Evaluation of Indanedione Application Methods for Fingermark Detection on Paper: Conventional Treatment, Vacuum Development, and Dry-Transfer.

1,2-Indanedione is considered the most sensitive amino acid reagent currently available for routine use as a fingermark detection technique on porous substrates. The method is generally applied by treating items with a solution of the reagent, followed by the application of heat to accelerate the reaction. Despite the high sensitivity demonstrated by this technique, the use of organic solvents and heat can be problematic for some substrates. For example, polar solvents and heat will darken thermal printer paper. Polar solvents will also diffuse writing inks on documents and may also remove other forensic traces such as explosive and illicit drug residues. The solvent-free application of amino acid reagents has been investigated by a number of research groups as a means of overcoming such issues. Examples include vacuum sublimation (low-pressure vaporization) and "dry-transfer" methods. For the latter, items to be treated are sandwiched between sheets of reagent-impregnated paper. Solventless methods can alleviate the need for the storage and use of large volumes of potentially hazardous solvents, including solvents that are being phased out because of their global warming potential. In this study, a method for applying indanedione under vacuum using a commercially available vacuum oven was optimized and applied to treat fingermarks on a range of substrates. The results were compared against those obtained using conventional and dry-transfer techniques. Although a vacuum method was found to be feasible, it was generally outperformed by conventional indanedione treatment. However, encouraging results were obtained on some nonporous surfaces, and this shows promise for future investigation. [ABSTRACT FROM AUTHOR]