Advances in Fingerprint Technology.pdf

More recently, Almog et al. have synthesized and evaluated a series of
both 4- and 5-aminoninhydrins. 147 Absorption and emission characteristics
of the compounds were determined and part of the evaluation was based on
the reaction of the compounds with alanine in solution. The 5-aminoninhydrins
were superior to the 4-amino compounds. However, the 5-amino compounds
gave significantly slower development than either ninhydrin or
5-methoxyninhydrin. It was noted that the 5-amino compounds might prove
useful as direct fluorigenic reagents for developing latent prints on fluorescent
surfaces that absorb in the 400- to 500-nm range and emit at 550 to 650 nm,
precluding the use of ninhydrin or 5-methoxyninhydrin.
Menzel and Almog have studied the fluorescent properties of the fingerprints
developed by ninhydrin analogues when complexed with zinc chloride.
They found that only benzo[f]ninhydrin complex fluoresced as intensely as
the ninhydrin complex, and its absorption maximum is 530 nm. The neodymium:yttrium
aluminum garnet (Nd:YAG) laser emits light at 532 nm and
is more effective than the argon ion laser, which has emission maxima at
488 nm or 514 nm. 148
Lennard et al. 149 have synthesized methoxy, chloro, bromo, and perinaphtho
derivatives of ninhydrin. They found that fingerprints developed by all
of the derivatives have the same sensitivity as ninhydrin and photoluminescent
complexes that were formed on addition of zinc and cadmium salts.
Almog et al. 150 synthesized 5-methylthio-ninhydrin derivatives and tested
them next to other ninhydrin analogues and DFO. They showed superior
luminescence properties when the reaction product was complexed with zinc.
Cantu et al. 151 compared a series of ninhydrin analogues using a dried amino
acid spot model and found thieno[f]ninhydrin to be superior when complexed
with zinc, thus providing further evidence that the sulfur-containing
ninhydrin analogues exhibit superior luminescence properties when complexed
with zinc.
Ramotowski et al. reported on the effectiveness of a series of 1,2-indanediones
synthesized at the University of Pennsylvania for latent print development.
152 These compounds may be regarded as ninhydrin analogues of a sort.
Overall, the 5,6-dimethoxy-1,2-indanedione was the most effective. 153 The
5,6-dimethyl compound (50 mg) was dissolved in 2 mL methylene chloride
and then diluted with 50 mL methanol. The zinc complex of the reaction
product gave very good luminescence results with test amino acid spots and
with test latent prints. Almog’s group further validated 5,6-dimethoxy-
1,2-indanedione as equal or superior to other ninhydrin analogues and to
DFO. 154,155 Wilkinson 156 presented spectroscopic evidence that alcohols
should be avoided as a solvent for the 1,2-indanedione compounds for latent
print development. Recently, the Almog group reported that computational
design software might be useful in modeling the potential luminescence