Congo Red

CAS Number573-58-0
Molecular FormulaC32H22N6Na2O6S2
Molecular Weight696.7
InChI KeyIQFVPQOLBLOTPF-UHFFFAOYSA-L
Synonyms
  • Congo red
  • 573-58-0
  • DIRECT RED 28
  • C.I. Direct Red 28
  • Congazone sodium
  • Benzo Congo Red
  • Haemomedical
  • Haemonorm
  • Hemorrhagyl
  • Solucongo
  • Sugai Congo Red
  • Atul Congo Red
  • Vondacel Red CL
  • Kayaku Congo Red
  • Mitsui Congo Red
  • Cotton Red L
  • Direct Red K
  • Azocard Red Congo
  • Congo Red H
  • Congo Red L
  • Congo Red M
  • Congo Red N
  • Congo Red R
  • Congo Red W
  • Congo Red CR
  • Congo Red WS
  • Atlantic Congo Red
  • Cotton Red 4BC
  • Cotton Red 5B
  • Erie Congo 4B
  • Tertrodirect Red C
  • Hispamin Congo 4B
  • Congo Red 4B
  • Congo Red 4BX
  • Red K
  • Diacotton Congo Red
  • Peeramine Congo Red
  • Trisulfon Congo Red
  • Direct Red DC-CF
  • Brasilamina congo 4B
  • Direct Red C
  • C.I. 22120
  • Kongorot
  • CCRIS 2277
  • Congo Red ICI
  • C.I. Direct Red 28, disodium salt
  • MFCD00004028
  • AI3-63036
  • CI Direct Red 28
  • 3U05FHG59S
  • DTXSID4022816
  • NSC-7232
  • sodium diphenyldiazo-bis-alpha-naphthylaminesulfonate
  • NSC-56651
  • 1-Naphthalenesulfonic acid,3,3'-[[1,1'-biphenyl]-4,4'-diylbis(azo)]bis[4-amino-, disodium salt
  • Disodium 3,3'-((1,1'-biphenyl)-4,4'-diylbis(azo))bis(4-aminonaphthalene-1-sulphonate)
  • Congo Red (90%)
  • Congo Red RS
  • Sodium diphenyldiazo-bis(alpha-naphthylaminesulfonate)
  • Kongorot [German]
  • DTXCID502816
  • Cerven kongo [Czech]
  • Cerven kongo
  • Cerven prima 28 [Czech]
  • DirectRed28
  • disodium 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate)
  • Cerven prima 28
  • CAS-573-58-0
  • Sodium 3,3'-([1,1'-biphenyl]-4,4'-diylbis(diazene-2,1-diyl))bis(4-aminonaphthalene-1-sulfonate)
  • Congo red [USP]
  • HSDB 4225
  • NCGC00159364-02
  • NSC 7232
  • EINECS 209-358-4
  • NSC 56651
  • UNII-3U05FHG59S
  • congo-red
  • C32H22N6Na2O6S2
  • Direct Congo Red
  • Congo Red (C.I. 22120)
  • Congo Red K
  • 1-NAPHTHALENESULFONIC ACID, 3,3'-((1,1'-BIPHENYL)-4,4'-DIYLDIAZO)BIS(4-AMINO-, DISODIUM SALT
  • 1-naphthalenesulfonic acid, 3,3'-([1,1'-biphenyl]-4,4'-diyldiazo)bis[4-amino-, disodium salt
  • Congo Red sodium salt
  • C.I.Direct Red 28
  • CONGO RED [MI]
  • CONGO RED [HSDB]
  • Congo Red, indicator grade
  • Natrium-salz der diphenyl-bis-azo-bis-naphthylamin-4-sulfonsaeure [German]
  • CONGO RED [MART.]
  • CONGO RED [WHO-DD]
  • Congo Red, certifiable grade
  • SCHEMBL25635
  • 1-Naphthalenesulfonic acid, 3,3'-((1,1'-biphenyl)-4,4'-diylbis(azo))bis(4-amino-, disodium salt
  • SCHEMBL202229
  • Congo Red, JIS special grade
  • Congo Red, analytical standard
  • CHEMBL429694
  • orb1308431
  • orb3139484
  • SCHEMBL29366109
  • SCHEMBL29395841
  • C32H22N6O6S2.2Na
  • CHEBI:34653
  • MSK5831
  • IQFVPQOLBLOTPF-UHFFFAOYSA-L
  • GLXC-20473
