Editorial Lopes, Norberto Peporine |
Artigo Volatile compounds profile and flavor analysis of yerba mate (Ilex paraguariensis) beverages Machado, Carla Carolina Batista Bastos, Deborah Helena Markowicz Janzantti, Natália Soares Facanali, Roselaine Marques, Marcia Ortiz M. Franco, Maria Regina Bueno Abstract in English: Volatile compounds from green and roasted yerba mate were analyzed by gas chromatography/mass spectrometry and the flavor profile from yerba mate beverages was determined by descriptive quantitative analyses. The main compounds tentatively identified in green mate were linalool, alpha-terpineol and trans-linalool oxide and in roasted mate were (E,Z)-2,4-heptadienal isomers and 5-methylfurfural. Green mate infusion was qualified as having bitter taste and aroma as well as green grass aroma while roasted mate was defined as having a smooth, slightly burnt aroma. The relationship between the tentatively identified compounds and flavor must be determined by olfatometric analysis. |
Artigo Total mercury in mangrove soils of the Baixada Santista and Cardoso Island, São Paulo state Oliveira, Mara Lucia Jacinto Vidal-Torrado, Pablo Otero, Xosé Luis Ferreira, José Roberto Abstract in English: Total Hg content in soils of Baixada Santista, affected by different sources of pollution, and Cardoso Island, which is almost free of anthropogenic activities, were determined by CVAAS. To explain the fate of Hg in the ecosystem, pH, Eh, AVS, Stotal and Total Organic Carbon were also obtained throughout the soil profiles. With the exception of two sampling sites the average content of Hg in samples obtained for Baixada Santista was 0.34 ± 0.20 mg kg-1, which was close to the average data at Cardoso Island (0.30 ± 0.21 mg kg-1). Both of them were below the limit established by CETESB - 0.50 mg kg-1. |
Artigo Alkaloids from flowers and leaves of Erythrina speciosa Andrews Faria, Terezinha de Jesus Cafêu, Mariana Carrara Akiyoshi, Gisele Ferreira, Dalva Trevisan Galão, Olívio Fernandes Andrei, César Cornélio Pinge Filho, Phileno Paiva, Manoel Ronaldo Carvalho Barbosa, Aneli de Melo Braz-Filho, Raimundo Abstract in English: In vitro bioassays with leave extracts of Erythrina speciosa showed promising activity against Trypanosoma cruzi. From the flowers of E. speciosa two alkaloids were isolated: erysotrine and erythartine. The leaves furnished one alkaloid, nororientaline. The structures were determined on the basis of spectroscopic evidence. This is the first report about the investigation of alkaloids in flowers and leaves of this species, as well the first report of nororientaline occurrence in this plant. |
Artigo Chemisorption of divalent cations on a silica gel surface modifield with thioglycolic acid: pH influence and ionic strength Sousa, Kaline S. de Augusto Filha, Vera Lúcia S. Pinto, Victor Hugo e A. Fonseca, Maria G. da Espínola, José G. P. Arakaki, Luiza N. H. Abstract in English: A novel type of heavy metal adsorbent was prepared by the covalent grafting of thioglycolic acid molecules on a silica gel surface previsiouly modified with 3-aminopropyltrimethoxysilane. The amount of thioglycolic acid immobilized was 1.03 mmol per gram of silica. This material displayed a chelating moiety containing nitrogen, sulfur, and oxygen basic centers which are potentially capable of extracting from aqueous solutions cations such as Cu(II), Ni(II), Co(II), influenced by pH and ionic strength. This process of extraction was carried out by the batch method when similar chemisorption isotherms were observed for all cations. A modified Langmuir equation describes the experimental data. |
Artigo Optimization and validation af liquid-liquid extraction with the low temperature partition technique (LLE-LTP) for pyrethroids in water and GC analysis Vieira, Heulla Pereira Neves, Antônio Augusto Queiroz, Maria Eliana Lopes Ribeiro de Abstract in English: The liquid-liquid extraction with the low temperature partition technique was developed for the analysis of four pyrethroids in water by CG. Using a factorial design the extraction technique was optimised evaluating the effect of the variables ionic strength, contact time and proportion between sample and solvent volumes. The validation parameters sensitivity, precision, accuracy and detection and quantification limits were evaluated. The LOD and LOQ of the method varied from 1.1 to 3.2 µg L-1 and 2.7 to 9.5 µg L-1, respectively. |
