Which chemical reacts with amino acids in fingerprint deposits?

The correct answer is ninhydrin because it is a chemical that specifically reacts with amino acids, which are often present in fingerprint deposits. When ninhydrin is applied to a surface with latent fingerprints, it reacts with the amino acids to form a complex that produces a colored product, typically turning blue or purple. This reaction is essential for the visualization of fingerprints on surfaces that are porous or have absorbed moisture, making it a widely used technique in forensic science for latent print development.

In contrast, Freon 113 is a solvent that was historically used for cleaning and degreasing but does not have a chemical reaction with amino acids. Iodine vapor can develop latent prints on certain surfaces but works through a different mechanism, primarily relying on the interaction with lipids and oils rather than amino acids. Superglue, or cyanoacrylate, is commonly used in fuming to create a visible print through a polymerization process but also does not target amino acids. Each of these chemicals has its specific applications, but ninhydrin is the unique reagent that actively interacts with amino acids in fingerprint residues.