Advances in Fingerprint Technology.pdf

Other Dyes and Dye Mixtures. Several other dyes have been used for the
post-treatment of cyanoacrylate-developed fingerprints. These include
Rhodamine 6G (R6G), basic yellow 40 (BY40), basic red 28 (BR28), and
styryl 7 (S7). Mazzella and Leonard 85 looked at Rhodamine 6G, basic yellow
40, basic red 28 and styryl 7 separately and in various combinations. Formulations
were: for R6G, 20 mg R6G in 60 mL propanol and 40 mL acetonitrile
stock, and 5 mL of this stock to 100 mL petroleum ether for working
solution; for BY40, 100 mg in 60 mL propanol and 40 mL acetonitrile stock,
and 5 mL of this stock to 100 mL petroleum ether for working solution; for
BR28, 200 mg BR28 in 60 mL propanol and 40 mL acetonitrile stock, and
5 mL of this stock to 100 mL petroleum ether for working solution; and for
styryl 7, 100 mg styryl 7 as for the others. Dye mixtures were prepared as:
for BY40 + BR28, 3 mL BY40 stock and 2 mL BR28 stock in final volume of
100 mL petroleum ether; for BR28 + S7, 3 mL BR28 stock and 2 mL S7 stock
in final volume of 100 mL petroleum ether; and for BY40 + BR28 + S7, 2 mL
BY40 stock + 2 mL BR28 stock and 2 mL S7 stock to a final volume of 100 mL
with petroleum ether. These formulations appear in Margot and Lennard 9
as well. BR28 was an excellent enhancement dye. S7 was found not to be
especially stable. Olenik 86 described a simple three-dye blend consisting of
Ardrox P133D, R6G, and BY40: 1 L of the solution was made by adding 1 g
BY40, 0.1 g R6G, and 8 mL Ardrox to 940 mL isopropanol or denatured ethanol.
Adding an additional 50 mL acetonitrile enhanced the luminescence effects.
Various different dyes are used to post-treat cyanoacrylate-developed prints
because they have different absorption and emission maxima and thus offer
versatility in enhancing latent fingerprints on various types of surfaces that can
themselves be multicolored and have varying luminescence characteristics. Dye
mixtures increase versatility through intermolecular energy transfers that enable
the examiner to take advantage of one dye’s absorption maximum while monitoring
luminescence at another dye’s emission wavelength.
Cummings, Hollars, and Trozzi 87 did similar studies on a number of dye
mixtures for the treatment of cyanoacrylate-developed latents. Some of their
stock and working solution recipes differ slightly from those above. Two
mixtures are of interest. So-called RAM is Rhodamine 6G, Ardrox, and MBD.
MBD is 7-(p-methoxybenzylamino)-4-nitrobenz-2-oxa-1,3-diazole. Stock
solutions are
R6G: 100 mg in 100 mL methanol
MBD: 100 mg in 100 mL acetone
RAM is then made using 3 mL R6G stock, 2 mL Ardrox P133D, and 7 mL
MBD stock in 20 mL methanol, 10 mL isopropanol, 8 mL acetonitrile, and