Química Nova, Volume: 44, Issue: 8, Published: 2021
  • HIGHLY SELECTIVE HF-LPME-GC-MS FOR COCAINE AND BIOTRANSFORMATION PRODUCTS IN HUMAN HAIR TO MONITOR DRUG ADDICTS Artigo

    Scanferla, Deborah Thais Palma; Sakurada, Jessica Yuri; Oliveira, Luís Otávio de; Lini, Renata Sano; Aguera, Raul Gomes; Madia, Mariana Aparecida Oliveira; Moreira, Paula Pessoa; Romoli, Jessica Cristina Zoratto; Bando, Érika; Machinski Junior, Miguel; Marchioni, Camila; Mossini, Simone Aparecida Galerani

    Abstract in English:

    This study aimed to investigate a miniaturized extraction methodology with analysis by GC-MS for simultaneous detection and quantification of cocaine (COC), benzoylecgonine (BZE) and cocaethylene (CE) in hair to monitor drug addicts. The process was done following the international guide of the Scientific Task Force on Forensic Toxicology. After sample extraction, derivatizing solution was added, clean-up was done by the Hollow Fiber Liquid Phase Microextraction (HF-LPME) and adapted to use the ultrasonic bath, a simple and easy-to-handle device. Isobutylchloroformate was first used as derivatization reagent to convert benzoylecgonine to isobutylbenzoylecgonine. Analytes quantification occurred within a linear range of 0.1 to 20 ng mg-1 for COC and 0.05 to 5 ng mg-1 for BZE and CE, with a correlation coefficient of r > 0.99. Limits of detection were 0.05; 0.03 and 0.03 ng mg-1, whereas limits of quantification were 0.1; 0.05 and 0.05 ng mg-1 for COC; BZE and CE, respectively. There was no matrix effect interference. Intra and inter-day precision and accuracy were acceptable according to international guidelines. The analytical method HF-LPME-GC-MS was successfully applied to 14 hair samples from patients admitted in drugs detoxification programs. All samples resulted positive for cocaine (0.80-> 20 ng mg-1) and benzoylecgonine (0.20-> 5 ng mg-1), 11 samples were positive for cocaethylene (0.10-> 0.60 ng mg-1).
  • DFT CALCULATION AND RAMAN SPECTROSCOPY STUDIES OF α-LINOLENIC ACID Artigo

    Peng, Heng; Hou, Hua-Yi; Chen, Xiang-Bai

    Abstract in English:

    Density functional theory (DFT) calculation and Raman scattering experiment have been applied to investigate an important essential fatty acid, α-linolenic acid (ALA). The DFT calculation was performed with geometry optimization and harmonic vibration using B3LYP functions with polarized 6-311+G(d,p) basis. The DFT calculated vibrational modes of ALA molecule are in excellent agreement with the Raman experimental results. A complete vibrational modes assignment is provided on the basis of potential energy distribution calculation. In addition, the DFT calculation and Raman experiment indicate that the relative intensity ratio of two characteristic modes at 1660 cm-1 and 1440 cm-1 is correlated with the number of C=C double bond in the acid chain, which may provide a simple and convenient method to differentiate ALA with other types of unsaturated fatty acids. Furthermore, the Mulliken atomic charge distribution and frontier molecular orbitals of ALA molecule were calculated.
  • AVALIAçãO DE AGROTóXICOS EM SOLO DE SISTEMAS DE PRODUçãO AGRíCOLA CONVENCIONAL E AGROECOLóGICO Artigo

    Morro, Fernanda G.; Schnitzler, Danielle C.

    Abstract in Portuguese:

    EVALUATION OF AGROCHEMICALS IN SOIL OF CONVENTIONAL AND AGROECOLOGICAL AGRICULTURAL PRODUCTION SYSTEMS. At the Contestado Settlement, Lapa, PR, soil samples from agroecological and conventional environments were evaluated against the agrochemicals alachlor, atrazine, chlorpyrifos and trifluralin. For sampling, 3 depths were considered, 10points were selected, 5 in an agroecological and 5 in the conventional environment, with sampling frequency was at 2-month intervals. The samples were characterized according to textural, chemical and fertility parameters and the data were used in the chemometric study (PCA) demonstrating that the environments are different. The method of extraction, identification and quantification was validated at the trace level. The analytes were analyzed by GC-MS/MS, the recovery values were between 83 to 113%, RSD less than 14%, LD equal to 0.01; 0.0028; 0.004 and 002 μg kg-1, LQ equal to 0.04; 0.008; 0.011 and 0.05 μg kg-1, for alachlor, atrazine, chlorpyrifos and trifluralin, respectively. Chlorpyrifos was identified in the Conv3 and trifluralin in the Agro2 and 3 and Conv2 environments. Therefore, the application of pesticides in conventional environments can contaminate agroecological environments. The effect of rain/precipitation on the samples was evaluated by simulation and it was found that the physical-chemical properties of the compounds and the soil have an influence on their behavior in the soil profile.
  • TEORES DE VANáDIO, MOLIBDêNIO E ANTIMôNIO EM SOLOS DE DIFERENTES LITOLOGIAS EM SANTA CATARINA Artigo

