Criticism of the use of Coomassie Brilliant Blue G-250 for the quantitative determination of proteins.

The quantitative determination of proteins in biological fluids, using Coomassie Brilliant Blue G-250, was evaluated. Compared with the biuret method, the Coomassie Blue G-250 method needs a much shorter time for analysis and has a greater sensitivity. The sensitivity of the dye for albumin is significantly greater than for globulins. The standard curves for the biuret method are more linear than those for the Coomassie Brilliant Blue G-250 method. The Coomassie Brilliant Blue G-250 method produces a precipitate, which sticks to the walls of the cuvet and results in an intolerable carry-over. Therefore, the use of the Coomassie Brilliant Blue G-250 method for the quantitative determination of proteins in urine and serum is not recommended.