Method of determination of proteins with Coomassie brilliant blue G 250. II. Influence of pH and inorganic ions

: The influences of pH and inorganic ions on the protein assay method of Bradford were investigated. Absorbance of bovine serum albumine appears to be increasing with the increase of pH. This effect is consistent with the hypothesis of Reissner et al. (1975), that colour change of the stain is a function of hydrogen ion concentration, but acquires statistical significance only for extreme basic pH. Among the tested inorganic ions, only Fe++ and NH4+ shows some interference. These dysadvantages could be corrected by appropriate blanks.