Which chemical is used to enhance fingerprints on paper surfaces?

Ninhydrin is the chemical that is widely recognized for enhancing latent fingerprints on porous surfaces, particularly paper. When ninhydrin is applied to a surface, it reacts with amino acids that are present in the sweat left behind by fingers. This reaction produces a colored compound, typically a blue-purple hue, which makes the fingerprints visible. The use of ninhydrin is particularly effective because it can visualize fingerprints that may not be otherwise apparent, especially on textured or highly absorbent surfaces like paper.

Other options are not suitable for fingerprint enhancement on paper surfaces. For example, ammonia is typically used for cleaning or in chemical reactions but does not react in a way that would reveal fingerprint residues. Phenolphthalein is primarily used in chemical tests related to pH levels and is not effective for developing fingerprints. Chalk, while an everyday material, does not interact with fingerprint residues in a manner that would make them visible. Thus, ninhydrin stands out as the best choice for enhancing fingerprints on paper, demonstrating its importance in forensic analysis.