Protein assay is the determination of concentration or total level of protein in a solution.There are various protein assays employed like bradford assay and lowry assay

Bradford protein assay is a very quick way of testing for proteins in solutions. However, presence of detergents in the solution being investigated renders this test inapplicable.

non-destructive

Benedict's reagent is not typically used to find proteins. It is commonly used to test for the presence of reducing sugars, such as glucose. To determine protein concentration, methods like the Bradford assay or the Lowry assay are more commonly used.

The Bradford reagent (Coomassie) is commonly used to detect if a sample contains protein. Coomassie will react with aromatic amino acids (phenylalanine, tyrosine and tryptophan) to turn from a dull red color to a bright blue color. This assay is dependant on the amount of aromatic amino acids present, but works well as a "quick and dirty" indicator of the presence of a protein. The bicinchonic acid assay (BCA assay), while more expensive than the Bradford assay, more accurately detects the presence of the peptide bond present in proteins, so it can be used to not only detect proteins which lack aromatic amino acid residues, but also can be used to more accurately determine the concentration of protein in a sample as not all proteins have the same amount of aromatic amino acids.