Arsenic and Other Elements Determination in Seawater Using Coprecipitation and Standard Mode Inductively Coupled Plasma Mass Spectrometry
The present work aims the determination of As, Co, Cr, Cu, Mn and Pb in seawater samples using coprecipitation extraction procedure before standard mode inductively coupled plasma mass spectrometry (ICP-MS) (no collision/reaction cell). The coprecipitation procedure is based on the precipitation of Mg(OH)2 from the reaction of the Mg2+ ions (present into the seawater) with ammonia added to the sample. Central composite design, desirability function, and response surface methodology were used to optimize the coprecipitation procedure. The optimum values obtained were 1200 µL of aqueous ammonia, 30 min of centrifugatio...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Identification of Two Additional Behaviorally Active Gland Constituents of Female Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)
In this study, two additional female-produced compounds in D. saccharalis eliciting consistent antennal response in males were identified as (Z)-hexadec-9-enal and hexadecanal. In flight tunnel assays, the behavioral response to a quaternary blend was significantly higher when compared with the previously identified binary blend. Subtracting (Z)-hexadec-9-enal or hexadecanal from the full blend did not reduce attraction, indicating redundancy in the communication channel. We conclude that additional compounds are part of the sex pheromone of D. saccharalis, which may improve the efficiency of trap lures for monitoring of t...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Assessment of the Physicochemical Quality Indicators and Microbiological Effects of Brazilian Ozonized Vegetable Oils
The study of quality indicators in the process of obtaining ozonized vegetable oils is useful for monitoring the ozonation reaction. The Brazilian oils “ dend ê ” , soy, corn, rice and sunflower were studied, all of them were ozonated applying different doses of ozone. Ozonized oils were evaluated by determining the physicochemical indexes of peroxide, acidity, iodine and density in addition viscosity, fatty acid composition and microbiological activity were determined. The results showed that of the five ozonized oils evaluated, “ dend ê ” oil exhibited a higher peroxide index, approxim...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Reordering of Depolymerized Silicates as Adsorbents for Large Nitrogen Compounds
The adsorption capacities of two synthesized zeolites (crystalline ZSM-5 and semi-crystalline faujasite Y) for a mixture of indole, quinoline and carbazole were studied. The different samples obtained show different crystalline degree, mesoporosity and Si/Al ratios. The synthesis procedure is based on the simultaneous depolymerization of a mixture of high surface area silica, such as rice hull ashes (RHA), and a crystalline zeolite, such as clinoptilolite or faujasite. The depolymerization step is followed by a partial reorganization induced by a structure-directing agent. A model mixture of nitrogenous compounds was prepa...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

A Facile Synthesized Polyaniline Coated Zerovalent Iron-Silica as an Efficient Sorbent for Magnetic Solid Phase Extraction of Phenolic Pollutants in Water Samples
A magnetic material based on polyaniline coated zerovalent iron-silica (Fe@SiO2@PANI) was simply synthesized using a facile manner under low energy consumption and applied for magnetic solid phase extraction of phenolic pollutants prior to analysis by high performance liquid chromatography-photodiode array detection (HPLC-PDA). The parameters which affected the extraction efficiency, i.e., sorbent amount, extraction time, sample volume and pH, desorption solvent and its volume, were optimized. Wide linear dynamic range of 0.012-10.000 μ g mL-1 and the coefficients of determination better than 0.9926 were achieved. The l...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Reusable Heterogeneous SnO2/ZnO Catalyst for Biodiesel Production from Acidified/Acid Oils
A catalyst comprised of SnO2 impregnated on ZnO nanowires, which presented remarkable ability to catalyze fatty acid esterification/transesterification reactions, is reported. For optimization of reaction conditions, artificially acidified soybean oil with 10 wt.% oleic acid was used as a model feed. The optimized conditions were: 150 °C, 6 h, 5 g of oil, catalyst concentration of 5%, and methanol:oil molar ratio of 15:1. The catalyst achieved 92% of total fatty acid methyl esters (FAME) content and was used five times without the necessity of catalyst washing from one reaction to the other. Then, such conditions were ...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Synthesis, Characterization and Exchange Reactions of Layered Double Hydroxides of Copper and Aluminum, Intercalated with Sulfate
