Phenol red

Phenol red belongs to the class of triphenylmethane dyes and is a widely used pH indicator and biological reagent, valued for its clear colorimetric response over a pH range of 6.8 to 8.4, transitioning from yellow to red. It is commonly employed in cell culture media to monitor pH changes during cell growth and metabolism, ensuring optimal conditions for biological assays. Widely used in culture media, phenol red identifies pH changes from neutral (red) to acidic (yellow) values. Typically a change in color from red to yellow indicates high rates of cellular death when used in tissue cultures. Beyond its role as a pH indicator, phenol red serves in analytical chemistry for titrations, as a visual marker in enzyme activity assays, and in the development of colorimetric sensors. In different protocols, it is used to detect hydrogen peroxide. Visual transition intervals: 1.2-3.0, brown-orange to yellow (1st transition range); 6.5-8.0, brownish-yellow to red-violet (2nd transition range).