3D model (JSmol)
|Molar mass||698.01 g·mol−1|
|Appearance||Beige to brown powder|
|Melting point||225 °C (437 °F; 498 K) decomposes|
|Solubility in other solvents||Soluble in benzene; very soluble in ethanol and diethyl ether|
|UV-vis (λmax)||423 nm|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
|Bromocresol green (pH indicator)|
|below pH 3.8||above pH 5.4|
Bromocresol green (BCG) is a dye of the triphenylmethane family (triarylmethane dyes). It belongs to a class of dyes called sulfonephthaleins. It is used as a pH indicator in applications such as growth mediums for microorganisms and titrations. In clinical practise, it is commonly used as a diagnostic technique. The most common use of Bromocresol green is to measure serum albumin concentration within mammalian blood samples in possible cases of renal failure and liver disease.
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:
An ethanol solution (0.04 wt%) of bromocresol green has been proposed for TLC staining and is suitable for visualisation of the compounds with functional groups whose pKa is below 5.0 (carboxylic acids, sulfonic acids, etc.). These appear as yellow spots on a light or dark blue background; no heating is necessary. Bromophenol blue solution can be used for the same purpose.
The compound is synthesized by bromination of cresol purple (m-cresolsulfonphthalein).
It is used as a pH indicator and as a tracking dye for DNA agarose gel electrophoresis. It can be used in its free acid form (light brown solid), or as a sodium salt (dark green solid). It is also an inhibitor of the prostaglandin E2 transport protein. Additional applications include use in sol-gel matrices, the detection of ammonia, and the measurement of albumin in human plasma and serum.
Bromocresol green may cause irritation. Skin and eye contact should be avoided.
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- "BCG (Bromocresol Green) Albumin Assay Kit" (PDF). Sigma Aldrich. 2014.