What is the primary purpose of using ninhydrin in fingerprint analysis?

The use of ninhydrin in fingerprint analysis primarily focuses on its ability to develop latent fingerprints on porous surfaces. Ninhydrin reacts with the amino acids that are present in the sweat and other residues left behind by the fingers, producing a colored compound that makes the latent prints visible. This reaction is particularly effective on surfaces such as paper, cardboard, and certain fabrics, where fingerprints may otherwise be difficult to detect.

The chemical process involves ninhydrin binding to the amino acids which results in a color change, generally producing a blue or purple color, enabling investigators to clearly see the pattern of the fingerprints. This property makes ninhydrin a vital reagent in forensic science for enhancing the visibility of prints that would not be seen otherwise.