Chromatography and paper electrophoresis of sulphonphthalein dyes

TWO of the sulphonphthalein dyes, bromophenol blue1 and bromocresol green2, have been used widely for the detection of protein after electrophoresis on filter paper. The uptake of bromocresol green by protein under these conditions has been studied recently by Franglen and Martin3. Extending this work, the purity of other sulphonphthalein dyes has been investigated with paper chromatography and filter paper electrophoresis; the methods used and the results obtained are described below.