Layered double hydroxides (LDHs) of Cu:Al in the molar ratio of 2:1, intercalated with sulfate, sulfate/(Li+, Na+, K+ or NH4+), NO3- and CO32-, were synthesized by co-precipitation with increasing pH. The materials were submitted to exchange reactions using B2SO4 (B = Li+, Na+, K+, NH4+) solutions in an attempt to replace previously intercalated cations or incorporated cations without removing intercalated sulfate. X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra were consistent with the expected intercalated species and scanning electron microscopy (SEM) images indicated submicrometric platel...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

An Efficient and Recyclable Sn-Based Phosphotungstic Acid with Tunable Br√łnsted/Lewis Acidity for Selective Oxidation of Benzyl Alcohol
A series of metal ion (M = Sn2+, Fe3+, Ni2+, Co2+, Ag+, Cu2+) exchanged tungstophosphoric acid (H3PW12O40; TPA) catalysts with tunable Br ønsted/Lewis acidity were synthesized and exploited for the oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using hydrogen peroxide (H2O2) as oxidant. The structure of these M-TPA composite salts was also characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X RD), thermogravimetric analyses (TGA) and solid-state 31P nuclear magnetic resonance (NMR) probe molecule method. Among these M-TPAs, the Sn1/2H2PW12O40 catalyst, which presented strong...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Brazilian Mineral Clays: Classification, Acid Activation and Application as Catalysts for Methyl Esterification Reactions
In this study, three raw Brazilian clays from Jo ão Pessoa, Paraíba State (Aço AP, AVL and Verde Lodo) were characterized before and after purification and acid activation. Several instrumental techniques were used, and the raw clays were classified as dioctahedral smectites with different compositions, where the AVL sample had the highest cont ent of montmorillonite. In addition, analyses showed modification in clay mineral compositions, mainly due to removal of impurities and octahedral sheet cation leaching during acid activation, which resulted in specific areas ranging from 42 to 93 m2 g-1 and inc...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Interaction of Suspended Particulate Material with Cd2+ and Pb2+ in a Brazilian Lagoon Estuarine System
The suspended particulate material (SPM) present in waters has fundamental importance for a better understanding of environmental behaviors of aquatic pollutants. This work determined the physicochemical parameters (pH, temperature, conductivity, total organic carbon and metals concentration) in water samples from Munda ú-Manguaba estuarine-lagoon system, Alagoas, Brazil. This work extracted and characterized the organic matter present in SPM in this estuary and studied the interaction of this organic matter with potentially toxic metals (Cd2+ and Pb2+). The results of the physical-chemical parameters evaluated sh o...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Evaluation of the Metabolic Profile of Arabica Coffee via NMR in Relation to the Time and Temperature of the Roasting Procedure
Coffee is one of the most popular and consumed products in the world, with high nutritional value and economic importance. However, some factors can change the organoleptic properties of a coffee species, without causing significant damage such as loss of important components. The present study evaluated the chemical profile, via nuclear magnetic resonance (NMR), of the main biological properties and substances of the drink, verifying similarities in the composition of different types of arabica coffee made in different conditions, such as the roasting time and temperature. The main components were identified, using inform...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Automated Framework for Developing Predictive Machine Learning Models for Data-Driven Drug Discovery
The increasing availability of extensive collections of chemical compounds associated with experimental data provides an opportunity to build predictive quantitative structure-activity relationship (QSAR) models using machine learning (ML) algorithms. These models can promote data-driven decisions and have the potential to speed up the drug discovery process and reduce their failure rates. However, many essential aspects of data preparation and modeling are not available in any standalone program. Here, we developed an automated framework for the curation of chemogenomics data and to develop QSAR models for virtual screeni...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent
Five new π -conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the target compounds was performed by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), 13C NMR, thermogravimetric analysis (TGA), absorption and emission spectroscopy techniques. Arylcinnamic acids were obtained as pure E-isomers. On the...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Molecular Modelling Study of Heteroarylamide/Sulfonamide Compounds with Antitrypanosomal Activity
