Bromocresol Green Chemical Structure

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What is Bromocresol Green?

Bromocresol Green (BCG) is a pH sensitive dye of the triphenylmethane family (triarylmethane dyes). It belongs to a class of dyes called sulfonephthaleins. It shows yellow color below pH of 3.8 and blue color above pH of 5.4 and is thus useful as a pH indicator. The pKa of bromocresol green is 4.90.

Macsen Laboratories is the leading manufacturer and supplier of Bromocresol Green with ISO certification.
Name of Product Bromocresol Green
IUPAC Name 2,6-dibromo-4-[3-(3,5-dibromo-4-hydroxy-2-methylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-3-methylphenol
Synonyms Bromocresolgreen; 3',3'',5',5''-Tetrabromo-m-cresolsulfonephthalein; Tetrabromo-m-cresolphthalein sulfone; Bromocresol Verde; Verde de bromocresol; Vert de bromocrésol
CAS No 76-60-8
Molecular Formula C21H14Br4O5S
Molecular Weight 698.0 g/mol
Pubchem CID 6451
Pubchem SID 475775546


SR. No Criteria Limit/Specification
1 Appearance (form) Solid Powder or Crystals
2 Appearance (color) Beige to brown
3 Odor Odorless
4 Solubility Very soluble in Ethanol and Diethyl Ether
Soluble in benzene
Sparingly soluble in water
5 Melting Point 225 °C (437 °F; 498 K)
6 Acidity (pKa) 4.90
7 UV-vis (λmax) 423 nm


  • The most prevalent application for bromocresol green is in the determination of the concentration of serum albumin present in mammalian blood samples taken from patients suspected of having kidney failure or liver disease.
  • Bromocresol Green is used as a pH indicator and as an active tracking dye for DNA Agarose gel electrophoresis.
  • Additionally, it acts as an inhibitor of the protein that transports prostaglandin E2.
  • In thin-layer chromatography (TLC), it is put to use for visualizing molecules that contain functional groups with pKa values lower than 5.
  • Additional uses include the detection of ammonia as well as utilization in sol-gel matrices.


Q. At what pH does bromocresol green change color?

Bromocresol green (BCG) is a sulfonphthalein dye, with a transition range of pH 3.8 to 5.4. It is yellow in acidic solutions (below pH 3.8) and blue in basic solutions (above pH 5.4).

Q. How does bromocresol green work with albumin?

Albumin in the presence of bromocresol green at a slightly acidic pH causes the indicator to change color from yellow-green to green-blue. The intensity of the color produced is related to the concentration of albumin in the sample.

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