Essay On Particle Reagent

Abstract:-The small particle reagent is essentially a suspension of an insoluble powder in solution of a surfactant by which latent fingerprint on wet surfaces can be developed. SPR is sensitive towards the lipid constituents in the latent fingerprint residues. Adherence of fine particles suspended in a treating solution to the fatty or oily constituents of latent fingerprint residues accordingly may be regarded as a same as methods as powder dusting method. Small particle reagents consisting of suspension of fine particle (Molybdenum disulfide) in detergent the particle adhere to the fatty constituents of latent fingerprint residues. Conventional SPR contains dark grey coloured Molybdenum disulfide particles, suspended in detergent which gives effective result on non-porous surfaces. use of graphite, cobalt oxide, lead oxide, Xerox powder and monastrol blue dye has also been used. The powder suspension is commonly referred to as small-particle reagent (SPR), and the technique is essentially a wet powdering method. The powder

Fluorescent SPR was prepared with the addition of a fluorescing agent, Brilliant Yellow 40 (BY-40) for improving contrast of developed fingerprints on dark or multicoloured background under excitation in blue range of spectrum. BY-40 was mixed with SPR stock solution and was then diluted to a working suspension. SPR stock and working suspension were prepared according to the procedure suggested by the manual of fingerprint detection technique. Prints were placed on various types of multicoloured objects such as multicoloured glossy paper, multicoloured cola cane, black polythene and glass slide. The BY-40 SPR suspension was sprayed on the surface. Developed prints were examined in white light and with the Rofin Polylight 300 watt light source. Excitation was made at 450 nm, 505 nm and 530 nm with observation above 549nm