Phase diagram and complex patterns in the modeling of the bromate-oxalic acid-Ce-acetone oscillating reaction Pereira, Janaina A. M. Faria, Roberto B. Abstract in English: Simulations have been carried out on the bromate - oxalic acid - Ce(IV) - acetone oscillating reaction, under flow conditions, using Field and Boyd's model (J. Phys. Chem. 1985, 89, 3707). Many different complex dynamic behaviors were found, including simple periodic oscillations, complex periodic oscillations, quasiperiodicity and chaos. Some of these complex oscillations can be understood as belonging to a Farey sequence. The many different behaviors were systematized in a phase diagram which shows that some regions of complex patterns were nested with one inside the other. The existence of almost all known dynamic behavior for this system allows the suggestion that it can be used as a model for some very complex phenomena that occur in biological systems. |
Artigo Statistical design of experiments as a tool for optimizing the batch conditions of Cu(II) biosorption using pecan nutshells as biosorbent Brasil, Jorge L. Vaghetti, Júlio C. P. Royer, Betina Santos Jr, Araci A. dos Simon, Nathalia M. Pavan, Flávio A. Dias, Silvio L. P. Lima, Eder C. Abstract in English: In order to reduce the total number of experiments for achieving the highest amount of adsorbed Cu2+ (qmax) using pecan nutshells (Carya illinoensis) as biosorbent, a full 2(4) factorial design with two central points was carried out (mass of biosorbent- m, pH, initial metallic ion concentration- C0, time of contact- t). In order to continue the optimization of the system, a central composite surface analysis design with two factors and five central points was carried out. The maximum amount of Cu2+ taken up by the pecan nutshells was 20 mg g-1. These results were confirmed by determining a Cu2+ isotherm using the best conditions attained by the statistical design of experiments. |
Artigo Distribution of selenium in marine organisms from Guanabara Bay/ RJ Seixas, Tércia Guedes Moreira, Isabel Kehrig, Helena do Amaral Malm, Olaf Abstract in English: The study assessed selenium concentrations in the muscle tissues and liver samples of three fish species and in the soft tissues of a mussel species. The samples were analyzed by GF-AAS using Zeeman background correction. Selenium in the muscle samples was higher in carnivorous fish. The liver of all studied fish species presented higher selenium concentrations than the muscle. The fish species presented a high positive correlation between their total length and selenium concentration. A significant correlation was observed between the selenium concentration in the mussel soft tissues and the condition index. |
Artigo Utilization of solid-phase extraction (SPE) for the determination of polycyclic aromatic hydrocarbons in environmental aqueous matrices Cavalcante, Rivelino M. M. Filho, Nilton S. Viana, Rommel B. Oliveira, Isadora R. N. Nascimento, Ronaldo F. Silveira, Edilberto R. Freire, George S. S. Abstract in English: Polycyclic aromatic hydrocarbons (PAHs) are a great environmental concern mainly because of their toxic, mutagenic and carcinogenic potential. This paper reports utilization of the solid-phase extraction (SPE) technique to determine PAHs in environmental aqueous matrices. The recovery from environmental aqueous matrices fortified with PAHs varied from 63.7 to 93.1% for atmospheric liquid precipitation, from 38.3 to 95.1% for superficial river water, and from 71.0 to 95.5% for marine water. No negative matrix effect was observed for the recovery of PAHs from atmospheric liquid precipitation and marine water, but was observed for superficial river water, particularly for PAHs possessing 5 and 6 aromatic rings. |
Artigo Evaluation of environmental contamination by persistent organic pollutants utilizing simulation of leach processes Pinto, Glaucia Maria F. Pinto, Jefferson Ferreira Maciel Filho, Rubens Abstract in English: Environmental concern is growing in the current days and there is global agreement to banish production and use of persistent organic pollutants (POP). The synthetic insecticides chlordecone and mirex, classified as POPs, have similar structures and they are potentially toxic. This work uses properties and physicochemical constants related to the pesticides and computational simulation to evaluate the leach phenomenon and persistency in soil. The largest tendency of persistence of the compound is found to be in the surface of soil, but even low concentration in water represents a high risk due to bioaccumulation in adipose tissue. |
