Separation of visibly-excited fluorescent components in fingerprint residue by thin-layer chromatography

The use of lasers for the detection of fingermarks is widespread in the for ensic field. Despite this, and the fact that many studies have been conduct ed into the composition of fingermark residue, the components responsible f or the inherent visible fluorescence remain unidentified. Traditionally compositional studies have been performed on sweat, sebum, or skin surface washes, none of which are truly representative of the situati on when a fingerprint is deposited on a surface. In this paper thin-layer c hromatography (TLC) has been performed on sebum-rich fingermarks laid direc tly onto TLC plates and an argon ion laser used to visualize the separated components. It has been found to be a robust and reproducible method for st udying the fluorescent components in fingermark residue and is considered t o be more realistic than other methods of sample preparation as it eliminat es the chances of extraneous matter being extracted from the skin surface. Investigations into the nature of the separated compounds have also been ma de and the results are reported.