    Suppi, Ilana Marin; Campos, Mari Lucia; Miquelluti, David Jose; Machado, Matheus Rodrigo

    Abstract in Portuguese:

    VANADIUM, MOLYBDENUM AND ANTIMONY CONTENTS IN SOILS OF DIFFERENT LITHOLOGIES IN SANTA CATARINA. Trace element levels knowledge in soils is important for establishing quality standards. This study has objective to determine levels of vanadium (V), molybdenum (Mo) and antimony (Sb) in soils from Santa Catarina, observing the different source materials and establishing relationships between these elements and soil properties. The extractions occurred according to USEPA 3051 A protocol, with nitric and hydrochloric acid addition for V and Mo and only with hydrochloric acid for Sb. The quantification of V and Mo occurred by inductively coupled plasma optical emission spectrometry and of Sb by hydride generation inductively coupled plasma optical emission spectrometry. The results were submitted to variance analysis and Scott-Knott test and evaluated by Pearson’s correlation with soil attributes. V and Mo contents differed between soils of different source materials. Highest V levels were found in andesite and basalt soils and Mo in porphyry phonolite, granite, mica schist and sedimentary rocks. V and Sb showed a positive correlation with each other and with oxides of iron, silt, and organic carbon. Mo showed a negative correlation with cation exchange capacity (CEC), iron oxides and organic carbon.
  • COMPOSIçãO QUíMICA E ATIVIDADES FOTOPROTETORA E ANTIRADICALAR IN VITRO DOS GALHOS DE Platonia insignis (CLUSIACEAE) Artigo

    Silva, Andréia G. A.; Moreira, Rodrigo de A.; Sousa, Renato Pinto de; S. M. Filho, Evaldo dos; Veras, Marcia D. A.; Chaves, Mariana Helena; Freitas, Sâmya D. L.

    Abstract in Portuguese:

    CHEMICAL COMPOSITION AND PHOTOPROTECTIVE AND ANTIRADICAL ACTIVITIES OF THE BRANCHES OF Platonia insignis (CLUSIACEAE). The chemical study of the branches of Platonia insignis enabled the isolation of the biflavonoid morelloflavone and the identification, by mass spectrometry, of over 9 polyphenols, including eight biflavonoids, one benzophenone, and one xanthone. The in vitro biological tests of solar photoprotection and antiradical activities against the crude extract and Hex and AcOEt fractions showed relevant results, which confirm the high pharmaceutical potential of the species.
  • REDUçãO DE CO2 EM HIDROCARBONETOS E OXIGENADOS: FUNDAMENTOS, ESTRATéGIAS E DESAFIOS Revisão

    Silva, Gelson T. S. T. da; Lopes, Osmando F.; Dias, Eduardo H.; Torres, Juliana A.; Nogueira, André E.; Faustino, Leandro A.; Prado, Fernando S.; Patrocínio, Antônio O. T.; Ribeiro, Caue

    Abstract in Portuguese:

    CO2 REDUCTION TO HYDROCARBONS AND OXYGENATES: FUNDAMENTALS, STRATEGIES AND CHALLENGES. The development of renewable energy sources (e.g., solar and wind) moves foward, the tendance for replacing fossil fuels increases. However, these technologies have as primary barriers to industrial processes’ efficiency and especially storage. Thus, CO2 reduction routes using these energy sources could chemically store part of the energy as fuels or chemicals, offering alternatives to current oil and gas industry. This process is inspired by photosynthesis, e.g., photochemical or electrochemical processes, using homogeneous or heterogeneous catalysts. Nevertheless, this reaction is thermodynamically unfavorable and has very slow kinetics, given the high stability of the CO2 molecule and the complexity of the redox reactions involved. Therefore, this review addresses this process’s kinetic and thermodynamic challenges, and the fundamental concepts of the photo(electro)chemical processes for CO2 reduction, besides presenting and discussing the materials with the potential to act as catalysts. The main reaction mechanisms and advances in the understanding of such processes are discussed, as well as future perspectives
  • ENGANANDO O CITOCROMO P450BM3: CATáLISE DE VáRIAS TRANSFORMAçõES DE SUBSTRATOS NãO NATIVOS USANDO MOLéCULAS-TRAIçOEIRAS Revisão

