Ninhydrin 2%, alcoholic, is mainly used in medical diagnostics and scientific laboratories. It is known for its ability to react with amino acids and peptides, which makes it an indispensable tool in protein and amino acid analysis. Ninhydrin (C9H6O4), which is present in the solution, interacts with these molecules, causing a characteristic blue coloration when heated, known as the Ruhemann purple hue.

Ninhydrin's unique chemical property of combining through condensation reactions also allows it to visualize free amines and ammonia. In addition, it can be used in forensics to detect fingerprints because amino acids in dander react to the ninhydrin solution.

Using Ninhydrin 2%, alcoholic, usually results in a visible staining reaction that allows qualitative or quantitative analysis.