Resumo em Português:

A method for determining Cd, Cr, Cu, and Fe in biodiesel samples is proposed using energy dispersive X-ray fluorescence spectrometry (EDXRF) after extraction induced by emulsion breaking (EIEB). A volume of 7.0 mL of biodiesel and an aliquot of 500 µL of Triton X-100 solution (2%, v v-1) prepared in nitric acid were used to prepare the emulsion. After 5 min of manual agitation, phase separation was performed by centrifugation for 5 min at 2000 rpm. A 100 µL aliquot of the enriched aqueous phase was collected and applied to the center of a filter paper. After drying, the analysis was performed directly on the paper using EDXRF. The detection limits were 60, 20, 30, and 60 μg kg-1 for Cd, Cr, Cu, and Fe, respectively. Recovery tests were performed by adding 450 μg kg-1 of the analytes in biodiesel samples, and the results varied between 87 and 113%. The procedure was applied to biodiesel samples, and the concentrations obtained for the four analytes were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP OES) after sample digestion.

Resumo em Inglês:

The objective of this work was the detection and traceability of the occurrence of diethyl phthalate (DEP) migrating from flexible packaging to food. Brazil is one of the largest producers of flexible plastics widely used in food. The evaluation of migrations of contaminants for food, mainly fatty foods, elucidates the possible transmission of diseases through the daily consumption of migrant contaminants from packaging. Throughout an accurate and highly specific methodology, with no use of simulants or organic solvents during sample preparation, the proposal of this study obtained a direct DEP ranking through migration traceability via headspace: HS-GC-MS. Of the 9 samples of flexible packaging and packaged foods analyzed, DEP was identified in 100%, thus confirming its occurrence in foods. Despite the storage conditions: temperature, shelf life, fat content of the products and the manufacturer’s assessment of use. It is urgent to review official standards to promote intense restrictions on the occurrence of DEP in food and encourage the benefits of reflecting daily consumption habits.

Resumo em Inglês:

BiOCl nanosheets modified with AuCu nanoparticles were successfully designed and fabricated for water reduction of CO2. The AuxCuy/BiOCl composites exhibited enhanced visible light absorption ability due to a surface plasmon resonance (SPR) effect. The AuxCuy/BiOCl composites could convert carbon dioxide to ethane (C2H6), while only CO was obtained over pure BiOCl nanosheets. In this study, the rate of C2H6 production (12.2 μmol h-1 g-1) and selectivity of C2H6 (75.7%) were obtained over the Au1Cu1/BiOCl photocatalyst under simulated sunlight illumination. The AuCu nanoparticles played the dual role of electron traps and hot electron donors, facilitating efficient separation and migration of the carriers. The photocatalyst exhibited steady photocatalytic activity over the test duration of 9 h.

Resumo em Inglês:

In this work we described the synthesis and characterization of a series of novel chiral 1,5-diamines derived from (R)-(+)-camphor through simple procedures in moderate to good yields. These new enantiopure compounds constitute a new family of chiral diamines with potential applicability as chiral building blocks, bioactive products or chiral ligands for asymmetric transformations.

Resumo em Português:

There is a demand for new technologies to replace fossil resources in activities due to environment concerns. In the circular economy, materials to be discarded are reused and reenter to the economy. An alternative for the plastic problem would be preparation of fiber-reinforced plastics from renewable sources. Herein polymeric films were prepared with starch, glycerol and bagasse derivatives. Some characterization techniques were presented to indicate the best applications. It was identified that higher glycerol ratio films are more malleable and have a higher humidity and solubility. The DSC scans for each film shows no increase in glass transition temperature. Biodiesel films are an alternative for the circular economy of waste and the biodiesel industry, since the study proved to be an alternative for the plastics currently used. This work will certainly attract the students’ interest, because the theme is in their daily lives, also bringing the precepts of sustainability and green chemistry.

Resumo em Inglês:

This work explores the possibility of using corn cob powder as a carrier for immobilization by physical adsorption of lipase from Rhizopus oryzae used in acidolysis reaction of grape seed oil with capric acid (C10) to synthesize dietary triglycerides (TAGs) formed from medium-long-medium chain (MLM) fatty acids in a fixed bed reactor. First, enzymatic loading was investigated to improve hydrolytic activity and the immobilized biocatalyst was characterized in terms of biochemical parameters and thermal stability. An enzyme load of 30 mg mL-1 was quite adequate, as about 90% of the immobilization yield was achieved. The central composite rotatable design (CCRD) experimental design revealed that, for the immobilized enzyme, the optimal hydrolytic activity was obtained at pH 7.75 and 41 °C. Stirred tank reactions were optimized in CCRD statistical analysis revealing the most desirable conditions for molar ratio of 1:9.36 (oil:acid), 45 °C and 15% biocatalyst, obtaining a maximum ID value of 86.93 ± 2.25%. In a fixed bed reactor, the synthesis showed an average ID of 51.13 ± 0.77, demonstrating the potential of this configuration. It is concluded that corn cob powder as an immobilization carrier is a promising alternative for the enzymatic synthesis of MLM triacylglycerols.