In this study, the quantitative structure-activity relationship (QSAR) were built using partial least squares (PLS) regression, and the results were robust and adequate for predicting and proposing five new derivatives according to the statistical parameters. The docking results suggest that the best-scored HA/S derivatives showed hydrogen bonds with the residuals that comprise the catalytic region of the enzyme. The molecular dynamics (MD) simulations, performed with different methods, revealed the strong stability of the compound obtained by the QSAR model of this study, in addition to a better binding free energy value ...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

o-DGT Devices for the Determination of Emerging Contaminants in Aqueous Matrices
Samplers based on the diffusive gradients in thin films for organics (o-DGT) were developed and applied in Brazilian aqueous matrices for the determination of four emerging contaminants (EC): 4-octylphenol, 4-nonylphenol, triclosan, and bisphenol A. The OASIS HLB resin used as the binding phase presented a high sorption capacity and the extraction associated with sonication, using a mixture of acetonitrile and methanol (2:1, v v-1) as the solvent, provided a higher desorbed mass of the compounds. The diffusion coefficients determined experimentally were in the range of the values found in the literature and the pH and ioni...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Isotopic Analysis of Sugarcane/Petroleum Polyethylene Blends: A Perspective on the Application of Stable Isotope Method (δ13C)
In the present work, we propose the application of stable isotope analysis ( δ 13C) as an auxiliary tool for the inspection of sugarcane/petroleum polyethylene blends. Our results are supported from the analysis of selected samples by accelerator mass spectrometry (14C-AMS). From the results, it was concluded that the δ 13C method is suitable to discriminate samples derived from sugarcane, petroleum, or its blends. It was also noted that both regression models ( δ 13C method and the δ 13C vs 14C-AMS regression) presents potential to estimate the bio-based content; however, future work should focus o...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Study of Inorganic Profiles of Street Cocaine Samples Using ICP-MS and ICP OES
In this study, we analyzed 52 street cocaine samples, seized in three different regions of Esp írito Santo, state of Brazil. Inductively coupled plasma optical emission spectrometry was used to determine Al, Ca, Cu, Fe, Mn, Mg, Zn concentrations and inductively coupled plasma mass spectrometry to determine Mo, Co, Pb and P concentrations. From analyte recovery tests, the accuracy was conside red acceptable and the proposed method satisfactory. Most of the samples exhibited a relatively homogeneous inorganic profile with similar concentrations of investigated elements, however some samples had very discrepant concent...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Synthesis of Antioxidant Additive from Safflower Seed Oil
Several published studies have evaluated the problems associated with the utilization of biodiesel obtained from safflower (Carthamus tinctorius L.) oil due to the low oxidative stability, caused by the high content of unsaturated fatty acids. Thus, this study aimed at the extraction of safflower seed oil and its use as an unsaturation source to obtain a synthetic antioxidant. The synthesis of this phenolic additive was done by modifying its structure through the addition of hydroquinone to the unsaturation of the oil, by electrophilic substitution. It was investigated and confirmed that this reaction is promising for obta...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Evaluation of Lignins of Trunk and Roots from Citrus sinensis L. Osbeck: A Large Available Brazilian Biomass
Citrus biomass is a source of biobased products and presents extensive chemical diversity. Among the structural macromolecules, lignins have been used in resins, bioplastics, and nanoencapsulation. Brazil has a large source of lignins, which are orange trees removed from groves that need to be renewed. However, the knowledge about these lignins is limited and little explored. Thus, this work aimed to evaluate the lignins from Citrus sinensis and to provide information on the interesting use of orange trees as a source of macromolecules. The lignins were isolated from the trunk, central and secondary roots from the orange t...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Optimization of the Reaction Conditions for the Synthesis of Dihydrobenzofuran Neolignans
