Bromocresol Green

WHAT IS BROMOCRESOL GREEN?

Bromocresol Green (BCG) is a pH sensitive triphenylmethane dye that belongs to a class of dyes called sulfonephthaleins which are very well known Ph indicators.

Bromocresol Green is a pH indicator used in applications such as growth mediums for microorganisms and titrations. It is commonly used as a diagnostic technique to measure serum albumin concentration within human blood samples in possible cases of renal failure and liver disease.

USES OF BROMOCRESOL GREEN

BCG is used as a tracking dye for DNA agarose gel electrophoresis, in protein determinations and in charge-transfer complexation processes. In TLC staining, Bromocresol Green is used for visualisation of the compounds with functional groups whose pKa is below 5.0.

PROPERTIES OF BROMOCRESOL GREEN

When dissolved in water or in aqueous solution, bromocresol green will ionize to give the monoanionic form (yellow), that further deprotonates at higher pH to give the dianionic form (blue), which is stabilized by resonance: Tap water is sufficiently basic to give a solution of bromocresol green its characteristic blue-green color.

The acid and basic forms of BCG form an isosbestic point that indicates that the two forms interconvert directly without forming any other substance.The isosbestic point occurs where the acid and basic forms and intermediate pH solutions thereof have the same absorbance and the analytical concentration of the dye is the same in all solutions.

Bromocresol green may cause irritation and so skin and eye contact should be avoided.