Doutorado em Química (IQ)

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Análise computacional da solvatação do diclofenaco e interações da melatonina com radical hidroxila: abordagens via dinâmica molecular e teoria do funcional da densidade
(Universidade Federal de Goiás, 2024-11-14) Rodrigues, Allane Catharina Carvalhaes; Oliveira, Heibbe Cristhian Benedito de; http://lattes.cnpq.br/5995553993631378; Oliveira, Heibbe Cristhian Benedito de; Perez, Caridad Noda; Borges, Leonardo Luiz; Gargano, Ricardo; Lima, Igo Torres
Computational chemistry represents an understanding of chemistry as the manifestation of the behavior of atoms and molecules. This active research field, spanning over a decade, employs mathematical techniques and algorithms to model and simulate chemical influences. The application of computational chemistry is crucial in material design, drug development, and the comprehension of biological processes. Analyzing solute-solvent interactions underscores the importance of physicochemical properties in chemical research, whereas the investigation of free radical elimination is essential for physiological balance. Within this context, the proposed study aims to comprehend the mechanisms of hydroxyl radical removal by melatonin and evaluate the aqueous solvation process of diclofenac through molecular modeling, employing Car-Parrinello and Born-Oppenheimer molecular dynamics, in addition to Density Functional Theory. Results from the dynamics of reactions between the •OH radical and melatonin provide a detailed understanding of various involved conditions, emphasizing the crucial influence of variables such as speed, temperature, and attack direction. The reaction with the hydrogen bonded to the nitrogen of the indole group (called H22) is the more favorable. Energy profiles and rate constants support H22 as the most likely path, providing comprehensive insights into the kinetic and thermodynamic characteristics of the interactions. Our findings regarding diclofenac solubility in water highlight the formation of important intermolecular hydrogen bonds between the atoms of diclofenac with water molecules (OH⋯Owater and CO⋯Hwater). The OH⋯Owater bond is exceptionally strong, similar a covalent bond. Additionally, we observe intramolecular hydrogen bonds in the diclofenac molecule (NH⋯OH e NH⋯Cl) and weaker interactions involving CH⋯Cl. Remarkably, diclofenac protonation contributes to molecular rigidity, hindering future hydrogen bonds with adjacent water molecules, directly impacting molecule solubility. Advancements in this field promise to enrich fundamental chemistry understanding and drive practical advancements in various areas, such as pharmacology, molecular biology, and industrial chemistry.
Aplicação da tecnologia supercrítica no tratamento de resíduos plásticos presentes em amostras de água
(Universidade Federal de Goiás, 2023-12-21) Viana , Júlio Cezar Vieira; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Montel, Adão Lincon Bezerra; Silva, Donizete Xavier da; Oliveira, Heibbe Cristhian Benedito de; Brito, Nubia Natalia de
Phthalic acid esters (PAEs) and bisphenol A (BPA) are plastic waste classified as emerging organic contaminants that can harm biota and human health. These residues arise as a result of the fragmentation of plastics into their monomers or the leaching of compounds used as plasticizers, such as BPA and DEP. In addition to contaminants of emerging concern, these compounds are also classified as endocrine disruptors (EDCs), interacting with estrogen receptors and causing harm to human health and the environment. Even with the availability of physical and chemical wastewater treatment methods, classical treatment methods for these compounds have proven not to be efficient in removing these refractory compounds. Therefore, the objective of this work was to use supercritical water oxidation (OASC) technology to investigate the degradation of BPA and DEP plastic waste in aqueous samples. The variables flow rate, temperature, concentration of oxidizing agent (H2O2) and homogeneous and heterogeneous catalyst, such as Cu(NO3)2 and metallic copper wire, respectively were used as parameters for the tests. Metallic copper was also used in the form of a wire together with H2O2. After treatment using OASC Total organic carbon (TOC) removal efficiencies were found to increase linearly with increasing temperature in the range of 400°C to 700°C for all tests with BPA and DEP. For all tests carried out, the best efficiency in removing total organic carbon (TOC) for BPA was achieved at a temperature of 700°C, oxidant concentration of 60 mM and flow rate of 10 mL.min-1 , reaching 91% of removal. For DEP, the best removal efficiency was achieved at a temperature of 700°C, oxidant concentration of 23 mM and flow rate of 10 mL.min-1, achieving 85% removal. Gas chromatography analysis was carried out for the gaseous components and revealed the presence of hydrogen, carbon dioxide, ethane, ethylene, methane and carbon monoxide gases. The analysis of the liquid fraction for BPA samples in the best treatment condition was carried out using liquid chromatography coupled to mass spectrometry and revealed the presence of the intermediate 2-phenyl2-propanol as the main degradation product. The liquid fraction for DEP samples in the best treatment condition was performed by gas chromatography coupled to mass spectrometry and revealed the presence of aliphatic chain hydrocarbons, such as decosane, triacontane, tetracosane and eicosane as the main degradation products. Therefore, the use of supercritical technology proved to be an efficient method for treating aqueous samples containing BPA and DEP.
