Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a pH indicator. In its sultone form, it has a pKa value of 6.3,[1] and is usually prepared as a 0.04% aqueous solution.

Biological Stain
pH Indicator

Minimum Assay: 90%
Molecular Formula: C21H16Br2O5S
Molecular Weight: 540.22 g/mol
Melting Point: 240°C

Visual Transition Interval:

From pH 5.2 (Yellow)

To pH 6.8 (Purple)

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 115-40-2
Einecs No: 204-087-8