Biuret chemical formula 3D rendering of Biuret
The Biuret Reagent is one that detects the presence of proteins, short peptides and other compounds with two or more peptide bonds in substances of unknown composition.
It is made of potassium hydroxide (KOH) and cupric sulfate (CuSO4), together with sodium potassium tartrate (KNaC4O6 · 4H2O). The reagent, blue, changes to violet in the presence of proteins, and turns to pink when combined with short chain polypeptides. Potassium Hydroxide does not participate in the reaction, but provides the alkaline medium necessary for it to take place.
A colorimetric method is used in the Biuret assay to determine the protein concentration of a sample by ultraviolet-visible spectroscopy at a wavelength of 540 nm (to detect the Cu ion). Process Bibliography
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