A sulfonephthalein dye known as a pH indicator, listed as a buffering agent.
What it is
Phenolsulfonphthalein, known as phenol red, is a synthetic sulfonephthalein dye best known as a pH indicator that changes from yellow to red as the pH rises. CosIng lists it as a buffering agent.
Where it is used
Appears on the ingredient lists of a small number of products.
Limits of interpretation
The INCI list shows which ingredients are present, not how much of each. Above 1%, ingredients are listed in descending order of weight; below 1% the order is free.
The colour it shows in a product can depend on the pH.
Functions
- Buffering
- Stabilising the pH of an aqueous medium in a narrow range even if an acid or base is added. Altering and/or maintaining a cosmetic product's pH at the desired level.
EU regulation
This ingredient is not listed in the annexes of Regulation (EC) No 1223/2009 in the CosIng data.