Effect of detergents and sucrose derivatives on the modified protein determination of Lowry.

The effect on the protein determination method of Lowry, as modified by Hartreee, of widely used detergents (sodium deoxycholate, sodium laurylsulphate, Triton X-100 and Triton WR-1339) and of sugar derivatives often used for preparing concentration gradients (sucrose, dextran, Ficoll and Metrizamide) was examined. Each of the compounds studied gave rise to a coloured product in the test; however, the correlation between concentration and optical density was usually nonlinear. The majority of these substances - especially Ficoll, Metrizamide and dextran - interfere with the procedure even at low concentrations, thus their elimination from the sample before protein determination is inevitable.