Preparation, Characterization, and Application of a Lipophilic Coated Exfoliated Egyptian Blue for Near-Infrared Luminescent Latent Fingermark Detection

A simple technique is described to create nanoscale near-infrared luminescent Egyptian Blue pigment particles with lipophilic surfaces for latent fingermark detection. An exfoliated Egyptian blue powder coated with cetrimonium bromide was prepared using a simple, one-pot process. Particle size and surface coatings were characterized using scanning electron and atomic force microscopies, dynamic light scattering, and infrared and luminescence spectroscopies. This new fingermark dusting powder presented more contrast compared to uncoated Egyptian blue of comparable particle size as well as commercial visible light fluorescent (Blitz Red) and near infrared luminescent (fpNatural1) powders in the detection of aged fingermarks on model surfaces. The coated Egyptian blue pigment presents a cost-effective fingermark dusting powder that reveals high contrast latent fingermarks with simple, inexpensive photography equipment.