Functionalization of pyrrole derivatives as a way to improve their solubility in aqueous medium for applying in latent fingerprints development

Abstract Latent fingerprints (LFPs) play an important rule for criminal investigations regarding to the identification and connection of an individual to a crime scene. Herein, we report a non-destructive method for LFPs development based on the electropolymerization of pyrrole derivatives modified with water-soluble groups on stainless steel surfaces containing fingerprint residues. The polymers, namely P1, P2, P3 and P4, and a copolymer of 4 with 3,4-ethylenedioxythiophene P(4-co-EDOT) were electrodeposited by oxidation of the monomers in aqueous LiClO4 by applying potentials (E) of 1.25–1.7 V vs. Ag/AgCl or current density (j) of 5.0–10 mA cm−2 for 15–240 s. The quality of the developed fingerprint images was verified by Scanning Electron Microscopy, the Griaule Forensic Fingerprint® software and the Bandey classification system. It was possible to observe the enhancement of the visual contrast between the surface and the fingerprint residues, providing high quality images of the developed fingerprints.