Science Fair Project Encyclopedia
Bromophenol blue, Tetrabromophenolsulfonphthalein, is an acid-base indicator whose useful range as an indicator lies between pH 3.0 and 4.6. It changes from yellow at pH 3.0 to purple at pH 4.6; this reaction is reversible.
Bromophenol blue is also used as a color marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as DNA or protein in a gel. (Xylene cyanol may be used for this purpose as well.)
It is sometimes referred to as bromphenol blue as well.
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