    Stanfield, Joshua K.; Suzuki, Kazuto; Yonemura, Kai; Malewschik, Talita; Shoji, Osami

    Abstract in Portuguese:

    TRICKING CYTOCHROME P450BM3: CATALYSIS OF VARIOUS NON-NATIVE SUBSTRATE TRANSFORMATIONS USING DECOY MOLECULES. In order to accomplish a greener chemistry, enzymes, such as the fatty-acid hydroxylase cytochrome P450BM3, have garnered increasing attention as potential candidates for the development of potent biocatalysts in recent years. However, one of the biggest issues hampering the quick and efficient application of P450BM3 as a biocatalyst lies in its stringent substrate specificity. Consequently, diverse mutagenesis-based approaches have been successfully employed as a means to alter the substrate specificity of P450BM3, leading to the generation of a myriad of highly specialised mutant variants. Nevertheless, repeated exhaustive mutagenesis is a laborious process with no guarantee for success, thus, alternative methods to more easily alter the enzyme’s substrate specificity have become increasingly desirable. In recent years, decoy molecules, which possess the ability to deceive wild-type P450BM3 into hydroxylating a range of non-native substrates, have emerged as such a “simpler” alternative. Within this review, focus will be placed upon the process underlying the development of these decoy molecules, which will be discussed in great detail. Furthermore, a summary of recent developments pertaining to the potential applications of decoy molecules from the development of a whole-cell biocatalyst to their use in crystallography will be discussed.
  • O PROCESSO DE ANODIZAçãO DO ALUMíNIO E SUAS LIGAS: UMA ABORDAGEM HISTóRICA E ELETROQUíMICA Revisão

    Araujo, João Victor de Sousa; Silva, Rejane Maria Pereira da; Klumpp, Rafael Emil; Costa, Isolda

    Abstract in Portuguese:

    THE ANODIZING PROCESS OF ALUMINUM AND ITS ALLOYS: A HISTORICAL AND ELECTROCHEMICAL APPROACH. Al and its alloys are found in several industrial applications. However, like most metals, this material is not immune to corrosion, being necessary to be protected against corrosion. One of the methods most commonly employed to improve the corrosion resistance of Al alloys is the anodizing process, which consists of thickening of the natural oxide (Al2O3) presents in Al through anodic oxidation. The anodizing process is accomplished by immersion of the Al alloy into an acid bath and passing an electric current through it. This process produces two layers: a barrier layer thicker than the natural oxide and a layer with regular arrangement of nanopores (porous layer). This duplex structure forms the anodized layer with a large specific surface area. With the advent of nanotechnology, this layer has been applied in other areas due to its low cost, stability, absence of toxicity, and biocompatibility. In this context, this paper addresses a historical and electrochemical review of the anodizing process of Al and its alloys, presenting the main events that culminated in the development of the current processes and the understanding of the relationship between the chemical reactions and the mechanisms that occur during nucleation and development of the oxide layer.
  • ASPECTOS GERAIS DA QUíMICA DOS DITIOCARBAMATOS E DE SEUS COMPLEXOS METáLICOS E INTERAçõES DESSAS ESPéCIES QUíMICAS COM IMPORTANTES ENZIMAS – UMA BREVE REVISãO Revisão

    Menezes, Daniele C.; Lima, Geraldo M. de

    Abstract in Portuguese:

