5,5'-Dithiobis(2-nitrobenzoic acid) (Ellmans reagent, DTNB), Pierce™

Supplier: 0000013509
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Synonyms: DTNB, Ellman's reagent, 5,5'-Disulfanediylbis(2-nitrobenzoic acid), 3,3'-Dithiobis(6-nitrobenzoic acid), 5,5'-Disulphanediylbis(2-nitrobenzoic acid), 2,2'-Dinitro-5,5'-dithiodibenzoic acid

22582
PI22582EA 150.15 USD
PI22582
5,5'-Dithiobis(2-nitrobenzoic acid) (Ellmans reagent, DTNB), Pierce™
5,5'-Dithiobis(2-nitrobenzoic acid) (Ellmans reagent, DTNB)

Thermo Scientific Pierce Ellman's Reagent (DTNB) reacts with sulfhydryl groups to yield a colored product, providing a reliable method to measure reduced cysteines and other free sulfhydryls in solution.


  • Sulfhydryl assay—reacts quantitatively with free (reduced) sulfhydryl groups (—SH) to yield detectable TNB product
  • Colorimetric detection—colored product enables spectrophotometric measurement in cuvettes or microplates (λmax = 412nm; ε = 14,150/M·cm)
  • Proven method—well-characterized chemistry provides quantitation of peptide or protein sulfhydryl groups using extinction coefficient calculation or by comparison to a cysteine


Ellman's Reagent (5,5'-dithio-bis-[2-nitrobenzoic acid]) is used to estimate sulfhydryl groups in a sample by comparing to a standard curve of a sulfhydryl-containing compound such as cysteine. Alternatively, sulfhydryl groups can be assayed using the extinction coefficient of TNB (14,150M-1 cm-1 at 412nm). Ellman's Reagent has been used for applications other than sulfhydryl estimation, such as for determining alkylthiols by HPLC using a pre-column derivatization procedure and to study thiols in the active site of several enzymes.

Formula: C₁₄H₈N₂O₈S₂
MW: 396.36 g/mol
Melting Pt: 240…244 °C
Storage Temperature: Ambient
MDL Number: MFCD00007140
CAS Number: 69-78-3
EINECS: 200-714-4

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