Application of dye intercalated bentonite for developing latent fingerprints

Two types of cationic dye, Rhodamine 6G (R6G) and Methylene Blue (MB), intercalated bentonite have been developed to visualize latent fingerprints. The dyes were first absorbed on bentonite particles by an ion exchange process and the particle surface was subsequently modified by phenyltrimethoxysilane (PTMOS). Resulting particles retained incorporated dye with good affinity and their surfaces were rendered organophilic due to the planar aromatic ring of PTMOS grafted on the surface and edges of layered bentonite particles. Such organophilic properties promoted attachment of particles to finger mark residues. Particles were harvested as a powder and applied as a dusting agent using brushes.