溴酚蓝，分子式：C19H10Br4O5S，浅黄色到棕黄色粉末；易溶于NaoH溶液，溶于甲醇、乙醇和苯，微溶于水(约0.4g/100ml)，最大吸收波长422nm。一种pH 指示剂，在pH 3.0~4.6范围，颜色由黄变蓝。常用做电泳指示染料，凝胶中电泳迁移速度在小分子核酸或蛋白质区域。

常温保存，有效期12个月

Bromophenol blue (3′,3″,5′,5″-tetrabromophenolsulfonphthalein, BPB, albutest) is used as a pH indicator, a color marker, and a dye. It can be prepared by slowly adding excess bromine to a hot solution of phenolsulfonphthalein in glacial acetic acid.

As an acid–base indicator, its useful range lies between pH 3.0 and 4.6. It changes from yellow at pH 3.0 to blue at pH 4.6; this reaction is reversible. Bromophenol blue is structurally related to phenolphthalein (a popular indicator).