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Bromocresol Purple Sodium Salt (62625-30-3)

Bromocresol Purple (Sodium Salt) Chemical Structure

What is Bromocresol purple?

Bromocresol purple (BCP), also referred to as 5,5″-dibromo-o-cresolsulfophthalein, is a member of the class of 2,1-benzoxathioles and is a pH sensitive dye of the triphenylmethane family (triarylmethane dyes). It is a hydrophilic dye used as a pH indicator and for several purposes including the determination of serum albumin concentrations. It has a pKa value of 6.3.

Macsen Laboratories is the leading manufacturer and supplier of Bromocresol Purple Sodium Salt with ISO certification.
Name of Product Bromocresol purple Sodium Salt
IUPAC Name sodium;2-[(E)-(3-bromo-4-hydroxy-5-methylphenyl)-(3-bromo-5-methyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]benzenesulfonate
Synonyms 5′,5′′-Dibromo-o-cresolsulfonephthalein; Bromocresol Roxo; Púrpura de bromocresol; Bromocresol Purpura; Pourpre de bromocrésol; Bromcresol purple
CAS No 62625-30-3
Molecular Formula C21H15Br2NaO5S
Molecular Weight 562.2 g/mol
Pubchem CID 23665568
Pubchem SID 480474274


SR. No Criteria Limit/Specification
1 Appearance (form) Solid Powder
2 Appearance (color) Brown to Dark Orange
3 Solubility (0.1% (EtOH)) Clear solution
4 Transition Range pH 5.2 – pH 6.8 (Yellow to Purple)
5 Absorptivity 1%/1cm
(0.1N NAOH, at λmax 587.8nm)
6 Loss on drying at 110°C (1 hr) NMT 5.0 %
7 Dye content by Spectrophotometry >90%


  • Bromocresol purple is used as a pH indicator owing to its property of being colored yellow below pH 5.2 and violet above pH 6.8.
  • In medical laboratories, it is used to measure serum albumin.
  • It is mainly used as a fluorescent stain for yeast cells.
  • In the field of microbiology, it is utilized for staining dead cells, as well as for the isolation and testing of lactic acid bacteria.
  • Bromocresol purple can also be used in photographic processing.


Q. What is the pH range of Bromocresol purple indicator?

Bromocresol purple (BCP) is a triarylmethane dye, with a transition range of pH 5.2 to 6.8. It is yellow in acidic solutions (below pH 5.2) and violet in basic solutions (above pH 6.8).

Q. What is the absorption spectrum of Bromocresol purple?

Bromocresol purple shows an absorbance peak at 212 nm.

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