    GENERAL ASPECTS OF THE CHEMISTRY OF DITHIOCARBAMATES, THEIR METALLIC COMPLEXES AND THEIR INTERACTIONS WITH IMPORTANTE ENZYMES – A BRIEF REVISION. Dithiocarbamates (DTCs) comprise a series of compounds included in the class of 1,1`dithiolates. The application of these organic molecules in the coordination chemistry of some metals is well explored in the last decades, along with their potential applications in medicinal chemistry. In view of our expertise in this field, the syntheses of new DTCS, their coordination chemistry towards various metallic cations and their biocide activities, we summarize in this manuscript the outcomes of some investigations registered in the literature, involving the interactions of DTCs or their complexes with some key enzymes such as carbonic anhydrases, superoxide dismutase, urease, tyrosinase, glutathione, caspases and dehydrogenases. It is provided with a brief introduction of the chemistry of DTCs, electrochemistry, the kinetics of formation, solubility and stability towards solvation. The next topics summarize the results of some experiments concerning the inhibition of these cited enzymes effected by DTCs and some of their coordination complexes. The final remarks and conclusion of the outcomes are provided at the end of the manuscript.
  • TRANSFORMADA INVERSA DE LAPLACE PARA ANáLISE DE SINAIS DE RESSONâNCIA MAGNéTICA NUCLEAR DE BAIXO CAMPO Nota Técnica

    Moraes, Tiago Bueno

    Abstract in Portuguese:

    INVERSE LAPLACE TRANSFORM FOR SIGNAL ANALYSIS OF LOW FIELD NUCLEAR MAGNETIC RESONANCE. The objective of this work is to describe the mathematical procedure denominated ‘Inverse Laplace Transform’ used to process Low Field Nuclear Magnetic Resonance signals of experiments as CPMG, Inversion Recovery and Saturation Recovery. Also, we present a developed script, “ILT Origin script” v.1, in the environment of the software Origin Lab 9 to execute it. The presented ILT is executed with an algorithm of non-negative last square, with Tikhonov regularization and singular values decomposition. The main features of the code were tested using simulated and experimental signals, and in order to validate the results the same sets of data were analyzed using similar ILT softwares. The developed scripts for Origin Lab, Matlab and other languages are available for free for scientific and teaching uses.
  • GURUPI ISOTHERMS PLOT (GIP): UMA FERRAMENTA COM INTERFACE GRáFICA INTUITIVA E GRATUITA COMO ALTERNATIVA PARA O CáLCULO DE PARâMETROS DE ISOTERMA DE ADSORçãO Nota Técnica

    Castro, Douglas A.; Milhomem, Mateus P. S.; Pereira, Douglas H.; Leal, Paulo V. B.

    Abstract in Portuguese:

    GURUPI ISOTHERMS PLOT (GIP): A TOOL WITH INTUITIVE AND FREE GRAPHIC INTERFACE AS AN ALTERNATIVE FOR THE CALCULATION OF ADSORPTION ISOTHERMA PARAMETERS. Gurupi Isotherms Plot (GIP) is a new software and has been developed to facilitate the study of absorptive processes. The adsorption isotherm parameters are determined by the GIP in a non-linearized way, and the current version is implemented to determine the parameters of Langmuir, Freundlich, Dubinin-Radushkevich, coefficient of determination (R2) and average relative error (ARE). In order to facilitate the access and use of the program, a friendly graphical interface has been developed with a response time in seconds. It should also be noted that is a free software. The program was tested with different sets of absorptive data and showed an excellent correlation with the literature data proving its performance.
  • O USO DE SOFTWARES LIVRES EM AULA PRáTICA SOBRE FILTROS MOLECULARES DE BIODISPONIBILIDADE ORAL DE FáRMACOS Educação

    Rodrigues, Gabriela dos Santos; Avelino, Júnior A; Siqueira, Ariane L. N.; Ramos, Luciana F. P.; Santos, Gabriela B. dos

    Abstract in Portuguese:

    THE USE OF FREE SOFTWARES IN PRACTICAL CLASS ABOUT THE MOLECULAR FILTERS OF ORAL BIOAVAILABILITY OF DRUGS. The study of the physical chemical properties to predict the oral bioavailability of drugs is a widely tool used by researches on the Pharmaceutical and Medicinal Chemistry field. Even though it is a deeply studied subject, it is a complex task to teach to pharmacy students. Lipinski stablished that molecular weight, lipophilicity, hydrogen bond donors and acceptors are of great importance for oral bioavailability. In addition, Veber and Lovering added other properties, such as number of rotatable bonds, fraction of sp3 hybridized carbon and polar surface area that amplified the Lipinski Rule of 5. In this sense, the access to chemical databases and the comprehension of this information is an important task to undergraduate and graduate students. Thus, this work aims a new teaching methodology that values the critical interpretation of data and that favors the students comprehension beyond stablished rules.
  • SIMETRIA MOLECULAR E REAçõES DE DESSIMETRIZAçãO EM SíNTESE ORGâNICA Educação

    Paz, Bruno Matos; Lucca Júnior, Emilio C. de; Pilli, Ronaldo A.