Artigo Study of different forms of phosphorus in the Amazon continental shelf waters Santos, Maria de Lourdes Souza Muniz, Kátia Feitosa, Fernando Antonio do Nascimento Barros Neto, Benício de Abstract in English: Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes. |
Artigo Use of EDTA disodium salt as standard for preparation of solutions Silva, Paulo H. Pereira da Oliveira, Andrea Medeiros, Lívia Soman de Neves, Eduardo F. de Almeida Abstract in English: The hydrated sodium salt of EDTA, Na2H2Y·2H2O, cannot be used as a primary standard for titrations due to uncertainties in the water content. An alkalimetric titration of the homogenized solid in the presence of a small excess of BaCl2·2H2O allows one to titrate quantitatively the released two hydrogen cations with end-point indication by phenolphthalein or potentiometry. This leads one to calculate the average molar mass of the reagent and its water content, allowing to use it to prepare EDTA standard solutions. One titrated sample led to the formula Na2H2Y·1.876 H2O, and 370.01 g.mol-1 for the average molar mass. |
Artigo Polycyclic aromatic hydrocarbons as sugarcane burning tracers: a statistical approach Magalhães, Dulce Bruns, Roy E. Vasconcellos, Pérola de Castro Abstract in English: In this study atmospheric particulates of PAHs were measured in Araraquara, Piracicaba and São Paulo in July 2003 (sugarcane harvest season in Araraquara and Piracicaba) and in Araraquara in March of 2003. The results were normalized to the total PAH concentrations. Comparison among the sites and principal component analysis (PCA) were used to investigate possible tracers of emission. Fluoranthene and pyrene concentrations were higher in Piracicaba and Araraquara samples. These PAH were also responsible for the largest negative loadings on the second principal component and account for the negative scores and for the formation of the Araraquara and Piracicaba group. |
Artigo Evaluation of concentration of some metal ions in different lichen species of the Sul-Mato-Grossensse cerrado Raposo Junior, Jorge Luiz Ré-Poppi, Nilva Honda, Neli Kika Abstract in English: Concentrations of Fe, Mn, Co, Cr, Zn and Cu were determinated using flame atomic absorption spectrometry in nine lichen species of the Sul-Mato-Grossense cerrado. The average metal ion concentrations varied in the following ranges: Fe, 248.41-1568.01; Mn, 98.50-397.33; Co, 10.08-24.81; Cr, 18.24-44.26; Zn, 14.62-34.79 and Cu, 3.23-7.57 mg kg-1. Statistical analysis (Pearson and Cluster) applied to the metal ion concentrations indicated that the accumulation of these ions can be due to several anthropogenic sources including agricultural activities, mineral exploration, biomass burning, soil mineral composition and leather tanning processes by chromium. |
Artigo Determination of zinc in soil using colorimetry Fraige, Karina Crespilho, Frank Nelson Rezende, Maria Olímpia Oliveira Abstract in English: In terms of soil fertility, zinc is a micronutrient that is very important in the culture of soy, maize, rice and coffee, because it is a structural and functional component of a great number of enzymes. Therefore, diverse methods have been used to determine zinc in soil. In this work we use colorimetry as a methods of zinc determination in soil using two methodologies of sample digesting, H2SO4/H2O2 and HNO3/H2O2. In order to compare the results, atomic absorption spectrometry (AAS) was used. Results show that colorimetric methods can be used due to good sensitivity and reproducibility, since the zinc calibration curve showed good linearity. Comparing colorimetric methods with AAS we observed that the results were equivalent, as proven by the statistical values of the F and t of Student tests. Furthermore, both methods of soil digesting can be used, leading to a flexible methodology of low-cost for routine zinc analyses in soil. |
