bromophenol blue

noun

bro·​mo·​phe·​nol blue ˌbrō-mō-ˌfē-ˌnōl-  -ˌnȯl- 

-fi-

variants also bromphenol blue

(ˌ)brōm- 

: a dye C₁₉H₁₀Br₄O₅S obtained as pinkish crystals and used as an acid-base indicator