Aplicações da cromatografia líquida e espectrometria de massas na análise de contaminantes em amostras de leite bovino e arroz para fins de controle de qualidade e segurança em alimentos
(Universidade Federal de Goiás, 2024-03-28) Soares, Daniel de Almeida; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Rezende, Cintia Silva Minafra e; Lima, Leomir Aires Silva de; Alves, Maria Isabel Ribeiro; Brito, Nubia Natalia De
The present study uses liquid chromatography and mass spectrometry approaches as tools for identifying and quantifying contaminants in foods, such as rice and bovine milk. For the sake of comprehension, this study is divided into four stages: 1) Development of an LC-MS methodology for quantifying the antibiotic ceftiofur in bovine milk samples; 2) Determination of bisphenols (A and S) in long-life milk and its respective packaging by Paper Spray Ionization (PSI-MS); 3) Development of a methodology for determining herbicides in rice (Oryza sativa) samples using the miniaturized hollow fiber liquid phase microextraction sample preparation technique (HF-LPME) with electrospray ionization analysis (ESI-MS); 4) Chemometric analysis comparing rice samples contaminated with fungicides and not contaminated from direct analysis by ESI-MS. In step 1, to determine ceftiofur in milk samples, a liquidliquid extraction (ELL) method was developed followed by analysis of the extracts by LC-MS. The main variables associated with the extraction process were optimized and the figures of merit: linearity, limit of detection and quantification (LOD and LOQ), precision and recovery were evaluated. The method presented LOQ 0.80 ng.mL-1 , inter-day precision of less than 7.3% and recovery greater than 94%. Milk samples obtained from cows subjected to antibiotic application were analyzed for the purpose of evaluating the antibiotic elimination profile in the milk samples. In part 2, it was possible to develop a rapid method for analyzing bisphenols (BPA and BPS) in longlife milk samples and their respective packaging using ambient mass spectrometry using the PSI-MS technique. The method was optimized and the figures of merit linearity, precision, accuracy, LOQ and LOD were evaluated, all of which were within the parameters required by national legislation. The bisphenols under study were detected in all samples (packaging and milk) and in only one sample the BPA content was above 10 ng.mL-1 (maximum residue limit) and for BPS the majority of samples presented levels above the same concentration. In milk, a content of up to 150 ng.mL1 for BPA and an average content of 60 ng.mL-1 for BPS was obtained. The results of this study were published in the journal Food Chemistry (qualis A1). In chapter 3, the use of the miniaturized HF-LPME sample preparation technique followed by ESI ionization mass spectrometry analysis for the determination of herbicides in rice is presented. The main parameters relating to the sample preparation method were optimized, with the use of a two-phase system resulting in shorter extraction times. However, in a three-phase system, with the donor phase at pH 1.7 and the acceptor phase at pH 12, extraction was favored for all analytes. The ionic strength was evaluated by adding salt to the donor solution and did not favor extraction. Therefore, the three-phase system presented a better response to the analytes and the method should have its figures of merit evaluated using the optimized HF-LPME/ESI-MS method. The fourth chapter presents a metabolomic analysis followed by chemometric treatment of data obtained by ESI-MS analysis on rice extract samples using positive and negative modes. A comparison of samples was carried out in 4 different matrices (rice husk, grain with husk, polished grain without husk and unpolished grain without husk). The samples evaluated were divided into two groups: contaminated with fungicides and not contaminated. The data obtained made it possible to separate them into classes using treatments using principal component analysis (PCA). In ESI(-) mode, the data were better explained by PCA Without normalization (89.1%) and also by Quantile Normalization (90%). The negative mode better explains the dissimilarity between the contaminated and uncontaminated rice groups.
Sensores miniaturizados para COVID-19 e paracetamol: uma abordagem simples e de baixo-custo
(Universidade Federal de Goiás, 2024-10-09) Moreira, Nikaele Sousa; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Souza , Endler Marcel Borges de; Pedrino, Gustavo Rodrigues; Meloni, Gabriel Negrão; Chaves, Andrea Rodrigues
This work describes the development of miniaturized sensors on accessible and low-cost substrates to detect the spike protein (S) of the SARS-CoV-2 virus and paracetamol in whiskey samples. Protein S is a marker associated with COVID-19, which is present on the external part of the virus and has an affinity with the human angiotensin-converting enzyme 2 (hACE2), allowing the infection of human cells. Therefore, its detection is of great importance for an early diagnosis of the disease. In this context, polyester microplates were developed for the colorimetric detection of this protein in biological samples based on a direct ELISA assay for rapid detection and with less use of reagents, in addition to good clinical accuracy. A linear range was obtained in protein S concentrations of 0-10 μg mL-1, with a coefficient of determination (R2) equal to 0.991 and a limit of detection 0.44 μg mL-1. The proposed methodology revealed satisfactory intraplate and interplate repeatability with standard deviation values below 7.7%. Thirty-seven saliva and swab samples from positive and negative patients were evaluated for the presence of the virus. The results were consistent with the RT-PCR method, showing 100% sensitivity and 85.71% specificity for saliva samples. For nasopharyngeal samples, sensitivity was 90% and specificity was 100%. In addition, it revealed diagnostic accuracy above 94%, indicating that the proposed method can predict more than 94% of the samples correctly. Adulteration of whiskey is a common practice in nightclubs due to the high cost of these original drinks. Counterfeiters often add medications or pharmaceuticals to mask the effects of a hangover, for example, paracetamol, as it is an over-the-counter analgesic indicated for the treatment of headaches. Therefore, distance-based detection of paracetamol in whiskey samples using a paper-based microfluidic analytical device (μPAD) is imperative since the use of paper substrate offers excellent benefits, such as accessibility, portability, and the ability to detect paracetamol without expensive instrumentation. Optimal detection conditions were achieved by introducing 5 μL of a mixture containing 7.5 mmol L-1 of Fe(III) and K3[Fe(CN)6] into the detection zone, together with 12 μL of whiskey samples into the sample zone. The method showed linear behavior in the 15 to 120 mg L-1 concentration range, with R2 equal to 0.998. Paracetamol was quantified in spiked samples using the proposed method, and the results were compared with those of a spectrometric method. No significant differences were observed at the 95% confidence level. The method determined approximately 1 drop of the drug paracetamol of 200 mg mL-1 in 1 L of solution, demonstrating excellent sensitivity. Therefore, the proposed methods are alternatives for practical, simple and economical analyses and reduce the consumption of samples, reagents and waste. Then, they have great potential to be used in the field for clinical applications in diagnosing COVID-19 and forensic applications for detecting paracetamol in beverages.
Síntese de tri-heterociclos pentadienos e estudo de suas propriedades luminescentes
(Universidade Federal de Goiás, 2023-05-09) Matos, Gabriela Ferreira; Kato, Lucilia; http://lattes.cnpq.br/1362891438631386; Kato, Lucilia; Coelho, Felipe Lange; Barros, Olga Soares do Rego; Gonçalves, Pablo José; Santos Neto, José Sebastião dos
This study presents the synthesis of diois (1-4(a-h) and 5, Scheme 1), building blocks commonly used in designing and preparing heteroporphyrins. The synthesis of compounds 1 and 2 has been largely reported in the literature. On the other hand, there are few or no examples of synthetic routes for chalcogen-heteroaryl-substituted compounds such as 3 and 4 (Scheme 1), which constitutes a great challenge. Among the obtained products, thirty-seven molecules are new: five diols, thirty triheteropentadienylmethanes and two porphyrins. Chemical and structural characterization of the compounds 1-4(a-h), 5a and 6 were confirmed through a variety of analytical and spectroscopic techniques: High-Resolution Mass Spectrometry (HRMS), Nuclear Magnetic Resonance (NMR) by 1D and 2D, IR and UV spectroscopy. In addition, X-ray quality single-crystals of 3a allowed the determination of its relative stereochemistry as being (-)-RR-2,5-bis((4-methoxyphenyl)(thiophen-2yl)methyl)thiophene or (-)-SS-2,5-bis((4-methoxyphenyl)(thiophen-2-yl)methyl)thiophene. Unexpected fluorescence emission was observed when compounds triheteropentadienylmethanes were exposed to UV radiation, as shown in Figure 1. The photophysical studies of compounds 2a and 3a revealed a similar absorption profile, with the absorption bands in the violet-to-blue region (between 440-470 nm). Moreover, neither the distinct solvents (ACN, Dioxane, EtOH and CH2Cl2) nor the aryl-substituents (R, Scheme 1) nor the heteroatom (X, Scheme 1) affect significantly the HOMO-LUMO transition energy. In 2a, there is a dependence of the emission wavelength with the excitation wavelength. This fact may indicate that these compounds are examples of molecules exhibiting the non-traditional intrinsic luminescence phenomena.