Artigo Influence of deproteinizing acids in erythrocytic reduced glutathione quantification by HPLC-UV Schott, Karen L. Charão, Mariele F. Valentin, Juliana Cassol, Juniara Garcia, Solange C. Pomblum, Valdeci J. Bohrer, Denise Abstract in English: Large differences in reduced glutathione (GSH) levels have been found in different investigations, also in healthy people. GSH oxidation in vitro has been associated with sample acidification in the presence of oxihemoglobin. In this work, the influence of different acids on GSH determination utilizing HPLC with UV detection was evaluated. The results showed that metaphosphoric acid and sulfosalicylic acid were inadequate for analysis, because metaphosphoric acid showed to be inefficient for deproteinization and with sulfosalicylic acid loss of GSH was observed. Trichloroacetic acid did not effect GSH quantification, since the deproteinized form was immediately derivatized with 5, 5´-dithio-bis (2-nitrobenzoic) acid. Methods with TCA deproteinization presented linear results from 0.5 to 3.0 mM. The correlation coefficient between aqueous curves and GSH spiked RBC exceeded 0.99. Precision calculations showed CV lower than 10% and bias within ± 10% for concentrations of 0.5; 1.5 and 3.0 mM GSH. The recovery was higher than 94%. Moreover, GSH blood concentrations were independent of hemoglobin concentrations. |
Artigo Polar phenolic constituents from Schinus terebinthifolius Raddi (Anacardiaceae) Ceruks, Melina Romoff, Paulete Fávero, Oriana A. Lago, João Henrique G. Abstract in English: The EtOH extract from the leaves of Schinus terebinthifolius showed anti-radicalar potential in the DPPH test. It was partitioned between n-BuOH:H2O (1:1) and these two phases were also evaluated for anti-radicalar activity. The active n-BuOH phase was partitioned between EtOAc:H2O (1:1) and the active EtOAc phase was submitted to chromatographic procedures to afford five active phenolic compounds: ethyl gallate, methyl gallate, quercitrin, myricetrin and myricetin. The structures of these compounds were established by NMR spectral data analysis. |
Artigo Biodiesel from babassu (Orbignya sp.) synthesized via ethanolic route Lima, José Renato de Oliveira Silva, Rondenelly Brandão da Silva, Carmem Cícera Maria da Santos, Lucas Samuel Soares dos Santos Jr., José Ribeiro dos Moura, Edmilson Miranda Moura, Carla Verônica Rodarte de Abstract in English: Biodiesel was obtained by transesterification of babassu oil in anhydrous ethanol and methanol, employing NaOH as catalyst. The products obtained were characterized by physico-chemical and thermogravimetric analysis. It could be concluded that the properties of the two types of biodiesel (ethanolic and methanolic) are very similar when compared with diesel oil. |
Artigo Influence of processing and roasting on the antioxidant activity of cofee (Coffea arabica) Santos, Marcelo Henrique dos Batista, Bruno Lemos Duarte, Stella Maris da Silveira Abreu, Celeste Maria Patto de Gouvêa, Cibele Marli Cação Paiva Abstract in English: The aim of this work is to evaluate the influence of processing (semi-dry and dry) and roasting (light, medium and dark) on the antioxidant activity of coffee brews, using tests to determine the reducing power and the DPPH scavenging, Fe+2 chelating and lipid peroxidation inhibition activities. All of the coffee brews presented concentration-dependent antioxidant activity. The light coffee samples presented the higher reducing power and DPPH scavenging activity. Its ion chelating capacity was similar to the medium samples, but was less than the green coffee chelating capacity. The semi-dry processing was more efficient than the dry processing only for the reducing power. All of the samples presented high lipid peroxidation inhibition activity. Based on the results the degree of coffee roasting seems to be more important than the processing to determine the antioxidant activity of brews. |
Artigo The selective catalytic reduction of no over copper-containing hematite Ferreira, Hadma Sousa Oliveira, Soraia Jesus Rangel, Maria do Carmo Urquieta-González, Ernesto A. Martins, Leandro Garcia Fierro, José Luís Marchetti, Sérgio G. Abstract in English: The activity of copper-doped hematite in the SCR with propane, in the presence of oxygen, was evaluated in this work. It was found that copper sulfate led to the production of solids with different specific surface areas depending on the amount of copper. The sulfur and copper species were mainly located on the surface. The copper-containing catalysts were more active in the reduction of nitrogen oxides and less active in the propane oxidation as compared to pure hematite. This behavior was assigned to an association of both sulfur and copper species to produce new sites active for NO reduction. |
