Europium aryl-β-diketone complexes as fluorescent dyes for the detection of cyanoacrylate developed fingerprints on human skin

Abstract

The application of europium luminescence to the visualisation of cyanoacrylate developed finger-prints is reported. Extremely fluorescent europium chelates are produced by the reaction of Eu 3+ ions with aryl-β-diketones. Excitation of the organic ligand occurs at 350 nm for europium tris(thenoyltrifluoroacetone) (TEC) and europium narrow band (10 nm) emission is observed at 614 nm as a result of an intramolecular energy transfer. The europium aryl-β-diketone complexes are transferred into the interior of the polymeric cyanoacrylate from an aqueous methyl ethyl ketone solution. A two phase system is established with methyl ethyl ketone, water and chelate outside the polymer and methyl ethyl ketone and chelate inside. As the print dries the ketone evaporates ‘locking’ the chelate inside the cyanoacrylate. Sufficient TEC is deposited in the polymer so that the print is easily seen under 7 mW/cm 2 of Hg light. Washing away of background contamination does not harm the fluorescent print. Prints deposited on cadaver skin and fumed with cyanoacrylate have been detected with good detail by this method.