We have optimized the experimental conditions for the silver(I)-promoted oxidative coupling of methyl p-coumarate (I) and methyl ferulate (II), which is the most frequently used methodology to synthesize the bioactive dihydrobenzofuran neolignans 1 (( ±)-trans-dehydrodicoumarate dimethyl ester) and 2 ((±)-trans-dehydrodiferulate dimethyl ester). Most of the tested conditions affected the conversion (i.e., the consumption of I and II) and the selectivity (i.e., the percentage of I and II that was converted into 1 and 2, respectively), so the opt imized conditions were the ones that afforded the best balance be...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Speciation of Antimony in Injectable Leishmanicidal Drugs by Lowering Citric Acid Concentration Used in Hydride Generation Atomic Absorption Spectrometry Analysis
This study proposes a procedure for speciation of antimony by hydride generation atomic absorption spectrometry in pentavalent antimony drugs. The SbIII content was determined by selective generation of SbH3 in medium with higher SbV concentration using 4 to 20-fold lower citric acid solutions than recommended in the available literature. The multivariate optimization of the methods was performed through factorial design followed by a central composite design (CCD). The limit of detection (LOD) and limit of quantification (LOQ) were calculated at 0.15 and 0.05 µg L-1 and 0.48 and 0.17 µg L-1, for total Sb and S...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Direct Solid Sample Analysis of Medicinal Herbs for Determination of Ba, Cu, Ni, V and Zn by EDXRF
In this work, an analytical method for determination of Ba, Cu, Ni, V, and Zn, in medicinal herbs, through direct solid sample analysis by energy dispersive X-ray fluorescence spectrometry (EDXRF), was applied. Accuracy and precision (intra and inter day) of the analytical method were confirmed through analysis of certified reference material, tomato leaves (CRM NIST 1573a). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed to observe the formation of two groups. Group I was composed by highest levels of Cu and Zn, and the group II with highest concentrations of Ba, V, and Zn. Group I also ...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

What to Expect for the New Year?
(Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Additions and Corrections
This work describes the isolation of pure bergenin from Peltophorum dubium roots with good yields and its further derivatization through Williamson synthesis. The alkyl derivatives of the bergenin were identified by nuclear magnetic resonance and mass spectrometry data analysis. Among them, three derivatives were reported for the first time herein, 8,10-dihexyl-bergenin, 8,10-didecyl-bergenin, and 8,10-ditetradecyl-bergenin, along with three previously reported ones (8,10-dimethylbergenin, 8-methylbergenin, 8,10-dioctyl-bergenin). Most derivatives of the bergenin displayed moderate cytotoxicity against Artemia salina, exce...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Bergenin of Peltophorum dubium (Fabaceae) Roots and Its Bioactive Semi-Synthetic Derivatives
This work describes the isolation of pure bergenin from Peltophorum dubium roots with good yields and its further derivatization through Williamson synthesis. The alkyl derivatives of the bergenin were identified by nuclear magnetic resonance and mass spectrometry data analysis. Among them, three derivatives were reported for the first time herein, 8,10-dihexyl-bergenin, 8,10-didecyl-bergenin, and 8,10-ditetradecyl-bergenin, along with three previously reported ones (8,10-dimethylbergenin, 8-methylbergenin, 8,10-dioctyl-bergenin). Most derivatives of the bergenin displayed moderate cytotoxicity against Artemia salina, exce...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Identification of Potential Inhibitors of Severe Acute Respiratory Syndrome-Related Coronavirus 2 (SARS-CoV-2) Main Protease from Non-Natural and Natural Sources: A Molecular Docking Study
So far, there is neither a vaccine nor a specific antiviral drug to prevent or treat COVID-19 (coronavirus disease) infection. Recent studies have been done to investigate the capacity of human immunodeficiency virus type 1 (HIV-1) protease inhibitors be used in the treatment of COVID-19 patients. Some of those drugs have shown to be promising. Natural chemical substances from plants provide a good source of chemicals for the development of potential novel antiviral drugs against viral pathogens including HIV-1. In January 2020, a new promising target useful for structure-based drug design was elucidated and stored in the ...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Multifunctionality of βCD/Ofloxacin and HPβCD/Ofloxacin Complexes: Improvement of the Antimicrobial Activity and Apoptosis Induction on Lung Adenocarcinoma A549 Cells
The ofloxacin (OFLOX) is a second-generation synthetic antibiotic that can be classified as a multifunctional drug, but is a poorly soluble drug, which influences its efficiency. The inclusion complexes of OFLOX with β -cyclodextrin ( β CD) or hydroxypropyl- β -cyclodextrin (HP β CD) can improve the chemical characteristics of the drug; however, studies showing the biological activity of these inclusion complexes are still scarce. The present work aimed to investigate the multifunctionality of the OFLOX and their inclusion complexes. Thus, the 1:1 β CD/OFLOX or HP β CD/OFLOX were prepared and ...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

