What does the biuret test detect?

The biuret test is specifically designed to detect the presence of peptide bonds, which are formed when amino acids link together to create proteins. When proteins are present in a sample, they react with the biuret reagent, resulting in a color change that indicates the presence of peptide bonds. The test relies on the formation of a complex between copper ions in the biuret reagent and the peptide bonds, which turns the solution violet in color.

While the test is used to assess protein concentration indirectly, it is not primarily designed for that purpose. The detection of amino acids is also not correct, as the biuret test does not respond to free amino acids, but rather to the compiled structure of proteins containing peptide bonds. Thus, recognizing that the biochemical principle behind the biuret test involves the interaction with peptide bonds is crucial for understanding its application in laboratory settings.