What component does Small Particle Reagent adhere to in the fingerprint deposit?

The Small Particle Reagent (SPR) is designed to adhere specifically to fats within a fingerprint deposit. Fingerprints left on surfaces consist of various substances, including water, oils, fats, and other organic compounds. The fats present in the sebaceous secretions are critical because they help to preserve the fingerprint's structure and make it visible when treated with SPR.

When SPR is applied, it works by binding to those fatty components, creating a distinct contrast that makes the fingerprint more visible against the background surface. This is particularly useful in forensic applications, where faint or difficult-to-see prints need to be enhanced for identification purposes. Therefore, understanding the interaction between the SPR and fatty deposits clarifies its effectiveness as a detection method in latent print analysis.

In contrast, the other options—water, chlorides, and oils—either do not represent the primary target of SPR or are not significant components that the reagent specifically adheres to during the development process. This specificity is what makes SPR a valuable tool in fingerprint analysis.