Phenol Red

General description

Phenol Red is a phenolsulfonphthalein compound. It is present as a sulfonated hydroxyquinone in weakly acidic aqueous solutions. In alkaline solutions, the dye forms a hydrophilic dianion (a small, red anion that has a larger conjugated system than the yellow hydroxyquinone).

Application

Phenol red is commonly used as a pH indicator in biology and medicine. It is incorporated into microbiological culture media for the identification of Escherichia coli strains. Its clinical diagnostic applications include the investigation of gastric and duodenal ulcers and the assessment of tear function in ophthalmology. Phenol red is also used as a tracer to assess the permeability of the ileal mucosal membrane and to assess bacterial leakage through root-filling materials in dentistry.
Phenol Red has been used for the preparation of phenol red gavage meal for measurement of gastric emptying in rats.

Suitable for use as a pH indicator.

Biochem/physiol Actions

Phenol Red is a pH indicator which changes color from yellow to red.