Fingermark dusting powders are an important tool of forensic practitioners, being a first-choice process for most crime scene investigators. The development of new products is of utmost importance for forensic science. Hydrazones comprise compounds derived from ketones or aldehydes in reaction with hydrazines. These reactions are widely studied in organic chemistry because of the versatility of these compounds in organic synthesis. The study of these reactions leads to the understanding of the nucleophilicity of hydrazines, as well as the electrophilicity of aldehydes and ketones. The present work presents one proposal of experimental organic chemistry, aiming at a new application of this classic class of organic substances in forensic chemistry, specifically as a developer of latent fingermarks due to the variations of the color of the compounds, with spectra ranging in a range from 250 to 500 nm. These compounds were identified by Infrared Spectroscopy, Ultraviolet-Visible Spectroscopy and Mass Spectrometry. The development on glass surfaces demonstrated the potential application of these compounds in everyday life situations.

Natural formulations have attracted great interest of many researchers regarding their use as latent fingermark developers powders due their important characteristics as the presence of natural pigments in these materials that offer a good contrast on the applied surface and also luminescent properties, which facilitates the visualization of minutiae in problematic substrates such as multicolored surfaces. In addition, natural powders present low toxicity, are widely available and economically viable. In this sense, the present work addresses the application of several natural products to enhance fingermarks visualization. The natural products were obtained from various sources such as seaweed, spices as well as other sources such as terrestrial and herbaceous plants. The evaluated powders are composed by compounds as chlorophyll, phycocyanins, curcumins, lawsone, fatty acids, coumarins, flavonoids and terpenes. These powders showed good adhesion to latent fingermarks, with similar or superior efficiency to the available powders on different surfaces with clear visualization of the minutiae. The development of new powders applicable to papiloscopy are extremely important since the conventional available powders, besides being expensive, are imported and within the national context there is a great lack of these revealing materials within forensic investigations by the Federal Police and in laboratories of research.

This work describes a simple and inexpensive flow injection analysis system in which gravity force provides fluid propulsion while needles for insulin administration or metallic wires act as electrodes for amperometric detection. The proposed system was able to demonstrate the influence of several operational parameters on the transient signals. Moreover, this system was successfully used to evaluate both the stoichiometry of Cu2+-EDTA complex and the effect of pH on the kinetics of the reaction between ferricyanide and ascorbic acid. Therefore, the proposed system can be regarded as an efficient and accessible didactic tool for the teaching of FIA principles.