Bromophenol blue

Bromophenol blue is a pH indicator and dye that is primarily used in laboratories. It is a member of the triphenylmethane dye family and is derived from phenol. Bromophenol blue is used in a variety of scientific applications, including electrophoresis, protein quantification, and as a pH indicator in cell cultures and other biological experiments.

Chemical properties

Bromophenol blue has the chemical formula C19H10Br4O5S. It is a dark purple solid at room temperature and is soluble in water, alcohol, and slightly soluble in ether. The compound has a molecular weight of 669.96 g/mol. It is a weak acid, with a pKa of 4.0 in water.

Uses

Bromophenol blue is used as a tracking dye in DNA sequencing and polyacrylamide gel electrophoresis. It is also used in the Bradford protein assay, a colorimetric assay used to measure the concentration of total protein in a sample. In this application, bromophenol blue binds to proteins, causing a shift in the dye's absorption maximum and a change in color.

As a pH indicator, bromophenol blue changes color depending on the pH of the solution it is in. It is yellow in acidic solutions (pH < 3.0), green in neutral solutions (pH 4.0 - 6.0), and blue in basic solutions (pH > 6.0).

Safety

Bromophenol blue is considered safe for laboratory use, but it can be harmful if swallowed, inhaled, or comes into contact with skin or eyes. It is recommended to use personal protective equipment when handling this chemical.

See also

• Phenol red
• Methyl blue
• Coomassie Brilliant Blue