Revisão Carotenoids: properties, applications and biotransformation in flavor compounds Uenojo, Mariana Maróstica Junior, Mário Roberto Pastore, Gláucia Maria Abstract in English: Carotenoids are widely distributed in nature, providing yellow, orange or red color in a great number of vegetables, microorganisms and in some animals. Carotenoids act as biological antioxidants and seem to play an important role in human health by protecting cells and tissues from the damaging effects of free radicals and singlet oxygen. Several authors describe the oxidative cleavage of carotenoids in flavor compounds as occuring through chemical or photochemical degradations or through biotechnological processes. Biotransformation of carotenoids seems to be a reasonable alternative to produce flavor compounds since these compounds are considered 'natural' ingredients. In this work we describe the properties of some carotenoids, as well as biotechnological approaches to obtain its oxyfunctionalized derivatives. |
Revisão Mechanism and applications of the fenton reaction assisted by iron-reducing phenolic compounds Aguiar, André Ferraz, André Contreras, David Rodríguez, Jaime Abstract in English: The mechanism and applications of the Fenton reaction assisted by iron-reducing phenolic compounds (IRPC) is reviewed. The presence of IRPC leads to the formation of a larger number of free radicals. The relationship between the redox potential and the IRPC structure is discussed. The effect of humic substances in the degradation of xenobiotics is also included, since these substances are able to reduce metallic ions. The natural occurrence of Fe3+/H2O2/IRPC in wood biodegradation processes, as well as their application is also discussed. The review concludes with the advantages of the Fe3+/H2O2/IRPC systems and some considerations for further process optimization and their applications at industrial levels. |
Revisão Brominated phenols as key flavor compounds found in marine organisms Silva, Vilma Mota da Lopes, Wilson Araújo Andrade, Jailson B. de Veloso, Márcia C. da Cunha Santos, Gislaine Vieira dos Oliveira, Aline S. Abstract in English: The perception of the flavor is an important attribute of quality in marine fish and other seafoods, being the first and main factor of discrimination for the evaluation, later acceptance and preference of the product by the consumer. Recently, the simple bromophenols have been considered an important group of key flavor compounds occurring in a wide variety of seafood species like fishes, mollusks, crustaceans and algae. When present in high concentration, in seafood, the bromophenols produce an undesirable flavor and are associated with inferior quality. Meanwhile, when present in low concentration levels (for example ng g-1) these compounds produce a desirable marine - or ocean-like - flavor and enhance the existing flavor in seafood. Indeed, simple bromophenols are widespread in seafood but virtually absent in freshwater fish. Herein we present a review on these flavor components found in the marine environment. |
Revisão Synthesis of liquid crystalline block copolymers Coelho, Maria Rita Guinancio Gomes, Ailton de Souza Abstract in English: The principal techniques for the synthesis of liquid crystalline block copolymers are reviewed. The syntheses are done by living/controlled free radical chain polymerization. The copolymers display an amorphous continuous phase and a discontinuous liquid crystalline phase (LC). The presence of oxypropylenic segments disturbs the range of mesophase transitions at lower temperatures. This behavior is not observed when styrenic segments are employed and suggests that the liquid crystalline behavior can be modified in block copolymers to show mesophases at higher and lower temperatures according to the flexibility of the chain segment that is present. |
Revisão Extraction, structures and properties of alpha- AND beta-chitin Campana-Filho, Sergio P. Britto, Douglas de Curti, Elisabete Abreu, Fernanda R. Cardoso, Marcia B. Battisti, Marcos V. Sim, Priscilla C. Goy, Rejane C. Signini, Roberta Lavall, Rodrigo L. Abstract in English: The fact that alpha- and beta-chitin adopt different arrays in the solid state is explored to emphasize their different properties and distinct spectral characteristics and X ray diffraction patterns. The methods for their extraction from the biomass in view of the preservation of their native structures and aiming to fulfill the claims of purity and uniformity for potential applications are discussed. The different arrays adopted by alpha- and beta-chitin also result in distinct reactivities toward the deacetylation reaction. Thus, the deacetylation of beta-chitin is more efficient owing to the better accessibility to amide groups due to the lower crystallinity of this polymorph. |
