What component of a fingerprint does Ninhydrin primarily react with?

Ninhydrin primarily reacts with amino acids, which are organic compounds that serve as the building blocks of proteins. When ninhydrin is applied to a fingerprint, it interacts with the amino acids left behind in the sweat and other residues deposited by the fingers, leading to a color change that indicates their presence. This reaction is particularly useful in forensic science because amino acids are often abundant in latent fingerprints, making it an effective method for developing these impressions for further analysis.

The other options do not accurately reflect the specific component that ninhydrin targets. Fats, while present in skin secretions, do not form a strong reaction with ninhydrin. Water is a solvent and does not react chemically in the same way that ninhydrin reacts with amino acids. Lastly, minerals in the fingerprint residue do not have the same chemical interaction with ninhydrin and are not the primary focus of this reagent. Thus, ninhydrin’s specificity for amino acids makes it an invaluable tool in latent print visualization.