Novas abordagens para determinação de melatonina e metabólitos em leite materno e aplicação da metabolômica para fins de diferenciação de cultivares de alface
(Universidade Federal de Goiás, 2024-09-11) Machado, Lucas Santos; Roque, Jussara Valente; http://lattes.cnpq.br/7154037221725381; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Bottoli, Carla Beatriz Grespan; Silva, Bruno José Gonçalves da; Faria, Anízio Márcio de; Sgobbi, Lívia Flório
In analytical chemistry, there is a constant search for methodologies that require less cost and analysis time, but at the same time offer precision and accuracy. In this sense, various methodologies and technologies have been evaluated, among which we can highlight those that employ miniaturized sample preparation techniques and those that use ambient ionization sources for mass spectrometry. This thesis is divided into two chapters presenting the potential of modern sample preparation techniques for liquid chromatography analysis and ambient mass spectrometry analysis. The first chapter describes the use of disposable pipette extraction, utilizing a sorbent phase based on molecularly imprinted polymers (DPX-MIP), for the determination of melatonin and its metabolites (AFMK and AMK) in breast milk by liquid chromatography coupled with mass spectrometry (LC-MS). Different MIPs were synthesized and evaluated for their selectivity in analyzing melatonin and its metabolites, experimentally obtained results were compared with molecular simulation data, showing consistency between the theoretical physicochemical parameters and the experimental data. The application of DPX-MIP in conjunction with LC-MS enabled the development of a method for determining melatonin and its metabolites in breast milk, with recovery values ranging from 87-111% and precision between 2-13%, analysis of patient samples produced values consistent with those reported in the literature. The second chapter explores the application of the paper spray ionization mass spectrometry (PSI-MS) technique to study the metabolomics of lettuce cultivars and the potential differentiation according to their cultivation method and variety. PSI-MS, an ambient ionization technique, uses chromatographic paper as a substrate for the sample ionization process. In this study, lettuce samples were successfully differentiated according to variety and cultivation method through the application of chemometric tools (PARAFAC, PCA, PLS-DA, and OPSDA), identifying 36 metabolites responsible for this differentiation, with choline, mannose, and citric acid being the most influential. Additionally, green chemistry metrics, such as AGREEprep and AGREE, were applied to assess the sustainability of the developed methodologies. The results confirmed that DPX-MIP and PSI-MS are more sustainable, offering appropriate analytical performance with shorter analysis times and generating low volumes of chemical waste
Manufatura aditiva circular: utilizando e reciclando materiais termoplásticos para desenvolver sensores analíticos
(Universidade Federal de Goiás, 2024-02-05) Silva Neto, Habdias de Araujo; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Carrilho, Emanuel; Muñoz, Rodrigo Alejandro Abarza; Janegitz, Bruno Campos; Chaves, Andréa Rodrigues
Additive printing technologies have emerged as powerful tools for the development of portable analytical instrumentation including electrochemical sensors. Before using the device, pre-treatment methods are required to improve the electrochemical performance. Additionally, the additive printing method used thermoplastic polymers that can be harmful to the environment compartments. In this report, we successfully developed five different strategies to manufacture 3D-printed electrodes and have also introduced an initiative for recycling thermoplastic materials in order to create electrodes on paper substrate, contributing to the circular economy. The ecological impact of each proposed method was evaluated also. An activation process was performed by using Fenton's reagents, H2O2 (15%, v/v) and Fe (10 mg L-1 ) in the presence of ultraviolet radiation (5 min), followed by an electrochemical oxidation step in the presence of acetic acid (1.8 V vs C for 200 s). The proposed activation method has used non-toxic reagents and showed excellent improvement in the electrochemical responses with long-term stability (~ 2 months). The manufactured 3D-printed electrodes have exhibited suitable values of limit of detection (at µmol L-1 levels) for different analytes, including metals such as Cd(II) (0.009; 1.01 µg L-1 ) and Pb(II) (0.006; 1.24 µg L-1 ), midazolam maleate (0.54) , uric acid (0.71), adrenaline (0.61), S-nitroso-cysteine (4.1) and folic acid (5.1). In addition, the analytical methodologies described here also demonstrated an excellent ecological profile according to the 12 principles of Green Analytical Chemistry.
Implantação das técnicas espectroscópicas de Laser FlashFotólise e de fosforescência para estudos fotofísicos de sistemas porfirínicos e suas interações com biomoléculas e nanoestruturas
(Universidade Federal de Goiás, 2023-12-14) Ducas, Eli Silveira Alves; Gonçalves, Pablo José; http://lattes.cnpq.br/0515343409614452; Gonçalves, Pablo José; Coelho , Felipe Lange; Gomes, Danielle Cangussu de Castro; Lopes, Jefferson Marcio Sanches; Patrocínio, Antônio Otávio de Toledo
The photophysical characterization allows the assessment of processes following the phenomenon of light absorption, which is of interest for various applications, both in the field of materials chemistry and in photomedicine. This work aimed at the photophysical characterization of potential porphyrinic photosensitizers and their interaction with biomolecular systems and nanostructures. To achieve this, the spectroscopic techniques of Transient Absorption (or Laser Flash-Photolysis) and a Spectrophosphorimeter were implemented, and their usage protocols were established. With these techniques in operation, an alternative method for determining the triplet state formation yield and obtaining the singlet oxygen formation yield was proposed, fundamental properties for the characterization of photosensitizers. It was possible to investigate the interaction of water-soluble porphyrins with bovine serum albumin and verify that this interaction affects the triplet states lifetimes and singlet oxygen yields. These parameters were strongly influenced by the presence of oxygen and the porphyrin's location at the interaction sites in the protein structure. Another study conducted was the interaction of cationic porphyrins with manganese ferrite (FeMn2O4) anionic ferrofluids in which the interaction leads to the suppression of fluorescence and singlet oxygen (1O2) generation of the photosensitizers. Interestingly, this interaction is not predominantly governed by electrostatic interactions but mainly through chemsorptives and physisorptives interactions. Additionally, it was demonstrated that photothermal heating breaks the interaction with the nanostructure, restoring the photophysical properties of the photosensitizer, making this system a multifunctional nanostructure with luminescent and theranostics properties.