An Electrochemiluminescence Biosensor for the Determination of Mercury Ion via Dual-Amplification Strategy
A novel dual-signal amplificatory electrochemiluminescence (ECL) deoxyribonucleic acid (DNA) biosensor was designed for the determination of Hg2+. One amplification unit was gold nanoparticles (AuNPs) modified on a glassy carbon electrode, and the other was single-stranded DNA (ssDNA) (with amino at the 3 ’ terminal and thiol at the 5 ’ terminal) labeled with a carboxyl-functionalized Ru@SiO2 nanoparticles (Ru1@SiO2) as a nanoprobe. The ECL biosensor was obtained through a strong gold-sulfur bond between Au on AuNPs modified electrode and thiol in the nanoprobe. In the presence of Hg2+, the ECL signal reduced b...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Activated Complex Approach to Describe Bovine Serum Albumin-Azure A and Bovine Serum Albumin-Azure B Intermolecular Interactions
Azure A (AZA) and azure B (AZB) phenothiazine dyes are used for clinical and medical purposes, and their functions can be altered via interactions with proteins. However, no kinetics information on the interactions between phenothiazine dyes and bovine serum albumin (BSA) is available. Surface plasmon resonance was used to determine the energetic and dynamic of the BSA-AZA and BSA-AZB complexes formation at pH 7.4. At temperature ≤ 16 °C, the formation of activated (DH ‡ a,12 °C,AZA= -310.57 kJ mol-1 and DH ‡ a,12 °C,AZB= -256.37 kJ mol-1) and thermodynamically stable (DH°12°C,AZA= -314...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Green Extraction Optimization of Bioactive Compounds from Rosemary (Rosmarinus officinalis L.) Using Response Surface Methodology
Rosemary (Rosmarinus officinalis L.) is known for its bioactive compounds with high antioxidant potential and pharmacological properties, such as antibacterial, antidepressant and anti-inflammatory. These properties are attributed to the presence of (poly)phenolic compounds. In the literature there is no extraction of these compounds with a totally non-toxic solvent, capable of applying the extract directly to the food. This work aimed to optimize the extraction conditions of bioactive compounds from the rosemary leaves using water as solvent. According to the analysis of variance parameters, a cubic model of high order of...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Synthesis, in silico Study and Antimicrobial Activity of New Piperine Derivatives Containing Substituted δ-Esters
A series of fifteen new piperine-derived diesters was synthesized through the substitution reaction between the salt of piperic acid, obtained through piperine basic hydrolysis, with the δ -chloro-esters, obtained through the cleavage of tetrahydrofuran (THF) with acyl chlorides in the presence of ZnCl2. The final compounds were obtained with yields ranging from 50 to 84% and were characterized by infrared (IR) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR). The new compounds were evaluated in silico in regard to their ADME (absorption, distribution, metabolism, and excretion) properties, and in vitro f...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Method for Cleaning Back-Produced Water from Polymer Flooding Operations to Determine Polymer Molar Mass Using Size-Exclusion Chromatography
One of the methods used by the oil industry to increase production is to inject water, containing polymer, into the reservoir. The viscosity of the aqueous solution is primarily responsible for the efficiency of this method, and is achieved using polymers with high molar mass. However, polymer degradation can occur during pumping and fluid displacement in the porous medium, reducing the efficiency of the polymer flooding method. Therefore, it is important to monitor the molar mass of the polymer in the produced water. Size-exclusion chromatography (SEC) is a powerful method for determining average molar mass of polymers, b...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Synthesis and Antioxidant and Antimicrobial Properties of β-Hydroxy Sulfides, Sulfoxides, and Sulfones Derived from Cardanol and Glycerol Derivatives
This article reports the preparation of amphiphilic β -hydroxy sulfides, sulfoxides, and sulfones derived from cardanol and glycerol. Thiolysis of cardanol epoxide 3 with various thiols (4a-4j) in ethanol or water yielded the corresponding β -hydroxy sulfides 5a-5j (61-95%). Treatment with 30% H2O2 in acetic acid at ambient temperature completely converted these products into β -hydroxy sulfoxides 6a-6j and sulfones 7a, 7c-7f, 7h-7j. The synthesized compounds were characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, high-resolution mass spectroscopy (HRMS) and performed the in vitro evaluation anti...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Development of a First-Order Derivative UV Spectrophotometric Method for the Assay and Solubility Evaluation of Lamotrigine and Nicotinamide Cocrystals
