01. Universidade Federal Rural de Pernambuco - UFRPE (Sede)
URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/1
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Resultados da Pesquisa
Item Investigação das modificações químicas de biomarcadores de petróleo submetidos a derrames simulados em ambientes aquáticos(2021-12-15) Oliveira, Milton Neto Nascimento de; Santos, Jandyson Machado; http://lattes.cnpq.br/4137257750865101; http://lattes.cnpq.br/4629247582941612The oil industry characterizes a source of risks to the environment. Studies that aim to understand the chemical modification in oil spill situations are gaining greater attention due to recurrent environmental disasters, such as the one that occurred on the coast of Brazil in 2019. The purpose of this study was to apply a laboratory simulation of oil spills in aquatic environments, to evaluate the chemical changes in composition of oils using the technique of gas chromatography coupled to mass spectrometry (GC/MS) and infrared spectroscopy (IR). For the simulations, a homemade system was used that were a chamber with white, blue and ultraviolet lamps, referring to wavelengths like those emitted by solar radiation, where inside was allocated a mixture of oil and seawater 1:80 (m/v), and the oil spill simulation was performed to obtain aliquots of oil at different times of exposure. The oil aliquots were analyzed by GC/MS, in order to obtain a comparative analysis of the initial crude oil (control) and the same oil after the spill exposures, which was possible to evaluate the chemical changes of oil biomarkers and their diagnostic reasons. The chromatograms showed a decrease in the peak areas of the n-alkanes with lower molecular weight in the first hours of exposure to the simulated spill, however, no significant changes were observed in the diagnostic ratios for biomarkers of the sterane and terpane classes, showing that they are classes that do not change chemically. The IR was performed in the spectral range of 600-4000 cm-1, using attenuated total reflectance (ATR). The IR data showed peaks related to the majority chemical composition of crude oils, referring to aliphatic hydrocarbon compounds. It was also possible to identify peaks related to the appearance of new stretching linked to chemical changes associated with the photo-oxidation process that occurred in the spill simulation, referring to peaks for oxygenated compounds, in the region of 1233 cm-1. Thus, the study was able to identify some changes in the chemical composition of crude oils after simulated spills in aquatic environments, as well as to show that the consolidated diagnostic ratios involving terpanes and steranes do not change, and in both cases can be used in studies to track oil spills in environments and/or as data for remediation of environments impacted by spills involving the oil industry.Item Utilização de técnicas analíticas instrumentais voltadas para a datação de tinta de caneta na química forense(2021-12-14) Braga, Kauanny Beatriz do Nascimento; Santos, Jandyson Machado; http://lattes.cnpq.br/4137257750865101; http://lattes.cnpq.br/6073573253074251Forensic chemistry connects science with justice, applying scientific techniques and methodologies that help in finding information and elucidation of crimes committed by identifying different types of chemical compounds, thus facilitating criminal investigations. Among the different areas that make up forensic chemistry, documentoscopy is of great importance. It is responsible for providing historical information of a document, evaluating its veracity for legal purposes, such as in an attempt to date writings with a pen. In our study, simulations were carried out in an aging laboratory for blue ballpoint pen inks, focusing mainly on the Crystal Violet (Basic Violet 3) compound, which is the main chemical constituent of pens. The inks were subjected to a camera with the direct incidence of lamps with emission in the ultraviolet and visible regions, at different exposure times and the analyses were performed by infrared (IR) spectroscopy by Fourier transform with attenuated total reflection mode to assess the degradation of the chemical composition of inks. The IR spectra showed regions with peaks that suggested some interesting changes in the chemical composition after the artificial aging process, for the peaks in 752, 1244, and 1584 cm-1. Thus, the proposal was also used in an attempt to date pen ink for real documents containing writings dated between the years from 1975 to 2017. The data showed similarity with the results found in the simulated aging experiments, where it was possible to notice main-ly that there was a reduction in the absorption band referring to the 1584 cm-1 peak, due to chemical modification related to the C=N bond in the Basic Violet 3 molecule. Furthermore, a divergence between the IR spectra between the artificially aged samples and the real ones, for the peak at 752 cm-1, suggests that there may be more than one degradation mechanism in the paint aging process. Thus, the proposed method demonstrates the potential for performing routine analyses in the field of documentoscopy, for pen ink dating.