Química Nova, Volume: 31, Issue: 5, Published: 2008
  • SBQ 2006-2008 Editorial

    Mangrich, Antonio Sálvio; Lopes, Norberto Peporine
  • Production of dry material and grains by bean plants (Phaseolus vulgaris L. ) cultivated in soils treated with heavy metals Artigo

    Carvalho, Alexandre Vitor Santana de; Carvalho, Ruy; Abreu, Celeste Maria Patto de; Furtini Neto, Antônio Eduardo

    Abstract in English:

    This work aimed at evaluating the contents of extractable Cd, Pb, Zn and Cu with a solution of DTPA (diethyleneaminopentacetic acid) and to relate them with the production of dry material and grain production of bean plants under two conditions of experimentally contaminated soil materials with Cd, Pb, Cu and Zn: (i) samples of distrofic red latosol and (ii) humic yellow-red latosol. A decrease in the yield of dry matter was observed for all treatments, if compared with the zero-dose control sample; the grain yield was affected for the soil samples treated with Cd and Cu but only slightly for those treated with Pb and Zn.
  • Fatty acid profile and evaluation of alteration of frying oils Artigo

    Corsini, Mara da Silva; Jorge, Neuza; Miguel, Ana Maria Rauen de Oliveira; Vicente, Eduardo

    Abstract in English:

    The present study had the purpose of evaluating the profile of fatty acids and the total alteration of cottonseed, sunflower and palm oils brought about during discontinued frying processes of cassava frozen chips. An increase in the percentage of saturated fatty acids and a decrease in polyunsaturated fatty acids was observed, regardless of the type of oil used. With regard to the oil's global alteration, the results showed that palm oil, the most saturated one, underwent less alteration. However, none of the oils presented total polar compound values above the limits prescribed.
  • Ceramic nanocomposites from the hight-energy mechanical milling process Artigo

    Carreño, Neftalí L. V.; Garcia, Irene T. S.; Santos, Luís P. S.; Fabbro, Maria T.; Keyson, Dawy; Leite, Edson R.; Longo, Elson; Fajardo, Humberto V.; Probst, Luiz F. D.

    Abstract in English:

    Pb/Ti, Sn and Mg-based nanocomposite materials were prepared by the high-energy mechanical milling of commercial powders. The surface of these ceramic compounds was strongly influenced by the doping, diameter of the milling spheres and time of the mechanical milling (amorphization process). Such milling leads to the formation of nanocrystalline materials. The mechanical processing parameters of these compounds were investigated through Brunauer, Emmett and Teller isotherms, wide angle X-ray diffraction, transmission electron microscopy and CO2 adsorption.
  • Development and validation of an analytical method for simultaneous determination of fixed-dose combination tablets of lamivudine, zidovudine and nevirapine by hight performance liquid chromatography Artigo

    Lavra, Zênia Maria Maciel; Rolim Neto, Pedro José; Silva, Rosali Maria Ferreira da; Medeiros, Flávia Patrícia Morais de

    Abstract in English:

    An analytical method has been developed and validated for the quantitation of lamivudine, zidovudine and nevirapine in the fixed-dose combination film-coated tablet by high performance liquid chromatography, in accordance with RE No. 899/2003, National Sanitary Surveillance Agency. It was based on an isocratic elution system with a potassium phosphate buffer pH 3.0: acetonitrile (60:40 v/v) mobile phase, C18, 250 x 46 mm column, 10µm particle size, λ 270 nm. The statistically evaluated results have shown that the method is specific, precise, accurate, and robust, ensuring the analytical safety of 3TC, AZT and NVP determination, which emerges as a new therapeutic alternative for antiretroviral treatment.
  • Simultaneous determination of arsenic, cadmium and lead by GF AAS in purified water samples for hemodialysis after multivariate optimization based on factorial design Artigo

    Santos, Lisia Maria G. dos; Gonçalves, Jaylei M.; Jacob, Silvana do Couto

    Abstract in English:

    This paper reports the development of a methodology for simultaneously determining As, Cd and Pb, employing GF AAS with polarized Zeeman-effect background correction. In order to make the procedure applicable, the influence of pyrolysis and atomization temperatures and the amount of chemical modifiers were studied. Factorial and central composite designs were used to optimize these variables. Precision and accuracy of the method were investigated using Natural Water Reference material, Nist SRM 1640. Results are in agreement with certified values at the 95% confidence limit when the Student t-test is used. This methodology was used for quality control of purified water for hemodialysis.
  • Thermal yield and emission of atmospheric contaminants from gasolines formulated with ethanol, MTBE and TAEE Artigo

    Silva, Rosângela da; Menezes, Eliana Weber de; Cataluña, Renato

    Abstract in English:

    The specific consumption and carbon monoxide (CO) and nitrogen oxide (NO) emissions from gasolines formulated with ethanol, methyl tert-butyl ether (MTBE) and tert-amyl ethyl ether (TAEE) were evaluated in the rich, stoichiometric and lean-burn regions during the operation of an Otto-cycle engine. The use of ethanol as an additive presented high specific consumption, while gasoline formulated with TAEE showed low specific consumption with the engine operating under lean-burn conditions. The ethers evaluated here presented a low percentage of CO in the rich-burn region when compared with ethanol.
  • Study on the use of red mud for removal of dyes from textile effluents Artigo

    Silva Filho, Ernesto Batista da; Alves, Maria Cristina Moreira; Motta, Maurício da; Oliveira, Eveline Haiana da Costa; Brander Junior, Walter

    Abstract in English:

    Red mud is the principal residue of the alumina (Al2O3) industry. Generated during the Bayer process, it is characterized by strong alkalinity and ion exchange. Iron oxides are the principal component (30 to 60%). Annually millions of tons of red mud are generated in the world. Red mud disposal is responsible for a large part of the cost of alumina production. On the other hand, textile industry wastewaters containing dyes have a great impact on the environment and on human health. In this paper the possibility of applying red mud for the removal of dyes was investigated by two processes: adsorption and degradation by the Fenton reagent.
  • Chemical alterations and nickel phytoavailability in sewage sludge-amended soil

    Alvarez V., Felipe Carlos; Boaretto, Antonio Enedi; Abreu Junior, Cassio Hamilton; Muraoka, Takashi; Trevizam, Anderson Ricardo; Fernandes, Henriqueta Maria Gimenes

    Abstract in English:

    The alteration of soil chemicals and its influence on availability (DTPA extractant method) and phytoavailability (63Ni L-value, isotopic method) of Ni was studied in sewage sludge-amended soil at different pHs. The soil pHs were 4.3, 5.3 and 5.9 and the rates of sewage sludge (SS) 0, 15, 30, 45 and 60 Mg ha-1. The chemical and physicochemical soil characteristics were altered by the SS rate and increased the Ni availability and phytoavailability. The isotopic method (63Ni L-value) was more efficient in predicting the Ni phytoavailability that the Ni-DTPA extractant in soil pHs 5.3 and 5.9.
  • Can affinity interactions influence the partitioning of glucose-6-phosphate dehydrogenase in two-phase aqueous micellar systems?

    Lopes, André M.; Pessoa-Jr., Adalberto; Rangel-Yagui, Carlota de O.

    Abstract in English:

    In this work, we provide an investigation of the role and strength of affinity interactions on the partitioning of the glucose-6-phosphate dehydrogenase in aqueous two-phase micellar systems. These systems are constituted of micellar surfactant solutions and offer both hydrophobic and hydrophilic environments, providing selectivity to biomolecules. We studied G6PD partitioning in systems composed of the nonionic surfactants, separately, in the presence and absence of affinity ligands. We observed that G6PD partitions to the micelle-poor phase, owing to the strength of excluded-volume interactions in these systems that drive the protein to the micelle-poor phase, where there is more free volume available.
  • Synthesis of the Ceramic Pigment Victoria Green (Ca3Cr2Si3O12) from CaCO3, Cr2O3 and SiO2 Artigo

    Della, Viviana Possamai; Junkes, Janaina Accordi; Rambo, Carlos Renato; Hotza, Dachamir

    Abstract in English:

    The synthesis of the ceramic pigment Victoria Green (Ca3Cr2Si3O12 ) is described. As raw materials CaCO3, Cr2O3, and SiO2 obtained from rice husk were used. Borax was used as mineralizer. Raw materials were formulated stoichiometrically and calcined from 1000 to 1200 ºC for 180 min. The main phase detected was uvarovite with particle size below 45 mm. The pigments were applied on ceramic tiles and sintered at 1150 ºC for 40 min. The synthesis process showed to be adequate to produce the green pigment, whose characteristics resemble those of a commercial pigment.
  • Organic markers of sewage contamination in surface sediments from Santos bay, São Paulo Artigo

    Martins, César de Castro; Gomes, Fernanda Boechat Azeredo; Ferreira, Juliana Aureliano; Montone, Rosalinda Carmela

    Abstract in English:

    Organic markers, such as sterols and ketones, were used to assess sewage contamination in sediments from the Santos Bay, SP, and its continental shelf. These compounds were analyzed by GC/FID after soxhlet extraction, clean up and derivatization. The concentration of coprostanol and ratios between selected sterols were used to evaluate fecal contamination. The stations located in the mid-western part of the Santos Bay presented organic matter from sewage due to the input of fecal material from the city of Santos by submarine sewage outfall. Stations located at the continental shelf did not present fecal contamination. Coprostanol levels in sewage outfall stations were higher in comparison to other Brazilian coastal areas, except Guanabara Bay/RJ, and could be related to the fraction of the population without sewage treatment.
  • Purification and characterization of a gentiohexaose obtained from botryosphaeran by partial acid hydrolysis Artigo

    Silva, Iara Ribeiro; Monteiro, Nilson Kobori; Martinez, Paula Felippe; Izeli, Nataly Lino; Vasconcelos, Ana Flora Dalberto; Cardoso, Marilsa de Stefani; Silva, Maria de Lourdes Corradi da; Barbosa, Aneli de Melo; Dekker, Robert F. H.; Silva, Gil Valdo José da; Moraes, Luís Alberto Beraldo de

    Abstract in English:

    A hexa-oligosaccharide was obtained by partial acid hydrolysis from botryosphaeran, an exopolysaccharide (EPS) β(1→3; 1→6)-D-glucan type, produced by the ascomyceteous fungus Botryosphaeria rhodina. The oligosaccharide was purified by gel filtration and charcoal-Celite column chromatography and the analysis was followed by HPAEC/PAD. The structure was determined by NMR spectroscopy and mass spectrometry, which showed that the oligosaccharide consists of six β-D-glucopiranosyl units O-6 substituted (gentiohexaose).
  • Cd phytoavailability in sewage sludge-amended soil of different pH estimated by an isotopic method and chemical extraction

    Alvarez Villanueva, Felipe Carlos; Boaretto, Antonio Enedi; Abreu Junior, Cassio Hamilton; Muraoka, Takashi; Trevizam, Anderson Ricardo; Nascimento Filho, Virgilio Franco do

    Abstract in English:

    The Cd phytoavailability in sewage sludge-amended soils of different pHs using the 109Cd L-value isotopic method and Cd extracted by DTPA has been determined. Maize plants (Zea mais L.) were grown under greenhouse conditions in a xanthic ferralsol at different pHs amended with five sewage sludge (SS) rates, and labeled with 74 kBq kg-1 of 109Cd. The SS rates altered the properties of the soil chemicals and these influenced the isotopic parameter (L-value) and percent of Cd uptake by plants from soil (%Cdpdfs) and SS (%CdpdfSS). L-values and Cd extracted by DTPA correlate significantly with SS rates and Cd uptake by plants and are efficient for predicting the Cd phytoavailability in the sewage sludge-amended soil.
  • Synthesis of glycosyl-amino acids of biological interest Artigo

    Campo, Vanessa Leiria; Carvalho, Ivone

    Abstract in English:

    This work describes the synthesis of the glycosylated amino acids αGlcNAc-Thr, βGlcNAc-Thr and αLacNAc-Thr by the glycosylation reaction of the amino acid threonine with the corresponding glycosyl donors αGlcNAcCl and αLacN3Cl. The glycosylated amino acids containing the sugar units α-D-GlcNAc and α-D-LacNAc O-linked to threonine amino acids are related to O-glycans found in mucins of the parasite Trypanosoma cruzi, while the corresponding β-D-GlcNAc isomer is involved in cellular signaling events.
  • Dextrans in lugars from São Paulo State Artigo

