19 Biochemicals



Detection Reagent for SH Moiety

  • Product code
    D029  DTNB
  • CAS No.
  • Chemical name
    5,5'-Dithiobis(2-nitrobenzoic acid)
  • MW
Unit size Price Item Code
1 g D029-10


DTNB is known as Ellman’s reagent. It is used for the colorimetric determination of thiol groups in biological samples. It is fairly soluble in water. Colorless DTNB is converted to yellow 5-Mercapto-2- nitrobenzoic acid in the presence of thiol compounds (Fig. 1). As 5-Mercapto-2-nitrobenzoic acid has an absorption maximum at 412 nm, the absorption spectrum of DTNB does not interfere with thiol detection (Fig. 2).

Fig. 1 DTNB reaction with thiol compound

Fig. 2 Absorption spectra of DTNB and reduced DTNB


Open References

1. D. R. Grassetti, et al., Determination of Sulfhydryl Groups with 2, 2 E or 4, 4 EDithiodipyridine. Arch Biochem Biophys. 1967;119:41-49.
2. R. E. Humphrey, et al., Spectrophotometric Determination of Sulfite with 4, 4 EDithiodipyridine and 5, 5 EDithiobis-(2-nitrobenzoic acid). Anal Chem. 1970;42:698-702.
3. R. E. Humphrey, et al., Spectrophotometric Determination of Cyanide with Organic Disulphides. Talanta. 1971;18:491-497.
4. T. Uete, et al., Spectrophotometric Micromethod for Measuring Cholinesterase Activity in Serum or Plasma. Clin Chem. 1972;18:454-458.

Handling and storage condition

Appearance: Pale yellow crystalline powder
Solubility in ethyl alcohol: To pass test (clear, pale yellow)
Absorbance: ≦ 0.195 (420 nm)
Solubility in Phosphate buffer: To pass test (clear, pale yellow)
Molar absorptivity: ≧ 12,000 (around 305 nm)
m.p.: 237 - 247oC (dec.)
Loss on drying (105°C): ≦ 1.0 %
Sulfated ash: ≦ 0.10 %
IR spectrum: Authentic
Handling and storage condition
Ambient temperature

Product Classification

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