Calixarenos como plataforma de luminóforos e de co-cristalização com nutracêuticos
(Universidade Federal de Goiás, 2024-08-15) Alvarenga, Meiry Edivirges; Martins, Felipe Terra; http://lattes.cnpq.br/0466799995060671; Martins, Felipe Terra; Gomes, Danielle Cangussu De Castro; Doriguetto, Antonio Carlos; Araújo Neto, João Honorato de; Santos Júnior, Sauli Dos
Calixarenes are notable macrocyclic compounds characterized by a variable number of phenolic units linked by methylene bridges. They possess a series of advantageous features, making them an ideal choice for diverse applications. Their ease of large-scale production from low-cost precursors, coupled with their chemical and thermal stability, as well as the ease of functionalization, elevate calixarenes to the status of highly versatile platforms. They can be utilized in the development of a broad range of materials with potential applications in technological and pharmacological areas. Based on the host-guest properties of calixarenes and the high efficiency of aminopyrazine as a blue light emitter, this research focused on the investigation of two calixarene-pyrazinamide hybrids. The primary goal was to combine hosting capabilities and light emission in a single molecular structure. Two compounds yielded three luminescent crystalline forms, whose structures and optical properties could be correlated. One of them crystallized in two forms, non-solvated and a DMF solvate, while the other, without t-butyl substitutions, formed three conformers with DMF. Variations in molecular substitution affected the conformation of the structures, influencing the coplanarity and conformational profile of the phenolic rings. Under an excitation of 388 nm, both emitted light in the 400-550 nm range, peaking at around 500 nm, but with low quantum efficiency. The low efficiency was attributed to the presence of DMF and π...π stacking interactions. Another aim of this research was to explore the use of calix[4]tube in forming cocrystals with resveratrol, an active nutraceutical known for its potential antibacterial, antioxidant, antiinflammatory, and anticarcinogenic benefits, yet with low aqueous solubility. This work represents the first successful attempt to form a neutral-state resveratrol cocrystal, doubling its water solubility. In summary, this study signifies a significant advancement in using calixarenes as molecular bases for luminophores and in the crystallization of the nutraceutical resveratrol. The employed process proved commercially viable, underlining the immense potential of these methods for future applications in technological and pharmaceutical fields. Therefore, the research focuses on the synthesis of calixarene hybrids with light-emitting properties and the development of cocrystals to enhance the solubility of pharmaceutical compounds, demonstrating the versatility of calixarenes in various areas of chemistry.
Sistemas eletroquímicos - novas abordagens para detecção simultânea e aplicações vestíveis
(Universidade Federal de Goiás, 2024-08-30) Romanholo, Pedro Victor Valadares; Sgobbi, Lívia Flório; http://lattes.cnpq.br/0051559038460460; Sgobbi, Lívia Flório; Martins, Paulo Roberto; Jost, Cristiane Luísa; Galli, Andressa; Madurro, João Marcos
This work presents the fabrication methods and the application of two electrochemical systems. The frst one, named yin-yang method, comprises the development of a novel approach for the simultaneous detection of two solvent incompatible molecules, ascorbic acid (vitamin C), and cholecalciferol (vitamin D3). For that end, two electrochemical cells were arranged in a parallel array, resulting in an analytical method capable of simultaneously measuring the output signal of both analytes in a single run. The main goal of this method lies on the possibility of bypassing the analytical limitations present when both analytes are prepared in a single medium, since vitamin C is readily soluble in water but vitamin D3 hardly solubilizes in the same concentration range. Due to the solubilization impairment, the electrochemical output presents with low resolution when both vitamins are collectively analyzed in a single medium, which also impacts the detection since the electrochemical potential shifts considerably. Results showed that the yin-yang method is reliable, may avoid the use of multichannel potentiostats, and might improve analytical parameters. The second system is presented as a wearable paper-based electrochemical platform employed for the continuous monitoring of sweat glucose levels. The device is fabricated with an iontophoretic stage through which sweat stimulating molecules are delivered across the skin to achieve higher fuid fow-rate, while also employing polyacrylamide gels capable of enhancing osmotic pressure to further increase sweat production. The sensor operates by wicking the biofuid directly from skin through a paper patch, which works as substrate for a glucose oxidase modifed electrode to detect changing levels of glucose. Results showed that the device allows the use for extended periods of time by an individual, displaying matching behavior with that of commercial devices. The output signal stability and resolution are shown to be fow-rate dependent and are infuenced by the individual sweat production profle
Propriedades fotofísicas de filmes multicamadas de perovskita livre de chumbo e compostos eletroluminescentes
(Universidade Federal de Goiás, 2024-07-26) Silva, Ramon Miranda; Almeida, Tatiana Duque Martins Ertner de; http://lattes.cnpq.br/9082478597898534; Almeida, Tatiana Duque Martins Ertner de; Colmati Júnior, Flávio; Barbosa, Martin Schwellberger; Talhavini, Márcio; Zalloum, Neife Lilian
Luminescent organic compounds play an essential role in the fabrication of photosensitive active layers, spanning a variety of applications from sensors to lightemitting diodes, photovoltaic systems, among others. In this context, we explored the creation of multilayer films from a hybrid Perovskite (P), with the configuration CH3NH3SnIxCl3-X, combined with recognized electroluminescent compounds such as Rubrene (R), and the polymer Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], MEH-PPV (M), which were deposited by the Layer-by-Layer and spin-coating techniques, and their photophysical properties were studied. Using steady-state and time-resolved fluorescence spectroscopy, it was possible to evaluate the optimal conditions for the production of thin films of the isolated compounds and combinations of interest (bi- and trilayers - P/M; P/R; P/M/R and P/R/M), as well as their photophysical properties. Steady-state electronic spectra demonstrated higher efficiency for films prepared from the deposition of layers of perovskite, Rubrene, and MEH-PPV, using solutions with concentrations of 0.6 – 10-5 and 10-8 mol.L-1, respectively. The layer-by-layer technique involved a 90-second immersion, and spincoating films required 100, 40, and 60 seconds of spin-up rotation for perovskite, Rubrene, and MEH-PPV, respectively. Single point and lifetime mapping analyses, using pulsed lasers (373, 452, and 507 nm), indicated tri-exponential behavior in all evaluations. The results showed for P/R layer-by-layer and spin-coating bilayers excited states with greater sensitivity to the excitation wavelength, prolonging lifetimes with decreasing irradiation length. Mapping analysis indicated regions with higher Eficiência de FRET for P/R when excited at 373 and 452 nm, and for P/M at 507 nm excitation. The Single point data of the Trilayers showed that the inversion in the order of deposition of the semiconductors directly influenced the formation of the system's excited states, with the P/M/R film showing greater sensitivity to the photophysical processes as the excitation length varied. and P/R/M greater stability. Mapping indicated higher FRET rates for P/M/R produced by layer-by-layer, which was selected for UV-Vis sensing studies
Deciphering the stereoselectivity of Claisen rearrangements: joint density functional theory and machine learning models
