<P> 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 . </P>
what is the purpose of the bromophenol blue dye in the samples
a pH indicator a color marker a dye