What is the principle behind the ninhydrin test?

What is the principle behind the ninhydrin test?

Principle of Ninhydrin Test This assay is based on the fact that two molecules of ninhydrin (2, 2- dihydroxyindane-1, 3-dione) react with a free alpha-amino acid to produce a deep purple or blue color known as Ruhemann’s purple.

Which is better test for proteins biuret or ninhydrin?

The Ninhydrin test displayed a minimum level of detection observed by 75% of volunteers (MLD(75)) of 9.25 microg [95% confidence interval (95% CI) 8.6-10.0 microg]. The Biuret test provided better sensitivity, with a MLD(75) of 6.7 microg (95% CI 5.4-8.2 microg).

What are the requirements and result of the ninhydrin test?

Ninhydrin Test: Principle, Requirements, Procedure and Result. Principle: This test is a general test and thus given by all amino acids. This test is due to a reaction between a amino group of free amino acid and ninhydrin.

Why is ninhydrin used in amino acid analysis?

If nitrogen is deprotected, the ninhydrin test turns blue. It is used in the analysis of amino acid in proteins. Most amino acids hydrolyzed and react with ninhydrin with the exception of proline. Some amino acid chains degrade. Hence, a separate analysis is needed in order to identify amino acids that may react or not react with ninhydrin at all.

What does purple mean on a ninhydrin test?

Result and Interpretation of Ninhydrin Test The presence of a purple-colored complex in the tube represents a positive result and indicates the presence of amino acid in the sample. The absence of the complex in the tube represents a negative result and indicates the lack of amino acids in the sample.

Which is the correct formula for ninhydrin in IUPAC?

In this test, ninhydrin (a chemical compound with the formula C 9 H 6 O 4; IUPAC name: 2,2-dihydroxyindane-1,3-dione) is added to a test solution of the analyte. The development of a deep blue colour indicates the presence of ammonia, primary/secondary amines, or amino acids in the analyte.