Revisão Endocrine disrupters in the enviroment: part 1 - effects and consequences Bila, Daniele Maia Dezotti, Márcia Abstract in English: There is an increasing interest in micropollutants in the environment that can interfere with the endocrine system, affecting health, growth and reproduction of animals and humans. These substances are known as Endocrine Disrupting Chemicals (EDCs) and can be found in domestic sewage, domestic wastewater treatment plant effluents, and in natural and potable waters. There are numerous chemicals classified as EDCs, such as pesticides, chemicals used and produced by chemical industries and natural and synthetic estrogens. EDCs can be related to the increase of the incidence of anomalies in the reproductive system of animals, cancer in humans and reduction of the masculine fertility. |
Revisão Transformation of triglycerides into fulels, polymers and chemicals: some applications of catalysis in oleochemistry Suarez, Paulo A. Z. Meneghetti, Simoni M. Plentz Meneghetti, Mario R. Wolf, Carlos R. Abstract in English: The use of biomass as raw-material for obtaining chemicals, polymers and fuels is emerging as a clever alternative solution for the increasing energy demand, environmental awareness and petroleum shortage. In this work, some attempts in order to develop catalytic systems suitable for triglyceride transformation into fuels, polymers and intermediates are reviewed. |
Seeing smells: development of an optoelectronic nose Suslick, Kenneth S. Bailey, Daniel P. Ingison, Crystal K. Janzen, Michael Kosal, Margaret E. McNamara III, William B. Rakow, Neal A. Sen, Avijit Weaver, Jeremy J. Wilson, Jennifer B. Zhang, Chen Nakagaki, Shirley Abstract in English: The development of an array of chemically-responsive dyes on a porous membrane and in its use as a general sensor for odors and volatile organic compounds (VOCs) is reviewed. These colorimetric sensor arrays (CSA) act as an "optoelectronic nose" by using an array of multiple dyes whose color changes are based on the full range of intermolecular interactions. The CSA is digitally imaged before and after exposure and the resulting difference map provides a digital fingerprint for any VOC or mixture of odorants. The result is an enormous increase in discriminatory power among odorants compared to prior electronic nose technologies. For the detection of biologically important analytes, including amines, carboxylic acids, and thiols, high sensitivities (ppbv) have been demonstrated. The array is essentially non-responsive to changes in humidity due to the hydrophobicity of the dyes and membrane. |
Divulgação Nomenclature for comprehensive multidimensional chromatography in portuguese language von Mühlen, Carin Zini, Cláudia Alcaraz Caramão, Elina Bastos Abstract in English: Comprehensive Multidimensional Chromatography is a relatively new analytic technique, which is receiving growing attention in many parts of the world, including recently in Brazil. This work presents terms in Portuguese which are commonly used in Comprehensive Multidimensional Chromatography in order to help standardize the vocabulary employed in this area in the scientific literature. It also includes some symbols, their nominations, and explanation of some terms, whenever necessary. This proposal does not intend to be comprehensive or definitive; on the contrary, it intends to be a first step in the process of establishing a standardized nomenclature, serving as a base for a further sound discussion in the scientific community realm. |
Divulgação Groundwater contamination by pesticides: preliminary evaluation Ribeiro, Maria Lúcia Lourencetti, Carolina Pereira, Sueli Yoshinaga Marchi, Mary Rosa Rodrigues de Abstract in English: A discussion about groundwater contamination is presented in this work. Contamination by agricultural activity, more specifically by pesticides is emphasized. Indirect and direct estimates could be used to predict pesticide behavior in soil, and consequently, to evaluate the potential of groundwater contamination. These results could be applied to advise about the possibility of groundwater contamination by pesticides, and to provide subsidies for making decisions more quickly and efficiently. |