(Universidade Federal de Goiás, 2024-01-29) Oliveira, Ana Gabriela Coelho; Oliveira, Heibbe Cristhian Benedito de; http://lattes.cnpq.br/ 5995553993631378; Oliveira, Heibbe Cristhian Benedito de; Alonso, Christian Gonçalves; Muniz, Aline Silva; Silveira Neto, Brenno Amaro da; Oliveira, Guilherme Colherinhas de
In the present study, the stereoselectivity of Claisen Rearrangements was addressed, focusing on the influence of two distinct electron-withdrawing groups and eight different substituents in three variants of the rearrangement: Hurd, Eschenmoser, and Johnson. Using the Curtin-Hammett principle, the energies of reactions, products, and transition states were calculated using the M062X/def2TZVPP theory level. The results indicate that kinetic effects predominantly govern the reaction equilibrium. A key aspect of our investigation involved applying Shubin’s energy decomposition analysis to the optimized transition states. This approach highlighted the significant influence of the electrostatic component on stereoselectivity, revealing its predominance over the quantum and steric components. Moreover, each transition state was divided into four fragments: the electron-withdrawing groups (Ester and Nitrile), the specific Hurd/Esch/John group (H, NMe2, and OEt), various substituents (alkyl and aryl), and the central fragment. This fragmentation allowed for a comprehensive analysis of the dipole moments of the groups and non-covalent interactions, providing insights into the electrostatic forces driving the rearrangement process. In addition, Supervised Machine Learning algorithms were employed, focusing on the analysis of electronic and geometric datasets related to the transition states. The results obtained not only elucidate the mechanisms underlying the stereoselectivity of Claisen Rearrangements but also provide a subtle understanding of the interaction between different molecular components, establishing new perspectives in advanced applications in organic synthesis.
Estudo de degradação forçada e de compatibilidade do ciprofibrato com excipientes farmacêuticos
(Universidade Federal de Goiás, 2022-08-31) Brito, Camila Cíntia Sousa Melo; Leles, Maria Inês Gonçalves; http://lattes.cnpq.br/1614912440064013; Leles, Maria Inês Gonçalves; Siqueira, Adriano Buzutti de; Chaves, Andrea Rodrigues; Ionashiro, Elias Yuki; Ribeiro, Elton Brito
Ciprofibrate-CPF is a hypolipidemic that promotes the reduction of serum levels of cholesterol and triglycerides by stimulating activated nuclear receptors for peroxisome proliferation-alpha-PPAR-α. In this work, the stability of CPF was studied using forced degradation and compatibility studies. The Active Pharmaceutical Ingredient-API (SQC) was characterized by Thermogravimetric Analysis/Derivative Thermogravimetric AnalysisTGA/DTGA, Differrential Scanning Calorimetry-DSC, Differrential Scanning Calorimetry coupled to the Photovisual system-DSC-Photovisual, Absorption spectroscopy in the mid-infrared region with Fourier Transform-FTIR, Nuclear Magnetic Resonance-RMN, Powder X-ray Diffractometry-DRXP, High Resolution Mass Spectrometry-EMAR and High Performance Liquid Chromatography coupled with Diode Array Detector and High Resolution Mass Spectrometry-CLAE/DAD/EMAR. The forced degradation study was carried out for CPF (SQC) under the following conditions: acid hydrolysis, basic hydrolysis, oxidative and thermal at 70 °C 240 hours using EMAR and CLAE/DAD/EMAR. The compatibility study between the CPF and the excipients was carried out by preparing binary mixtures in the proportions 50:50 and 92:08 (m/m), where the isolated components (CPF (SQT) and excipients), Simulated Excipients Sample-ASE (excipients) and the binary mixtures (CPF-excipient or CPF-excipients) were analyzed by TGA/DTGA, DSC, DSC-Photovisual, FTIR, and DRXP. The EMAR and CLAE/DAD/EMAR results suggested the degradation of CPF when subjected to basic hydrolysis, with some degradation products previously reported in the literature being observed and a new product identified. In the other exposure conditions, the CPF remained stable. The DSC technique suggested signs of interaction between the CPF and the excipients (Sodium Starch Glycolate-AGS, Sodium Lauryl Sulfate-LSS, Silicon Dioxide-DOS and Hydrogenated Vegetable OilOVH) when prepared in a proportion 50:50 (m/m) and between CPF and the excipient (OVH) in a proportion (92:08 m /m). However, the FTIR and DRXP techniques did not confirm the sings of interaction observed in the DSC, except when DOS was used at 50%. The compatibility study indicated the use of the CPF-ASE binary mixture in the proportion 50:50 (m/m) as a candidate for pre-formulation.
Determinação de ácidos orgânicos em amostras alimentícias e petroleômicas utilizando sistemas eletroforéticos
(Universidade Federal de Goiás, 2022-06-30) Pinheiro, Kemilly Mara Pires; Coltro, Wendell Karlos Tomazelli; http://lattes.cnpq.br/8302650734477213; Coltro, Wendell Karlos Tomazelli; Vaz, Boniek Gontijo; Lago, Claudimir Lúcio do; Richter, Eduardo Mathias; Micke, Gustavo Amadeu
This study describes the use of microchip electrophoresis coupled to contactless conductivity detection for the determination of inorganic and organic anions for food and petroleomics application. Also, describes the use of capillary electrophoresis coupled to mass spectrometry for petroleomic application. Organic acids are responsible for several wines characteristics, such as aroma, flavor, color and stability. Their analysis are important for monitoring fermentation process and the quality of wines. 12 anions were detected and separated within 100 s, using a buffer composed of 30 mmol L-1 OF 2-(N-Morpholino)ethanesulfonic acid, 15 mmol L-1 of histidine and 0.05 mmol L-1 of cetyltrimethylammonium bromide (pH 5.8). 18 wine samples were analyzed and it was possible to detect and quantify sulfate, phosphate, tartrate, maleate, succinate, acetate and lactate. A multivariate approach was used to investigate the similarities among anionic profile of the wines, and it was possible to discriminate samples mainly by grape varieties, production region and winemaking process. Naphthenic acids are carboxylic acids naturally occurring in crude oil with one or more ring structures. They are present in produced water, which is the water obtained with petroleum during its prospection and are responsible for corrosion, naphthenates deposition, and harmful to the environment when disposed of without treatment. The acids benzoic, 1-naphthoic and 9-anthracenecarboxylic were separated and detected using a microsystem electrophoresis coupled to contactless conductivity detection. The analysis was performed within 140 s using a buffer composed of an equimolar mixture of 10 mmol L-1 of sodium carbonate and bicarbonate (pH 10.2). 5 samples of produced water were analyzed and it was possible to detect and quantify 9-anthracenecarboxylic acid, demonstrating to be an efficient tool for analysis of complex samples matrices for petroleum applications. In this way, electrophoresis microchip proves to be a simple and portable analytical platform for field analysis, proving to be promising for wine quality control and for monitoring the presence of naphthenic acids in produced water samples. A capillary electrophoresis system coupled to a mass spectrometer was also used to analyze naphthenic acids. It was possible to detect cyclopentanecarboxylic acid, benzoic acid, cyclohexanebutyric acid, 1-naphthoic acid, decanoic acid, 3,5-dimethyladamantane-1-carboxylic acid, 9-anthracenecarboxylic acid, pentadecanoic acid and 2-methyl-octadecanoic acid within 13 min using a buffer composed of 40 mmol L-1 of ammonium hydroxide, 32 mmol L-1 of acetic acid and 20% isopropanol (pH 8.6). Produced water samples were analyzed and it was possible to identify and quantify cyclopentanecarboxylic, benzoic, cyclohexanebutyric and decanoic acids. In this way, the proposed method demonstrated to be efficient to detect naphthenic acids analysis in complex samples of produced water using capillary electrophoresis coupled with mass spectrometry. The next steps of this study are the evaluation of other acids in produced water samples for quantification of total acids.
