product description： m-cresol purple sodium salt (MCP) is a colorimetric pH indicator dye. The dye is blue in anionic form and yellow in protonated form. application： m-Cresol purple sodium salt is used to detect changes in pH during titrations at which color changes occur at pH 7.6-9.2. Upon bromination, m-cresol purple sodium salt creates the dye bromocresol green which is used as a tracking dye in DNA agarose gel electrophoresis. In addition, m-cresol purple sodium salt can be used to stain epithelial cells and proteins.