Advances in Fingerprint Technology.pdf

and certain nonreactive surface materials. Numerous compounds have been
reported as potential substitutes for ninhydrin in the detection of latent
fingerprints. They can be divided into two categories: reagents for amino
acid detection and ninhydrin analogues. This area has been thoroughly
reviewed by Almog 133 and is the subject of Chapter 5 of this volume.
Reagents for Detection of Amino Acids
In the 1970s and 1980s, fluorescamine, 134 o-phthalaldehyde 135 and NBDchloride
(7-chloro-4-nitrobenzo-2-oxa-1,3-diazole), 136,137 NBD-fluoride
(7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole) (Criminal Investigation Bureau,
Taiwan, Republic of China, personal communication, 1989), and dansyl
chloride 138 had been suggested as substitute reagents for ninhydrin. These
reagents react with amino acids in the fingerprint residues to produce fluorescent
products that render the latent print pattern visible. 139 Studies have
shown that these reagents not only have a greater sensitivity than ninhydrin
but also work well for the detection of latent fingerprints on multicolored
materials. An additional advantage of the treatment of latent prints with
fluorescamine, o-phthalaldehyde and NBD-chloride (NBD-Cl) is that they
can subsequently be further enhanced with laser light, xenon arc light, or
other light sources. 140 The principal disadvantages of these fluorigenic
reagents are that they are not too stable in solution and sometimes produce
interfering background luminescence. The procedures for preparing these
reagents are as follows:
Fluorescamine reagent
Fluorescamine 20 mg
Acetone 100 mL
20% triethylamine-methylene chloride solution 4 mL
Note: Fluorescamine is dissolved in acetone, the 20% triethylamine-methylene chloride
solution is added, and the pH is then adjusted to 9 to 11.
o-Phthalaldehyde reagent
Boric acid 2.5 g
Water 95 mL
4 N KOH See below
30% Brij 35 solution 0.3 mL
2-Mercaptoethanol 0.2 mL
o-Phthalaldehyde 0.5 g
Methanol 1 mL