Ninhydrin, Hi-AR/ACS (2,2-dihydroxy-1,3-indanedione, CAS 485-47-2, molecular weight 178.14) is an analytical reagent and ACS grade powder, white to pink to brownish-white, with an FTIR matching the standard pattern and a melting point near 240 C. It is the classic colour reagent for detecting amino acids, peptides and primary amines, producing the characteristic purple Ruhemann colour, and is widely used in chromatography, protein chemistry and forensic latent-print work. Store below 30 C. Packaged as 10 g.