Dichlorofluorescein (DCF) is an organic dye of the fluorescein family, being substituted at the 2 and 7 positions by chloride.

[1][2] When used as an indicator, upon reaching the equivalence point of a titration reaction the color shifts from colorless towards a faint pink.

Dichlorofluorescin (DCFH) is a probe that is trapped within cells and is easily oxidized to fluorescent dichlorofluorescein (DCF).

The method measures the ability of compounds to prevent the formation of DCF by 2,2'-Azobis(2-amidinopropane) dihydrochloride (ABAP)-generated peroxyl radicals in human hepatocarcinoma HepG2 cells.

[3] By itself, dichlorofluorescin (DCFH) also quantifies intracellular hydrogen peroxide as well as cellular oxidative stress.