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1.A new method for enhancement of ninhydrin or 1,8-diazafluoren-9-one (DFO)-treated latent fingerprints on thermal paper will be described. Most thermosensitive surfaces of thermal paper become dark when treated with DFO or ninhydrin petroleum ether (NPB) solution. This effect minimizes contrast between the developed fingerprints and the background. The new method described reduces this dark staining without removing the thermosensitive layer and parts of the developed fingerprints, as occurs with acetone washing. Through the new method, the developed fingerprints appear in sharp lines and high contrast. Extensive tests were performed, leading to an optimized working solution, which charges the paper with a minimum of chemicals, is cheap, and enables a large quantity of papers to be treated in a short time. The working solution contains commercially available, nonvolatile, nitrogenous organic compounds and can be used like the application of NPB solution by dipping.

2.This paper describes the study of the reaction between 1, 8-diazafluoren-9-one (DFO) with the amino acid L-alanine in methyl alcohol. Particular interest was paid to the possible role of the solvent which appears to react with the DFO to form a hemiketal that is the reactive species. A potential reaction pathway is proposed based on the current data collected. The reaction intermediates and products were identified by a variety of spectroscopic methods including mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, and X-ray crystallography.