Pharmaceutical cocrystals are composed of a drug and a coformer and are currently gaining attention due to their possibility of improving drug solubility. Quantitative determination of cocrystals is usually carried out by liquid chromatography method, but an alternative for the same is derivative UV spectrophotometry. Cocrystals of lamotrigine (LAM) were formed with nicotinamide (NIC) in order to improve the solubility of LAM. The aim of this study was to develop and validate a simple, low-cost, environment friendly, first-order derivative spectrophotometric method for simultaneous determination of LAM and NIC in cocrystal...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Determining Mercury in Sediment Samples by Extraction Using a Novel-Chelating Reagent Dithiothreitol (DTT) Followed by Cold Vapor Atomic Fluorescence Spectrometry (CV-AFS)
A new analytical protocol has been developed for the determination of mercury in surface sediments using dithiothreitol (DTT) as a new chelating reagent for the extraction. This protocol requires a small sample mass (250 mg), 4.0 mL of a 0.1 M (pH = 9.0) aqueous DTT solution, and sonication for 30 min, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). The limits of detection and quantification determined were 6 and 18 ng g − 1, respectively. The method was validated using three standard reference materials, SRM NIST 1646a, PACS-2, and MESS-3, with recoveries in the range of 102-124%. The new analytica...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Identification of Flavonoids as Inhibitors of Plasmodium falciparum Enoyl-ACP Reductase by Hierarchical Virtual Screening
Malaria, a parasitic infection caused by Plasmodium falciparum, is a serious global public health problem. The enzyme enoyl-acyl carrier protein (ACP) reductase present in a limiting step in the biosynthesis of fatty acids type II was used to search for novel molecules with potential inhibitor by virtual screening techniques. A flavonoid library obtained in ChEMBL database (n = 4,008) was filtered through physico-chemical similarity using the Euclidean distance as a criterion. The selected molecules were subjected to molecular docking using the scoring function GridScore in the DOCK 6.5 software. The top 30 ranked molecule...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

NMR in Analysis of the Nutritional Value of Lipids from Muscles and Livers of Wild Amazonian Fishes with Different Eating Habits Over Seasonal Variation
Endogenous and environmental factors can influence the lipid contents of fishes among which, in the Amazon River, seasonal dynamics influences stand out. Herein, nine most consumed Amazonian fish species had their lipid composition evaluated in terms of effects of tissue, season and eating habits. Higher amounts of lipids were obtained from fish livers than dorsal muscles. Statistical analysis has shown that Amazonian fishes presented different lipid profiles according to their eating habits, which mainly comprised saturated fatty acids to distinguish detritivorous livers, and linolenic acid, cholesterol, polar lipids for ...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Multiresidue Determination of Endocrine Disrupting Compounds in Sewage Treatment Plants (SPE-HPLC-DAD)
This work focuses on the validation and application of solid phase extraction followed by high-performance liquid chromatography (SPE-HPLC) analysis of important endocrine disruptors compounds (EDC) from different classes in highly complex wastewater matrix. The endocrine disruptors investigated included three different categories: pharmaceuticals (sulfamethoxazole (SMZ), trimethoprim (TMP) and diclofenac (DCF)), hormones (estrone (E1), 17 α -ethinylestradiol (EE2) and 17 β -estradiol (E2)) and plastic materials (bisphenol A (BPA)). The method involves pre-concentration by SPE using Strata-X extraction cartridge...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Evaluation of Dog Food Authenticity through Lipid Profile Using GC-FID and ESI-MS
Considering the increasing number of low cost vegetable oil product adulterations, it is necessary to assess the authenticity of the lipid sources used in the dog food manufacture, consequently different brands and classifications of feed were analyzed to verify the product authenticity by gas chromatography (GC) with flame ionization detector (FID) and by electrospray ionization mass spectrometry (ESI-MS). Fatty acid (FA) composition analysis was performed to compare the FAs amount in samples with the respective guarantee levels stated by the manufacturers on its product label. Gas chromatography with flame ionization det...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Synthesis of 1,2,3-Triazole Derivatives of Hydnocarpic Acid Isolated from Carpotroche brasiliensis Seed Oil and Evaluation of Antiproliferative Activity
