biuret test

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a urea derivative; its presence is detected after addition of sodium hydroxide and copper sulfate solutions by a pinkish-violet color (protein test) or a pink and finally a bluish color (urea test).
biuret reaction the reaction in biuret tests.
biuret test either of the tests done with biuret.

bi·u·ret test

a test for the determination of serum proteins, based on the reaction of an alkaline copper reagent with substances containing two or more peptide bonds to produce a violet-blue color.

biuret test

Etymology: 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.

biuret test

A colourimetric urine test for identifying peptides and proteins using the biuret reagent (sodium hydroxide and copper sulfate).

bi·u·ret re·ac·tion

, biuret test (bī'yŭr-et' rē-ak'shŭn, bī'yŭr-et' test)
The formation of biuret, which gives a violet color because of the reaction of a polypeptide of more than three amino acids with CuSO4 in strongly alkaline solution; used for the detection and quantitation of polypeptides or protein in biologic fluids.
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