    Abstract in Portuguese:

    MOLECULAR SYMMETRY AND DESYMMETRIZATION REACTIONS IN ORGANIC SYNTHESIS. Molecular Symmetry has found several applications in Organic Chemistry. The aim of this article is to showcase its relevance as a tool for synthetic planning. Natural Products and synthetic compounds with pharmaceutical applications were selected to highlight desymmetrization reactions that make use of organocatalysis, biocatalysis or by transition metals. The recognition of structural patterns in retrosynthetic analysis is discussed for compounds that exhibit explicit or hidden symmetry. Limitations of the aforementioned strategies are also described, as well as the untapped potential, challenges and frontiers yet to be explored regarding these concepts.
  • COVERAGE OF INTERMOLECULAR FORCES IN ORGANIC CHEMISTRY TEXTBOOKS Educação

    Silva Júnior, José Nunes da; Oliveira, José Mariano de Sousa; Alexandre, Francisco Serra Oliveira; Leite Junior, Antonio José Mello

    Abstract in English:

    The paper analyzes fifteen organic chemistry textbooks commonly used in Brazilian universities to examine intermolecular forces’ coverage in them. The findings revealed that the intermolecular forces are spread over a few pages (less than 1%) in a fragmented way, and over several chapters that do not provide enough information to help create a clear image in the student’s mind. Thirteen textbooks contained end-of-chapter problems related to intermolecular forces. However, less than 1.3% of the total (212) are associated with intermolecular forces. This deficient approach to intermolecular forces in Organic textbooks can lead to teachers’ lack of interest in teaching the subject, leading to students failing to learn this important organic chemistry topic.
  • A NANOTECNOLOGIA NO BRASIL E O DESENVOLVIMENTO DE PRODUTOS COM ATIVIDADE ANTIMICROBIANA Assuntos Gerais

    Dias, Bruna de Paula; Ribeiro, Erica Milena de Castro; Gonçalves, Ricardo Lemes; Oliveira, Diego Santos; Ferreira, Tiago Hilário; Silva, Breno de Mello

    Abstract in Portuguese:

    NANOTECHNOLOGY IN BRAZIL AND THE DEVELOPMENT OF PRODUCTS WITH ANTIMICROBIAL ACTIVITY. Due to the tremendous technological potential and applicability in various industry branches, nanotechnology investments have been increasing over the years. In particular, the control of microorganisms using nanomaterials with antimicrobial action has aroused great interest in the industry. This control makes it necessary in the most diverse situations, such as food conservation, pharmaceutical industry, hospital environments, and even domestic and commercial environments. This extraordinary interest is due, in particular, to the physical-chemical characteristics of materials on a nanoscale that attributes greater efficiency in combating microorganisms. Therefore, researchers and entrepreneurs have directed investments and efforts towards developing new products and/or new applications for antimicrobial products already existing on the market. In this work, we made a brief presentation of the history of nanotechnology in Brazil with a focus on Brazilian companies that developed products or services with nanomaterials with antimicrobial action, and on the description of some of the existing applications in the Brazilian market, highlighting the productive potential of the parents.
  • O JARDIM VENENOSO: A QUíMICA POR TRáS DAS INTOXICAçõES DOMéSTICAS POR PLANTAS ORNAMENTAIS Assuntos Gerais

    Aguiar, Ana Tayná Chaves; Veiga Júnior, Valdir Florêncio da

    Abstract in Portuguese:

    THE POISONOUS GARDEN: THE CHEMISTRY BEHIND THE INTOXICATION BY DOMESTIC ORNAMENTAL PLANTS. In times of the COVID-19 pandemic, despite the fact families have spent more time together, the job demands and commitments that adults have now brought into their homes may mean their attention has been taken away from their children. This, combined with the absence of older family members or domestic helpers that assist in looking after the children has left them potentially more exposed to domestic accidents. Data from the National Toxic-Pharmacological Information System indicate that two-thirds of domestic intoxications with plants (usually the ornamental ones) occur in children. These accidents can be caused either by inhalation, contact with the skin, eyes and mucous membranes, as well as by ingestion. The toxicity of ornamental plants is due to the presence of substances such as oxalic acid and its highly irritating salts, alkaloids, glycosides, flavonoids, and toxic terpenes, among several other classes of secondary metabolites. In the present study, we carried out a survey of the main ornamental plants used in the country and analyzed the toxic substances that can cause numerous conditions from dermatitis in milder cases to death in more severe cases.
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