What component of a fingerprint does Ninhydrin react with?

Ninhydrin specifically reacts with amino acids, which are organic compounds that serve as the building blocks of proteins. When a fingerprint is deposited on a surface and contains sweat, it often has amino acids present in it. When ninhydrin is applied, it undergoes a chemical reaction with these amino acids, leading to the formation of a colored complex, typically a purple-blue hue. This visible reaction allows forensic scientists to effectively visualize latent prints on surfaces, thereby enhancing the ability to analyze and identify individuals based on their fingerprint patterns.

In contrast, proteins, while they contain amino acids, are not the target of the ninhydrin reaction in the context of latent print development. Fats and minerals also do not react with ninhydrin; they require different chemical development techniques to visualize latent prints. Understanding how ninhydrin interacts specifically with amino acids is critical for latent print examiners as it underpins one of the common methods used in fingerprint analysis.