Desenvolvimento de metodologias miniaturizadas de preparo de amostras para a avaliação de pesticidas multiclasses em amostras ambientais
(Universidade Federal de Goiás, 2023-09-05) Martins, Rafael Oliveira; Silva, Bruno José Gonçalves da; http://lattes.cnpq.br/6550581465780888; Chaves, Andréa Rodrigues; http://lattes.cnpq.br/6064014965252121; Chaves, Andréa Rodrigues; Nascentes, Clésia Cristina; Coltro, Wendell Karlos Tomazelli; Hantao, Leandro Wang; Sgobbi, Lívia Flório
The presence of pesticides in the environment is primarily due to the excessive use of these chemical compounds in the global agricultural scenario. In recent decades, the search for new approaches to the analysis and monitoring of these compounds in such matrices has focused on the introduction of sample preparation methodologies as analytical strategies responsible for assessing such complex matrices. Furthermore, the evolution of these sample preparation methodologies over the decades has brought with it the introduction of miniaturized systems capable of overcoming classical challenges faced by conventional sample preparation method-ologies. Thus, this study presents the evaluation of three miniaturized approaches for pesticide extraction in environmental samples. Chapter II presents the development and application of the Hollow Fiber Liquid-Phase Microextraction (HF-LPME) technique for the assessment of 13 multi-class pesticides in soil samples. The methodology reported in the first chapter resulted in R² values >0.98 for all pesticides and detection and quantification limits (LOD and LOQ, re-spectively) in the range of ng L-1 and recovery values between 75.2%-118.8%. The evaluation of the methodology proposed by the AGREEprep software indicated that approximately 70% of the method adhered to the principles of green chemistry adopted by the software. Furthermore, a comparison with classical methods of pesticide extraction in soil identified the HF-LPME method as an efficient approach for monitoring pesticides in soil. Chapter III describes the application of the Electromembrane Extraction (EME) technique for the evaluation of the same set of analytes in soil samples. In this second approach, a special focus was placed on com-paring the proposed method with the one applied in Chapter II, regarding analytical frequency, green aspects, and analytical performance of both methods. Differences were observed in an-alytical aspects, where the EME technique showed higher LOD (76.1 -171.4 μg kg-1) and LOQ (270.7 -516.1 μg kg-1) values than the HF-LPME technique (66.1 -198.1 μg kg-1) and (92.7 -331.2 μg kg-1), respectively. Despite this, values closer to 100% were obtained with the EME technique. A higher analytical frequency was achieved with the EME technique (4 extractions/h) compared to HF-LPME (2 extractions/h). Regarding green chemistry aspects, due to the use of external energy, the methodology proposed by EME showed significant energy consumption. Finally, Chapter IV presented a detailed study of the influence of parameters involved in the on-chip electromembrane extraction technique of the pesticides Carbofuran and Carbendazim in river water samples. This chapter focused on two main aspects: (I)the optimization of the device to reduce leakage during extraction, as it is a disadvantage of the conventional system, and (II)evaluating the differences in the extraction of ionizable and neutral compounds by the on-chip electromembrane extraction system. The optimization of the device introduced the OSTE sealing material as an approach to prevent leaks, allowing for the use of flow rates of 300 μl/min-1 without observing leaks. The evaluation of the parameters involved in the technique showed the dependence of the physicochemical characteristics of the pesticides on the pro-posed system, revealing the extraction of the pesticides in their charged and neutral forms. The analytical evaluation of the method showed LOD and LOQ values ranging from 158.4 to 256.2 μg L-1and 528.1 to 854.1 μg L-1, respectively, and recovery values ranging from 26.3% to 53.8%, indicating an influence of the matrix that was confirmed by the matrix effect study. The study of the pesticides Carbaryl and Carbendazim proved to be an important approach to further expand the field of applications of the on-chip electromembrane extraction technique. The methods described here have proven to be effective analytical strategies for assessing pesticides in en-vironmental samples. The development of the methodologies presented here further expands the possibilities for monitoring pesticides in such complex samples as environmental ones. The application of the proposed methodologies offers a possible strategy for evaluating the effects of these compounds on the environment and proposing ways to identify contaminants in differ-ent environmental compartments.