Divulgação Endocrine disruptors in the enviroment Ghiselli, Gislaine Jardim, Wilson F. Abstract in English: Although the hypothesis that environmental chemicals may exhibit endocrine disrupting effects is not new, the issue has been a growing level of concern due to reports of increased incidences of endocrine-related disease in humans, including declining male fertility, and more significantly, to adverse physiological effects observed in wildlife where cause and effect relationships are more evident. The list of endocrine disrupting chemicals (EDCs) includes a range of anthropogenic compounds, phytoestrogens, naturally occurring sex steroids and synthetic estrogens. Within the aquatic environment, the presence of EDCs has concerned many scientists and water quality regulators. Discharge of effluents from treatment facilities is likely to be a significant source of input of contaminants to many systems, and the potential for concentration of hydrophilic compounds and transformation products within sludges has implications for their disposal. Then, understanding the processes and the fate of EDCs on the environment, as well as the mechanisms of endocrine disruption, may facilitate controlling or limiting exposure of both humans and the environment to these compounds. |
Physicochemical parameters of Amazon Melipona honey Almeida-Muradian, Ligia Bicudo de Matsuda, Adriana Hitomi Bastos, Deborah Helena Markowicz Abstract in English: Stingless bees produce a honey that is different from the Apis honey in terms of composition. There aren't enough data to establish quality control parameters for this product, mainly due to lack of research results. The aim of this work is to evaluate some physicochemical parameters that can be used for the characterization and for the quality control of the Meliponinae honey. Four different samples were collected in the Amazon region of Brazil in 2004 (Melipona compressipes manaoense bee and Melipona seminigra merribae bee). Honey analyses were performed as described by the official methods. The mean results were: moisture (30.13%), pH (3.65), acidity (24.57 mEq/kg), water activity (0.75), fructose (31.91%), glucose (29.30%) and sucrose (0.19%). These results reinforce the need for a specific regulation for stingless bee honey. This will only be feasible when enough data is available to establish upper and lower limits for the physicochemical parameters used for quality control. |
Nota técnica Ascarel determination in insulating oil of transformers Antonello, Izoldir Humeres, Eduardo Souza, Ivan Gonçalves de Debacher, Nito Angelo Martins, Alexandre Rios Abstract in English: The contamination level of silicon oil used as insulation liquid in high-voltage transformers by ascarel (PCBs) is above those permitted by the Brazilian law. Thus new techniques able to detect ascarel, with low operational costs, are very attractive. The present work proposes an analysis of the contamination levels of silicon oil using the following techniques: naphthalene anion radical reaction for ascarel dechlorination; and potentiometry with an ion-selective electrode for chloride ion determination. The data obtained with the proposed methodology agree well with those from the official methodology, (method IEC 61619). |
Nota técnica Recovery of cadmium from nickel-cadmium batteries via selective extraction with tributylphosphate (TBP) Barandas, Ana Paula Mauro Gonçalves Valverde Jr, Ivam Macedo Afonso, Júlio Carlos Mantovano, José Luiz Cunha, José Waldemar Silva Dias da Abstract in English: This work describes a recovery process of cadmium from spent nickel-cadmium batteries by a new hydrometallurgical route based on the selective extraction in hydrochloric acid medium with tributylphosphate (TBP), alone or dissolved in kerosene. The best results were obtained when TBP concentration was at least 75 vol%. Nickel extraction was negligible under these conditions. It was isolated after processing the rafinate through an anionic ion-exchange column. Final wastes generated are basically sodium chloride solutions, with no turbidity, color or heavy metals present in significant amounts. |
