Bromthymol blue shine alamar pH, wanda ke nufin cewa abu ne wanda ke canza launi don amsa canje-canje a cikin acidity ko asali (pH) na bayani. Rini ne na roba wanda aka fi amfani dashi a gwaje-gwajen dakin gwaje-gwaje don nuna pH na bayani. Bromthymol blue yana canza launi daga rawaya zuwa shuɗi yayin da pH na bayani yana ƙaruwa daga acidic zuwa asali. Hakanan ana amfani dashi azaman mai nuni a gwaje-gwajen likita don gano canje-canje a cikin pH na ruwan jiki.