Síntese e caracterização de catalisadores nanoestruturados contendo PtSnCu para a oxidação eletroquímica de etanol
(Universidade Federal de Goiás, 2019-11-28) Magalhães, Monah Marques; Colmati Júnior, Flávio; http://lattes.cnpq.br/0231242349462585; Colmati Júnior, Flávio; Ribeiro, Josimar; Souza, Elki Cristina de; Sgobbi, Lívia Flório; Cabral, Murilo Feitosa
Renewable energies are increasingly desirable. One of the proposed alternatives is proton-exchange membrane fuel cells (PEMFC). The use of ethanol as fuel in these cells is advantageous because it has a low contribution to the greenhouse effect when the CO2 cycle is completed. However, complete oxidation of the ethanol requires the breaking of the CC bond, to oxidize the intermediates that are formed during the reaction, which are stable and if not oxidized promote a decrease in the efficiency, due to the poisoning of Pt. The study is presented with catalysts of PtxSnyCuz supported on high surface area colloidal carbon. The electrocatalysts were produced with the alcohol reduction method. The synthesis used with modification to obtain the materials allowed the formation of nanoparticles with high catalytic activity, in the range of 2 to 3 nm. The physical characterization techniques used, such as XRD, MET and XPS, allowed to verify that the particles are crystalline, with majority crystal of the CFC structure of Pt, and that Sn and Cu atoms were inserted in this crystal, causing modifications in the peaks to the crystalline planes of the Pt network. Microscopies showed the morphology of the nanoparticles and helped to understand the relation of the high catalytic activity with the good dispersion of particles and their high surface area coming from their size. The analysis by XPS allowed to prove the elements present in the samples, besides determining the composition of atoms in the surface in which the catalysis occurs. The electrochemical characterization by VC showed the high activity of the ternaries with low potential values for the beginning of the ethanol oxidation compared to the Pt/C, PtSn/C and PtCu/C catalysts. The chromaamperometric technique evaluated the stability of the catalysts and verified that in the studied time the materials have constant and stable behavior. Through the EIS it was possible to understand the electrical resistance of the catalytic surface and to verify that such property for the ROE decreases as the potential increases, the studied compositions showed that the composition of the material influences in the reduction of the electrical resistance when oxidizing the molecule of ethanol and that can two or more reaction mechanisms occur during catalysis.
Estudo químico, quimiotaxonômico e avaliação antiofídica de espécies dos gêneros Copaifera e Marsypianthes
(Universidade Federal de Goiás, 2022-12-21) Teixeira Júnior, Eurides Francisco; Kato, Lucilia; http://lattes.cnpq.br/1362891438631386; Kato, Lucilia; Torres, Ana Maria; Silva, Carmelita Gomes da; Rosa, Jeane; Sena, Marcelo Martins de
Snakebites have a major impact on public health, especially in isolated communities without access to prompt medical attention. There are about 100,000 deaths per year caused by snakebites and three times as many sequelae. The antivenom is the conventional treatment, but it has no action at the site of the bite in the human body and is not always within the reach of victims in isolated locations. The use of plants as treatment in case of snakebites is a reality, because it is an accessible way, with lowcost resource that attenuates the local effects of the bite too. The species Marsypianthes chamaedrys, known in the northern region as Boia-cáa or Paracari, is widely used in these cases. In Brazil, besides M. chamaedrys, also occur M. foliolosa, M. montana, M. burchelli, M. hassleri and M. tubulosa. Except for the first, the other species are still poorly studied. This work allowed the annotation of metabolites and evaluation of the anticoagulant and anti-hemolytic action for Marsypianthes species not studied so far. The anti-hemolytic action of the M. montana extract stands out. In ethnobotanical studies, the oil extracted from the trunk of copaibas is reported in cases of ophidic accidents. In this study, we confirmed the anticoagulant and anti-hemolytic action of the leaf extract of different taxa of Copaifera against Bothrops alternatus venom. The species Copaifera sp. and C. marginata totally inhibited the coagulant action of the venom, and the latter showed more than 95% inhibition of hemolytic activity. The Copaifera genus is composed of over 70 species, of which 16 occur only in Brazil. There are many gaps in the correct identification of species and varieties of this genus. Using direct infusion mass spectrometry data associated with chemometric methods such as PLS-DA, it was possible to identify the main ions responsible for the distinction of four taxa of Copaifera, including varieties of the same species. Thus, this work fulfills its objective of providing chemical and biological information about species of the genera Copaifera and Marsypianthes. Taking advantage of powerful tools such as the HPLC-MS/MS and the GNPS platform, it was possible to note several metabolites, among which, many phenolic compounds, which may be associated with the investigated antiphidic actions.
Gaseificação catalítica de efluente da indústria de biodiesel para a produção de hidrogênio
(Universidade Federal de Goiás, 2023-04-28) Mourão, Lucas Clementino; Alonso, Christian Gonçalves; http://lattes.cnpq.br/7285754665946583; Alonso, Christian Gonçalves; Corazza, Marcos Lúcio; Chagas, Rafael Pavão das; Colmati Júnior, Flávio; Alves, Helton José
The increasing global pollution, combined with a growing demand for energy, is driving the search for environmentally-friendly alternatives in energy production. Hydrogen, which has emerged as an important energy vector, is primarily produced from non-renewable sources such as petroleum. The development of innovative technologies has facilitated the utilization of renewable sources for hydrogen production, such as Supercritical Water Gasification (ScWG) of biomass. Among the potential feedstocks for hydrogen production, glycerol, a byproduct of the biodiesel industry, stands out as a promising candidate for ScWG. Due to the increasing production of biodiesel, a large supply of glycerol is being produced without a corresponding increase in demand. As a result, the biodiesel production chain has garnered increased interest from several research initiatives aimed at valorizing waste materials into higher value-added products. Combined with heterogeneous catalysis, the ScWG process can increase selectivity towards products of interest and achieve high conversion efficiency of organic matter, even with short residence times. In this work, the catalytic gasification of glycerol and real wastewater from a biodiesel industry were evaluated. Ni based catalyst were synthetized by simple and fast wet impregnation method of metallic nitrates supported on a honeycomb cordierite (CRD) structure. The catalysts were characterized by SEM-EDS, XRD, N2 adsorption/desorption, XRF, WDS and TGA. The performance of the Ni-based catalyst was evaluated in the ScWG of glycerol and compared to two commercial Automotive Catalysts (ACs). The ScWG of glycerol was carried out under different conditions in order to establish optimal operating parameters. The tests were conducted at reactor temperatures ranging from 400ºC to 700ºC, a system pressure of 25 MPa, and glycerol mass concentrations ranging from 10% to 34%. For optimal conditions (600 ºC and glycerol 10wt%), the results indicated that Ni/CRD catalyst showed the highest H2 yield (1,40 mol/mol C) and carbon conversion (95%). Although they have shown efficiency in the gasification of glycerol, the ACs showed higher tendencies for activity loss in carbon conversion compared to Ni based catalys over time (300 min). Preliminary tests using real industrial effluent (BIOD) were conducted, evaluating parameters of temperature (400 - 600°C), feed flow rate (10 - 20 mL/min), and effluent concentration based on total organic carbon (TOC) (50 - 100%). The results showed that temperature had the greatest influence on gasification, with a carbon conversion of 77% and an H2 yield of 2.85 mol/mol C at 600°C (10 mL/min; 50% TOC). Catalytic test conducted under the best condition (600 ºC; 10 mL/min; 100% TOC) showed higher carbon conversion, while non-catalytic test obtained higher H2 selectivity (76%). The results showed that structured catalyst has great potential to enhance the production of H2-rich gas specially from glycerol GASc. The use of biodiesel residue as a raw material for the ScWG process is promising since it allows the treatment of the residue and the production of H2-rich gas simultaneously.
