Spectral variations for reaction products formed between different amino acids and latent fingermark detection reagents on a range of cellulose-based substrates

Ninhydrin, 1,2-indanedione, 1,2-indanedione-zinc, and l,8-diazafluoren-9- one (DFO) are reagents used worldwide for latent fingermark detection on paper substrates. Although research groups have concentrated on optimization studies and improvements in reagent formulations, mechanistic studies and comparisons against the different amino acid constituents in eccrine secretions are rare in the literature. It is known from studies undertaken in different geographic areas that these reagents produce varied results on different paper substrates under different environmental conditions; however, such observations have not been quantified. In this study, ninhydrin, indanedione, indanedione-zinc, and DFO reagents have been used to enhance deposits of nine major amino acids on three types of cellulose-based media: ashless filter paper, 10% recycled copy paper, and cellulose-coated TLC plates. Absorption and luminescence spectra were recorded for the resulting reaction products. The results provide some insight into the activity of these fingermark detection reagents with respect to the different amino acids present in eccrine deposits.