Ninhydrin is widely used in forensic science for detecting fingerprints on porous surfaces like paper. It reacts with amino acids present in sweat residues, producing a purple-blue color known as Ruhemann's purple, which makes latent prints visible. In biochemistry, it serves as a reagent to detect and quantify amino acids and proteins, aiding in the analysis of peptide sequences and protein content. Additionally, ninhydrin is employed in chromatography as a visualizing agent to identify amino acids in thin-layer or paper chromatography. Its ability to react with amines also makes it useful in quality control processes for pharmaceuticals and food products, ensuring the absence or presence of specific amino compounds.