Resumo em Português:

This study aimed to synthesize novel compounds as more effective carbonic anhydrase II inhibitors. For this purpose, 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4,5-diphenyl-1H-imidazole (3) was reacted with 3-methoxy-4-(prop-2-yn-1-yloxy)benzaldehyde through the glyoxal reaction to produce a series of imidazole-based 1,2,3-triazoles 5a-f. The synthesized compounds were structurally confirmed using IR, 1H, and 13C NMR techniques. To evaluate their potential as inhibitors of carbonic anhydrase II enzyme, the synthesized compounds were tested via in vitro enzyme inhibition assay. Among the derivatives, compounds 5f and 5a exhibited the most promising inhibitory potential, with IC50 values of 0.025 ± 0.001 and 0.032 ± 0.003 µM, respectively. Both 5a and 5f derivatives have comparable inhibitory potential but 5f was found to be more potent than 5a: Molecular docking analysis revealed that compounds 5a and 5f displayed excellent binding scores of -8.0 and -8.4 kcal mol-1, respectively. The results were further validated by MD simulations. The RMSD analysis revealed the average values of 3.20 Å for the ligand-protein complex, 1.38 Å for the apoprotein, and 7.15 Å for the ligand molecule. Based on the chemical stability and biological importance, the compound 5f was identified as potential lead candidates for the development of more effective carbonic anhydrase II inhibitors.

Resumo em Português:

This study aimed to determine the total contents of copper, iron, and zinc in camapu and protein fractions by inductively coupled plasma emission spectrometry. Firstly, lipid removal was performed using chloroform and methanol (2:1). Protein fractions were obtained after sequential extraction using four extractors (water, 0.5 mol L-1 sodium chloride, 50% acetic acid v v-1 and 0.05 mol L-1 sodium hydroxide). The camapu sample and protein fractions were digested in a cavity-microwave oven with diluted nitric acid and hydrogen peroxide. The accuracy of the procedure was evaluated using the addition and recovery method in the digests and protein extracts. All the elements were determined in the protein fractions. Levels of Cu, Fe, and Zn ranged from 0.07 to 0.5 mg kg-1 were found in the lipid fraction. The residue presented higher iron content compared to other elements. Higher Cu and Zn contents were found associated with albumin. All elements studied were found in the protein fractions, and the total protein concentration determined in each protein fraction was 5.74 mg kg-1 (albumins), 0.28 mg kg-1 (globulins), 4.46 mg kg-1 (glutelins 1) and 0.46 mg kg-1 (glutelins 2).

Resumo em Português:

Bordeaux S is a food dye still allowed in Brazil, being present in soft drinks, gelatins, chewing gums, candies and many other industrialized foodstuffs. Because of its carcinogenic potential, it is forbidden to be added to food in Japan, in the USA and in most of the European Union. Many studies related to the employment of digital images analysis to food quality control have been published in recent years mainly due to its low costs of implementation. Nevertheless, one of the few drawbacks of applying this technique is its poor sensitivity, which can be significantly improved by employing solid substrates, such as chitosan films. In this work, chitosan sorbent films were synthesized, characterized and used to retain Bordeaux S present in gelatin samples, followed by recording the films’ images and quantifying the analyte by digital images analysis. The proposed method was able to extract the analyte and eliminate interferences present in the matrixes in a single step. LOD of 20 µg L-1 and LOQ of 74 µg L-1 were obtained, allowing adequate quantification when considering the recommendations of the Brazilian Health Regulatory Agency (ANVISA).

Resumo em Português:

The reduction of nitroarenes is the main methodology to produce anilines, important precursors of building blocks, dyes, and drugs. Continuing our goal of describing sustainable methodologies for the reduction of nitroarenes to their respective anilines, herein we compile selected reaction protocols, using organic medium, reported from 2017 to 2023, in order to provide a comprehensive and complementary view of the new processes and catalysts developed during this period.

Resumo em Português:

During the COVID-19 pandemic, the pursuit of a cure for the disease resulted in an excessive consumption of various pharmaceuticals, even after their inefficacy had been scientifically demonstrated. This scenario highlights the urgency of educational initiatives that improve students’ critical thinking and promote awareness of indiscriminate use of pharmaceuticals and its environmental and social implications. This research described the educational initiative “Pharmaceuticals in the COVID-19 pandemic” based on the study case method, implemented at an analytical chemistry class, and analyzed its potential on promoting Critical Environmental Education through a content analysis guided by the indicators proposed by Luz and Tonso. Students were divided into groups and studied different cases about pharmaceuticals featured in the media during the pandemic. They were expected to gather relevant data regarding the case scenario; to take a position on a socio-environmental dilemma; propose an analytical chromatographic methodology for the pharmaceutical in the case and present their results in a final report. The educational initiative was considered aligned with Critical Environmental Education principals due to the presence of six out of the seven indicators. As a future perspective, we aim to optimize the educational initiative in order to include all the indicators and students’ suggestions.

Resumo em Português:

Over the years the study of the quantitative structure-activity relationship (QSAR) has transformed from a simple regression analysis to the implementation of machine learning (ML) with multiple statistics. Today ML-based QSAR models are quite important and play a notable role in drug design and screening, property prediction, biological activity, etc. ML methods applied to QSAR build classification or regression models to describe/predict the complex relationships between the chemical structure of molecules and biological activity. Even with the increase in scientific publications addressing this topic written in Portuguese, there is still a shortage of scientific articles explaining ML techniques applied to QSAR, how to build models, the types of models, algorithms, for the Brazilian scientific community. And to fill this need, we intend to approach the subject in a simple and didactic way for students and researchers who are starting in this very promising and important area. We will describe the fully explained theory of machine learning by applying QSAR, abstracting the complexity, and well-illustrated.