A triphenylmethane dye used to indicate pH level for titration, DNA agarose gel electrophoresis and microbiological growth mediums, bromocresol green (BCG) has aqueous indicators of blue (higher than 5.4 pH) or yellow (lower than 3.8 pH). BCG belongs to the sulfonephthaleins class of dyes. Bromocresol green is commonly used to measure the serum concentration of albumin in blood samples of people with liver disease or renal failure.
Bromocresol green also inhibits transport protein prostaglandin E2, an action that may reduce formation of blood clots. It is recommended that users of BCG wear gloves and goggles as contact with this substance may cause skin or eye irritation.
Another type of bromocresol called bromocresol purple (BCP) is also a dye and pH indicator belonging to the triphenylmethane family of dyes. BCP turns yellow when pH is below 5.2 and violet when pH is above 6.8. Bromocresol purple measures albumin and may have advantages over bromocresol green when applied to microbiological applications. BCP stains dead cells according to acidity of the cells and isolates and assays lactic acid bacteria.