Advances in Fingerprint Technology.pdf

Procedure
1. Fill the spray unit with the working ninhydrin solution and spray the
surface containing the latent print from a distance of about 6 in.
2. Allow the solvent to evaporate and then repeat the spraying process.
3. After spraying, the surface can be heated with an infrared lamp or
steam iron for a short period. Be careful not to overheat the surface
and do not allow the heat source to come into direct contact with the
surface.
4. Alternatively, leave the specimen at room temperature until the latent
print fully develops. It may take quite a bit longer to develop prints
at room temperature than it would if the development is heat
enhanced. However, it often yields more satisfactory results.
As just noted in connection with the ninhydrin solution formulation, a
number of latent print investigators have recently focused attention on reformulating
ninhydrin, its analogues, and other chemicals that are commonly
sprayed (such as DFO) in solvents/vehicles other than Freon 113. Freon 113
(CFC 113, 1,1,2-trichlorotrifluoroethane) was included in the “Montreal Protocol”
signed in 1987 which banned CFCs in most of the industrialized
countries because of concerns about the ozone layer. It appears likely that
CFCs will not be available for this purpose. It should be noted that Watling
and Smith 116 and Hewlett, Sears, and Suzuki 117 used heptane as the solvent
because of the resulting reagent’s performance; heptane is extremely flammable.
Margot and Lennard 9 noted that they have substituted mainly petroleum
ether, even though care and attention are necessary because of the
potential fire hazard. Jungbluth 118 explored an industrial solvent called Genesolv
2000 for both ninhydrin and DFO and found it to be satisfactory, and
Hewlett et al. 117,119 found the hydrofluorocarbons (HFCs) HFC4310mee and
HFE7100 to be promising ninhydrin solvents, but not as good overall as the
heptane based formulation.
Marquez described a modified ninhydrin development procedure applicable
to carbonless form documents. 120 Here, the ninhydrin solution was
prepared in ethanol and heptane. Filter paper pieces the size of the document
were saturated with the ninhydrin solution and then allowed to dry. The
document was then sandwiched between the filter papers and heat applied
for 30 min, after which the document was placed in a humid chamber. This
method was said to prevent the ninhydrin solvent from causing running of
the writing on the carbonless document. Pressly described the successful
processing of latent prints on latex gloves using a ninhydrin dipping procedure,
but with no heating. 121 Margot and Lennard said that heat acceleration