Carpotroche brasiliensis is a tree native to Brazil, belonging to the family Flacurtiaceae, whose seeds contain a group of cyclopentenyl fatty acids: gorlic (12%), chaulmugric (27%), and hydnocarpic (48.7%). These compounds are considered the main therapeutic agents in the treatment of leprosy. In the present study, a series of novel triazole compounds were obtained by conjugation between hydnocarpic acid and functionalized azides via copper(I)-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Hydnocarpic acid and its derivatives were tested against estrogen-positive breast carcinoma (MCF-7), hepatocellular carcinoma ...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Optimization of Methodology for Determination of Inorganic Chromium Species in Sewage Sludge Samples by HPLC-ICP-MS/MS
This study developed a methodology for extracting and speciating CrIII and CrVI in sewage sludge by high performance liquid chromatography, inductively coupled plasma tandem mass spectrometry (HPLC-ICP-MS/MS). The optimal procedure was solid-liquid extraction in a water bath with stirring at 50 °C for 16 h and 50 mmol L − 1 ethylenediaminetetraacetic acid (EDTA) extraction phase at pH 9.5. In the validated method, the recovery in the fortification experiment was greater than 70% and the relative standard deviation was less than 7%. Speciation analyses showed that all CrVI was spontaneously reduced to CrIII in the...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Determination of Total Antioxidant Capacity Using Thiamine as a Natural Fluorescent Probe
This work proposes a spectrofluorometric method for the determination of total antioxidant capacity (CAO) in beverage samples, based on inhibition of thiochrome formation ( λ ex = 370 nm, λ em = 440 nm); a product of thiamine (vitamin B1) oxidation from K3Fe(CN)6. In the development of the method, gallic acid (GA) was used as a reference, and inhibition of thiochrome formation (in percentage) was used as the analytical response. The selectivity of the method was evaluated using seven different compounds (gallic acid, ascorbic acid, quercetin, butylhydroxytoluene (BHT), 6-hydroxy-2,5,7,8-tetramethylchroman-2 (...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

X-ray Scattering and Chemometrics as Tools to Assist in the Identification of Gunshot Residues by Wavelength Dispersive X-ray Fluorescence Spectrometry
Wavelength dispersion X-ray fluorescence spectrometry (WDXRF) is a non-destructive technique and therefore attractive for gunshot residues (GSR) analysis. It is well known for determination of inorganic constituents of samples. However, X-ray scattering region spectral data is not commonly used, although it may provide information about organic constituents and their interactions. This work employed X-ray scattering region and inorganic elements spectral data for a better characterization of GSR. Swabs containing residues collected from the hand of people who fired (shooters group) and also from the hands of people which d...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

A Straightforward Synthesis of Enantiopure (1S,2R)-Ephenamine
An enantioselective six-step synthesis of (1S,2R)-ephenamine starting from readily available chiral amino acid is disclosed presenting 26% overall yield and high optical purity. The use of chiral phenylglycine as starting material was also studied and did not present satisfactory results due to a very sensitive a-carbonyl/benzylic stereogenic center that, in our hands, led to racemization. (Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Application of Nickel Ferrite Nanoparticles in Adsorption of Amoxicillin Antibiotic
According to the World Health Organization, amoxicillin (AMX) is the most widely consumed antibiotic in the world. Consequently, there is great interest in the development of new technologies that allow the removal of this type of contaminant, as exposure to antibiotic residues can cause a variety of adverse effects, such as toxicity and antimicrobial resistance. In this work, AMX adsorption from aqueous solution was investigated using nickel ferrite nanoparticles. The nanoadsorbents were prepared by the coprecipitation method, annealed at 300 to 700 °C, and characterized by X-ray diffraction (XRD), transmission electr...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Calibration Strategies Applied to Laser-Induced Breakdown Spectroscopy: A Critical Review of Advances and Challenges
Over the years, laser-induced breakdown spectroscopy (LIBS) has been reported in the literature as an alternative to traditional methods of analysis, becoming well established among spectroanalytical techniques. LIBS is a technique widely used for qualitative approaches; however, it is necessary considerable effort for use in quantitative analysis, mainly due to severe matrix effects. These limitations make it difficult to broaden the application of LIBS in quantitative analysis. In this sense, this review discusses recent advances in calibration strategies applied in LIBS for minimizing matrix effects and enabling determi...