  • HMS5085C06
  • Congo Red, Dye content >=35 %
  • Natrium-salz der diphenyl-bis-azo-bis-naphthylamin-4-sulfonsaeure
  • SAI_0008
  • Tox21_111605
  • Tox21_202934
  • HB0737
  • AKOS000282971
  • AKOS016368576
  • AKOS024285600
  • FD03839
  • 1-Naphthalenesulfonic acid, 3,3'-(4,4'-biphenylenebis(azo))bis(4-amino-, disodium salt
  • NCGC00260480-01
  • DA-52047
  • disodium 4-amino-3-[[4-[4-[(1-amino-4-sulfonatonaphthalen-2-yl)diazenyl]phenyl]phenyl]diazenyl]naphthalene-1-sulfonate
  • SY010430
  • C.I. Direct Red 28, disodium salt (8CI)
  • NS00020843
  • Congo Red, High Purity - CAS 573-58-0
  • D89267
  • Q114391
  • Congo Red, BioXtra, certified by the Biological Stain Commission
  • Congo Red, for microscopy (Bact., Bot., Hist.), indicator (pH 3.0-5.2), Reag. Ph. Eur.
  • 1-Naphthalenesulfonic acid, 3,3'-((1,1'-biphenyl)-4,4'-diylbis(2,1-diazenediyl))bis(4-amino-, sodium salt (1:2)
  • 1-Naphthalenesulfonic acid, 3,3'-[[1,1'-biphenyl]-4,4'-diylbis(azo)]bis[4-amino-, disodium salt (9CI)
  • 3,3'-[[1,1'Biphenyl]-4,4'-diylbis(azo)-]bis[4-amino-1-naphthalenesulfonic acid] disodium salt
  • DISODIUM 3,3'-(BIPHENYL-4,4'-DIYLDIDIAZENE-2,1-DIYL)BIS(4-AMINONAPHTHALENE-1-SULPHONATE)
  • Disodium 3,3'-[[1,1'-biphenyl]-4,4'-diylbis(diazene-2,1-diyl)]bis(4-aminonaphthalene-1-sulfonate)
  • disodium 3,3'-[biphenyl-4,4'-diyldi(E)diazene-2,1-diyl]bis(4-aminonaphthalene-1-sulfonate)
  • disodium;4-amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]phenyl]phenyl]azo-naphthalene-1-sulfonate

Applications:

Uv-Vis Spectrum of Congo Red

April 8, 2026

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For optimal results in HPLC analysis, it is recommended to measure absorbance at a wavelength that matches the absorption maximum of the compound(s) being analyzed. The UV spectrum shown can assist in selecting an appropriate wavelength for your analysis. Please note that certain mobile phases and buffers may block wavelengths below 230 nm, rendering absorbance measurement at these wavelengths ineffective. If detection below 230 nm is required, it is recommended to use acetonitrile and water as low UV-transparent mobile phases, with phosphoric acid and its salts, sulfuric acid, and TFA as buffers.
For some compounds, the UV-Vis Spectrum is affected by the pH of the mobile phase.  The compound was dissolved with water. This analysis was done with the mobile phase made of 20% acetonitrile and 80% water.

 

 

Application Analytes:
Congo Red
SIELC Technologies usually develops more than one method for each compound. Therefore, this particular method may not be the best available method from our portfolio for your specific application. Before you decide to implement this method in your research, please send us an email to research@sielc.com so we can ensure you get optimal results for your compound/s of interest.