Biuret-15N3 is the 15N3 labelled analogue of Biuret (B591500) which is used as a source of non-protein nitrogen in feed for ruminant. It is an impurity of urea based fertilisers as it has a poisonous effect on plants if present in high concentrations. Like peptide bonds, biuret forms violet-colored complexes with copper(II) ion in alkaline solution. This color change response is used to identify and quantify protein concentration (due to peptides present) and is known as biuret test.
