The dye phenol red (phenolsulphonphthalein) was chemically brominated to bromophenol blue (3′, 3 ″, 5′, 5 ″-tetrabromophenolsulphonphthalein) directly by hydrogen peroxide (20 mM or higher) under acidic pH (0.5–4.5) and moderate temperature (30° C). Since this bromination reaction takes place in the absence of any chemical or biological catalyst, the results represent an important warning concerning a commonly used assay for detecting ...
