biuret test /bī″yo͝oret/ [L, bis + Gk, ouron, urine] , a method for detecting proteins in serum. In alkaline solution, copper sulfate ions react with the peptide bonds of proteins to produce a pink to purple color, called the biuret reaction. The amount of serum protein in a sample solution is estimated by comparing its color with that of a standard solution whose protein concentration is known.