Desenvolvimento de novos sais do fármaco adifenina com estabilidade física e química aprimoradas, avaliação da biodisponibilidade e estudos de estabilidade físico-química em formulação
(Universidade Federal de Goiás, 2022-06-23) Ribeiro, Thiago de Freitas; Oliveira, Cecília Maria Alves de; http://lattes.cnpq.br/3152041311943092; Oliveira, Cecília Maria Alves de; Doriguetto, Antônio Carlos; Carvalho, Jesiel Freitas; Gomes, Danielle Cangussu de Castro; Kato, Lucília
Here we have solved the adiphenine solid-state hygroscopicity problem through the preparation of stable, non-hygroscopic multi component crystal forms thereof. Two new salts of adiphenine were designed by recognition of intermolecular interactions patterns in the Cambridge Structural Database (CSD) and pKa rules. Some conformants, Generically Recognized as Safe (GRAS), namely malic acid, fumaric acid, lactic acid, citric acid and oxalic acid, were selected for the synthesis of monobasic salts with an adiphenine base, and they had a favorable result in this two synthesis step, namely, are the citrate and oxalate salts. Crystal structure elucidation reveals that adiphenine adopts different conformations in our salts and in the literature hydrochloride one, which is related to different intermolecular arrays. The adiphenine hydrochloride exhibits a classical high hygroscopicity behavior, which retains water fast from 50% of relative humidity (RH), increasing up to 22% of its initial mass in 90% of RH and a net mass gain of 5% at the end of the desorption cycle (RH = 0%). In the dynamic vapor sorption(DVS) analysis, it was verified that adiphenine citrate and adiphenine oxalate starts to incorporate water slowly from 50% and 70% of relative humidity (RH), increasing up to 3.2% and 2.6% of their initial masses in 90% of RH, respectively. At the end of the desorption cycle (RH = 0%), the samples retained only 0.12% and 0.08% of water relative to their initial masses. Notably, both carboxylic acid salts had similar solubility as a function of medium pH, while the hydrochloride one was more soluble than them by factors ranging from 6.7 (relative to citrate in pH 1.2) to 28.2 (relative to oxalate in pH 4.5). Nevertheless, them pharmacokinetic parameters of adiphenine after oral administration of the capsules containing the salt forms did not reflect these solubility differences, since all adiphenine salt forms can be considered highly soluble drugs according to Biopharmaceutics Classification System (dose/solubility ratio <250mL). It was observed that the rats treated with capsules containing adiphenine hydrochoridrate had an increase in AUC0-∞ (1537 vs 914 vs 991 min μg mL-1 ) compared with rats treated with adiphenine citrate and oxalate capsules, respectively, even though the same Tmáx (48 min) was observed. The dosage tuning can bring the bioavailability of our salts into that of the hydrochloride salt, with the advantage of non-hygroscopicity and higher chemical stability. The study stability was also carried out in a known formulation and the result obtained confirmed that the new adiphenine salts are more stable when exposed to stress conditions. The evaluation of the stability of the adiphenine salts in the formulation was carried out in such a way that it was possible to assess whether the adiphenine salts would withstand certain stress conditions in the salt form and after being incorporated into the formulation. Under photolytic and humid thermal stress conditions, the stability of the new adiphenine salts is remarkable, since the content obtained did not show a sharp drop, in addition, the main adiphenine degrading agent did not show a high % when compared to commercially available salt. We highlight, in isolated active pharmaceutical ingredients, the degradation between the commercially available salt and the new salts is similar with degradation lower than 1.6% when exposed to wet thermal and photolytic conditions. However, when active ingredients are incorporated into a formulation, the difference in the degradation process is clear. Since the commercially available salt degraded 9.5% in the thermal condition and 2.5% in the photolytic condition in variation the new salts of adiphenine citrate and oxalate degraded 1% and 1.9% in the thermal condition and 0.7% and 1.0% in the photolytic condition, respectively
Estudo do cloridrato de fenilefrina em associação com outros insumos farmacêuticos ativos: compatibilidades físico-químicas, identificação e qualificação de produtos de degradação
(Universidade Federal de Goiás, 2022-09-02) Silva, Alisson Moraes e; Oliveira, Cecília Maria Alves de; http://lattes.cnpq.br/3152041311943092; Oliveira, Cecília Maria Alves de; Martins, Felipe Terra; Leles, Maria Inês Gonçalves; Valadares, Marize Campos; Guimarães, Vinícius Ferraz
Phenylephrine hydrochloride is a medication widely used in medicine to increase blood pressure during surgical procedures and to promote objective and subjective relief of nasal congestion in patients with the common cold. For this reason, it is largely used in fixed-dose combination medicines, associated with active pharmaceuticals ingredients (APIs) such as acetaminophen, caffeine, dexchlorpheniramine maleate, pheniramine maleate, and acetylsalicylic acid. Given the well-known chemical instability of phenylephrine hydrochloride and in order to increase the knowledge about the interactions of this API with other medications, in this thesis the results of Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) curves of isolated APIs: phenylephrine hydrochloride, paracetamol, caffeine, acetylsalicylic acid, dexchlorpheniramine and pheniramine maleates and the drug-drug compatibility studies under stress conditions, in solid phase, for binary mixtures containing phenylephrine hydrochloride in association with other APIs were evaluated and discussed. Furthermore, in order to obtain data on the degradation products formed from the interactions of the associations tested, the use of techniques such as high-performance liquid chromatography coupled with ultraviolet-visible detector (HPLC/UV-VIS) and with high resolution mass spectrometer (HPLC/HRMS) were employed to quantify and elucidate the structures of impurities formed in the associations tested and in products available in the local market. The genotoxic potential of these compounds was also evaluated in silico using the Genotox-iS® 3.0 toxicological prediction software. The data obtained attested that phenylephrine hydrochloride is a hygroscopic API, physically incompatible with acetylsalicylic acid and with APIs that have maleate as a counterion. The investigation of the degraded samples allowed elucidating the structures of the degradation products formed of which only compounds named in this work as I and IV are reported in the literature, however, without mention for their toxicity. The detected degradation products were qualified in silico according to the prerogatives of the The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) M7 guide, and categorized as class 5 (non-mutagenic): compounds I, II and III and class 3 (structural alert, not related to the structure of the drug substance; no mutagenicity data): compound IV. Three of the commercially available medicines tested exhibited the presence of high concentrations of Compound I.

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