Nota técnica Processing of the spent Li/MnO2 battery Paulino, Jéssica Frontino Busnardo, Natália Giovanini Afonso, Julio Carlos Abstract in English: This work presents two recycling processes for spent Li/MnO2 batteries. After removal of the solvent under vacuum the cathode + anode + electrolyte was submitted to one of the following procedures: (a) it was calcined (500 ºC, 5 h) and the calcined solid was submitted to solvent extraction with water in order to recover lithium salts. The residual solid was treated with sulfuric acid containing hydrogen peroxide. Manganese was recovered as sulfate; (b) the solid was treated with potassium hydrogeno sulfate (500 ºC, 5 h). The solid was dissolved in water and the resulting solution was added dropwise to sodium hydroxide. Manganese was recovered as dioxide. The residual solution was treated with potassium fluoride in order to precipitate lithium fluoride. |
Educação Synthesis of the iron(II)-nitrogen complex: concepts of reactivity and back-bonding for undergraduate chemistry students Pissetti, Fábio L. Nonô, Rogério S. Gushikem, Yoshitaka Dias, Gilson H. M. Abstract in English: There has been a considerable interest in coordination complexes of molecular nitrogen (N2), partly due to a possible relationship between such complexes and the nitrogen activation process in nature. The present paper describes the synthesis and infrared spectroscopic characterization of an iron-nitrogen derivative with ethylenediamine-N,N,N',N'-tetraacetate (edta) as an experiment for an undergraduate course. The topics covered here include synthesis, reactivity and spectroscopy. |
Educação Reactivity in Diels-Alder reactions: a computational experiment Lacerda Júnior, Valdemar Oliveira, Kleber Thiago de Silva, Rodrigo Costa e Constantino, Mauricio Gomes Silva, Gil Valdo José da Abstract in English: A computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally observed reactivity order. NBO - Natural Bond Orbitals - analysis was used to ascertain the effect of C=C substituents on the dienophile reactivity. |
Educação Case studies in chemistry Sá, Luciana Passos Francisco, Cristiane Andretta Queiroz, Salete Linhares Abstract in English: The case-study method of instruction is increasing in popularity and instructors of various scientific disciplines are adopting this method for their courses. Its effectiveness suggests that there is a need for such resources to be used in chemistry education. In this paper we describe this method in detail and present our use of cases in a scientific communication course offered to undergraduate chemistry students at the University of São Paulo. The description of the method and the example of its use may be helpful for faculty members who wish to explore new ways to engage students more deeply in their learning and to reinvigorate their own teachig practice. |
Assuntos gerais Terminologia para as técnicas analíticas de eletromigração em capilares Silva, José Alberto Fracassi da Coltro, Wendell Karlos Tomazelli Carrilho, Emanuel Tavares, Marina Franco Maggi Abstract in English: This is a contribution that presents a translation of the work "Terminology for Analytical Capillary Electromigration Techniques" by Riekkola and collaborators (Pure Appl. Chem., Vol. 76, No. 2, 443-451, 2004) from IUPAC© for the Portuguese Language. Additional terms that had not been defined in native Portuguese were included for the benefit of the local community. Additional notes were also included to clarify some important concepts and to highlight the differences between techniques. |
Assuntos gerais The plasticity of non-crystalline solids: aluminum phosphate white pigments Galembeck, Fernando Silva, Maria do Carmo V. M. da Rosseto, Renato Abstract in English: A new white pigment made out of nano-structured non-crystalline aluminum phosphate was recently launched as an industrial product. Pigment opacifying properties are not intrinsic to aluminum phosphate but they arise as the result of a rare hollow particle nano-structure. This is in turn derived from the core-and-shell structure of amorphous aluminum phosphate precipitated under well-defined conditions. The new pigment is a product of the often neglected chemistry of non-crystalline ionic solids that can probably be a rich source of new successful products. The text describes a short account of the R&D activities, from the initial ideas to the present. |
Eduardo J. S. Vichi Chagas, Aécio P. Pilli, Ronaldo A. Gushikem, Yoshitaka |