Source: Journal of the Brazilian Chemical Society - December 14, 2020 Category: Chemistry Source Type: research

Blue-Emitting MWO4:Tm3+ (M: Sr, Ba) Phosphors Prepared by Coprecipitation Method at Room Temperature
MWO4 host matrices (M: Sr, Ba) doped with different Tm3+ concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 mol%) have been successfully prepared by the coprecipitation method at room temperature. The as-prepared nanophosphors were characterized by infrared spectroscopy showing intense absorption bands in the range of 700-1000 cm-1 attributed to the symmetrical and asymmetrical stretching vibrations ( ν ) of the tetrahedral [WO4]2- group. The X-ray diffraction (XRD) measurements reveal the tetragonal scheelite phase with the I41/a (No. 88) space group. The emission spectra of the MWO4:Tm3+ materials are dominated by the hi...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Sunlight-Driven Dehydrogenative Oxidation Photocatalysis by a Mononuclear Complex Acting as both Chromophore and Catalyst
Under simulated solar irradiation in the visible spectral region, the catalytically active RuIV-oxo species [Ru(O)(bpy)(tppz)]2+ (tppz = tetrapyridylpyrazine, a strongly π -accepting tridentate N, N, N-ligand) is produced directly from a single metal-to-ligand charge-transfer (MLCT) photoexcitation of the resting RuII-aquo complex [Ru(H2O)(bpy)(tppz)]2+ in aqueous media containing an electron acceptor. This photoinduced path to 2-electron/2-proton activation of a mononuclear catalyst (i.e., without a paired chromophoric unit) is enabled by the thermodynamic instability of the intermediate RuIII-hydroxo species [Ru(OH)(b...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Photoluminescent Investigation of the Doping Site of Eu3+-Doped [Zn3(BTC)2·12H2O] Metal-Organic Framework Prepared by Microwave-Assisted Hydrothermal Synthesis
The [Zn3(BTC)2 ·12H2O] (BTC = 1,3,5-tricarboxylate) metal-organic framework (MOF) was successfully synthesized using a microwave-assisted hydrothermal synthesis technique, which allowed for significantly decreased reaction time compared to the production of the same compound via conventional heating. In situ dopi ng with Eu3+ ions at concentrations ranging from 1.0 to 5.0 mol% produced doped materials whose emission ranged from blue to red color. The Eu3+ spectroscopic properties were used to study the incorporation of the dopant into the structure of [Zn3(BTC)2·12H2O], even at very low concentrations. Thes e...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Synergistic Supramolecular Effect on the Electro-Oxidation of Biological Relevant Molecules: A Novel Sensor for Simultaneous Determination of Epinephrine and Uric Acid in Human Urine Using MWCNT and a Copper(II) Complex
In this paper a novel supramolecular strategy to improve the efficiency of a voltammetric sensor to determine two biologically relevant molecules (epinephrine (EP) and uric acid (UA)) is presented. The strategy is based on the use of a glassy carbon electrode modified with a copper(II) complex ([Cu(H2dimpy)Cl]PF6) adsorbed on multi-walled carbon nanotubes (MWCNTs). The [Cu(H2dimpy)Cl]PF6/MWCNT composite-supported electrode was characterized by electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrocatalytic oxidation of EP and UA using the sensor was ...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research