Solubility in water: To pass test (clear, colorless)
Sulfated ash: 40.0 - 46.0 %
Absorbance (Ti complex): ≧ 0.280 (around 380 nm)
Sensitivity: To pass test
IR spectrum: Authentic
Handling and storage condition
Ambient temperature

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