Fenolröd

Fenolröd, or phenol red, is a pH indicator dye widely used in biology and chemistry. It is commonly added to cell culture media and other buffered solutions to provide a visual readout of pH changes.

Color depends on the acidity or basicity of the solution. The dye has a typical working range from about pH 6.8 to 8.2, shifting from yellow in more acidic solutions to red or pink in more basic ones. In many media, the color transition around physiological pH (near 7.0–7.4) is used to monitor culture conditions.

Applications: In mammalian cell culture (for example DMEM, RPMI-1640) phenol red allows quick assessment of medium pH as cells metabolize and CO2/bicarbonate levels fluctuate. It is also used as a general pH indicator in analytical experiments. Some researchers use phenol red-free media when experiments involve estrogen signaling or sensitive colorimetric assays due to reports that phenol red can exhibit weak estrogenic activity in vitro.

Safety and handling: Phenol red is a dye and should be handled with standard laboratory precautions. It is typically used at low concentrations and is not highly toxic in typical exposures, but avoid ingestion and eye contact and dispose according to local regulations.