How To Make Bromocresol Green Indicator

Recipe for Bromocresol Green pH Indicator Solution

This is the chemical structure of bromocresol green.
This is the chemical structure of bromocresol green.

Bromocresol green (BCG) is a triphenylmethane dye that is used as a pH indicator for titration, DNA agarose gel electrophoresis, and microbiological growth media. Its chemical formula is C21H14Br4O5S. The aqueous indicator is yellow below pH 3.8 and blue above pH 5.4.

This is the recipe for bromocresol green pH indicator solution.

Bromocresol Green pH Indicator Ingredients

  • 0.1 g of bromocresol green
  • ethyl alcohol

Prepare the Bromocresol Green Solution

0.1% in alcohol

  1. Dissolve 0.1 g of bromocresol green in 75 mL of ethyl alcohol.
  2. Dilute the solution with ethyl alcohol to make 100 ml.

0.04% aqueous

  1. Dissolve 0.04 g of bromocresol green in 50 mL of deionized water.
  2. Dilute the solution with water to make 100 ml.

While bromocresol green is usually dissolved in ethanol or water, the dye is also soluble in benzene and diethyl ether.

Safety Information

Contact with bromocresol green powder or indicator solution may cause irritation. Contact with skin and mucous membranes should be avoided.