    Aquino, Francisco Wendel Batista de; Franco, Douglas Wagner

    Abstract in English:

    The characterization of dextran in sugars by size exclusion chromatography (SEC) has been carried out according to the number-average molecular weight (Mn), the weight-average molecular weight (Mw), the Z-average molecular weight (Mz), and the polydispersity (Mw/Mn). The results suggest that all the analyzed thirty sugar samples from São Paulo state were contaminated with two or three different dextran polymers. The collected data clearly point out that the total dextran content together with the mass distribution parameters Mw, Mn, Mz, and Mw/Mn should be considered during the evaluation of the quality of the sugar used for the cachaça sweeting process.
  • Bioprocesses for removal of carbon dioxide and nitrogen oxide by microalgae for the utilization of gas generated during coal burning Artigo

    Morais, Michele Greque de; Costa, Jorge Alberto Vieira

    Abstract in English:

    The aim of this work was to study the removal of CO2 and NO by microalgae and to evaluate the kinetic characteristics of the cultures. Spirulina sp. showed µmax and Xmax (0.11 d-1, 1.11 g L-1 d-1) when treated with CO2 and NaNO3. The maximum CO2 removal was 22.97% for S. obliquus treated with KNO3 and atmospheric CO2. The S. obliquus showed maximum NO removal (21.30%) when treated with NO and CO2. Coupling the cultivation of these microalgae with the removal of CO2 and NO has the potential not only to reduce the costs of culture media but also to offset carbon and nitrogen emissions.
  • Effect of the radiolitic sterilization in polyethylene/starch blends

    Ferreira, Flávia Gonçalves Domingues; Lima, Maria Alice Gomes de Andrade; Almeida, Yêda Medeiros Bastos de; Vinhas, Glória Maria

    Abstract in English:

    Samples of LDPE/modified starch blends 80/20 m/m before and after exposure to gamma rays were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The effect of gamma radiation is clearly seen in the samples irradiated at a dose of 25 kGy. The main alteration in the polymeric material after exposure at the radiation range was a decrease in the mechanical properties, alterations in the chemical structure of the blend with an increase in the carbonyl and vinyl indices and the appearance of new crystalline symmetry generating a crystalline domain not existing before in the blend.
  • Preparation and characterization of activated carbon produced from coffee waste Artigo

    Brum, Sarah Silva; Bianchi, Maria Lucia; Silva, Vanésia Liane da; Gonçalves, Maraísa; Guerreiro, Mário César; Oliveira, Luiz Carlos Alves de

    Abstract in English:

    Coffee fruit processing is one of the most polluting activities in agriculture due to the large amount of waste generated in the process. In this work, coffee parchment was employed as precursor for the production of carbons activated with ZnCl2 (CAP). The material was characterized using N2 adsorption/desorption at 77 K, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The material showed a surface area of 521.6 m²g-1 and microporous structure. CAP was applied as adsorbent for the removal of methylene blue dye in aqueous medium. The adsorption capacity was found to be about 188.7 mg g-1.
  • Quantification of TBHQ (terc butyl hydroquinone) and oxidative stability evaluation of commercial sunflower oils Artigo

    Masuchi, Monise Helen; Celeghini, Renata Maria dos Santos; Gonçalves, Lireny Aparecida Guaraldo; Grimaldi, Renato

    Abstract in English:

    Sunflower oil is one of the vegetable oils most susceptible to oxidative reaction. Therefore the presence of natural (tocopherol) and/or synthetic (TBHQ) antioxidants is a prerequisite to secure the stability of this oil during its shelf life, especially with the increased use of PET packaging. On determining the total tocopherol content in 10 samples of deodorized sunflower oils, high losses in total tocopherol during deodorization were identified. In order to facilitate researche involving oxidative stability of vegetable oils, a method for isolated quantification of TBHQ using the isocratic elution system was developed.
  • Dipole-dipole operator in angular momentum basis: a complementary study in nuclear magnetic resonance Artigo

    Sebastião, Rita de Cássia de Oliveira; Braga, João Pedro

    Abstract in English:

    The relationship between the magnetic dipole-dipole potential energy function and its quantum analogue is presented in this work. It is assumed the reader is familiar with the classical expression of the dipolar interaction and has basic knowledge of the quantum mechanics of angular momentum. Except for these two points only elementary steps are involved.
  • Determination of biodiesel raw materials in mineral diesel fuel using selective ion monitoring Artigo

    Rocha, Daniel de Queiroz; Barros, Diana Kelly; Costa, Everton José Cardoso; Souza, Katiuscia S. de; Passos, Raimundo R.; Veiga Junior, Valdir Florêncio da; Chaar, Jamal da Silva

    Abstract in English:

    The selective ion monitoring acquisition mode in mass spectrometry was applied to identify, in the diesel complex matrix, the raw materials (vegetable oil and alcohol) that originate biodiesel. Biodiesel samples obtained from babassu, castor, palm and soybean vegetable oils and pure fatty acid methyl and ethyl esters were used to develop this method, using specific fragments in mass spectrometry and the "window system" in gas chromatography. The commercial Brazilian B2 samples were found to be produced with soybean oil, transesterified with methanol.
  • Electrochemical behavior of N-nitrosothiazolidine carboxilic acid on gold and mercury electrodes Artigo

    Codognoto, Lucia; Reyes, Felix G. R.; Winter, Eduardo; Rath, Susanne

    Abstract in English:

    The electrochemical behavior of N-nitrosothiazolidine carboxylic acid (NTAC) on gold and hanging mercury electrodes, using the cyclic and square wave voltammetries, was studied. Whereas NTAC suffer reduction in a single step on the mercury electrode, two peaks appears on the cyclic voltammograms on the gold electrode, one anodic peak overlaying the gold oxide process at 1.2 V and one cathodic peak at -0.41 V vs Ag/AgCl, KCl 3.0 mol L-1. The cathodic peak depends on the previous oxidation of NTAC at the electrode surface, presents irreversible and adsorption controlled characteristics and it is suitable for quantitative purposes.
  • Application of the factorial design and response surface methodology for optimization of alcoholic fermentation Artigo

    Silva, José Alexsandro; Damasceno, Bolívar Ponciano Goulart de Lima; Silva, Flávio Luiz Honorato da; Madruga, Marta Suely; Santana, Davi Pereira de

    Abstract in English:

    In the present work, the influence of the amount of nitrogen and phosphorus and degrees Brix on the yield and productivity of alcoholic fermentation has been evaluated. The methodology used was factorial design and response surface analysis. Within the range studied only for phosphorus a statistically significant effect was observed. The broth of sugar cane of the CB 453 variety already possessed enough nitrogen for the fermentation. The mathematical and empirical model was validated for productivity and not for yield. The concentration of alcohol produced in the fermentation was not enough to cause cellular growth inhibition.
  • Chemical constituents of the fruits of Copaifera langsdorffii Desf. Artigo

    Lima Neto, José de Sousa; Gramosa, Nilce Viana; Silveira, Edilberto Rocha

    Abstract in English:

    Phytochemical investigation of the hexane extract of fruit shells of Copaifera langsdorffii Desf. (Caesalpinioideae) afforded ent-kaur-16-en-19-oic acid, polyalthic acid, nivenolide and the mixture of caryophyllene oxide and ent-kaur-16-en-19-oic acid. The chloroform extract of unripe seeds led to the isolation of coumarin and the GC/MS analysis of the extract allowed the identification of 81.8% of the fatty acid composition after hydrolysis followed by methylation. The main fatty acid identified was oleic acid (33.1%). The isolation of all secondary metabolites was accomplished by modern chromatographic methods and the structure determination was accomplished by spectrometric methods (IR, MS, NMR ¹H and 13C).
  • Composition and antibacterial activity of the essential oils of Senecio crassiflorus var. crassiflorus Artigo

    Murari, Anelise Levay; Carvalho, Fernanda Hernandes de; Heinzmann, Berta Maria; Michelot, Tiago Mozzaquatro; Hörner, Rosmari; Mallmann, Carlos Augusto

    Abstract in English:

    The essential oils of leaves, aerial and underground stems of Senecio crassiflorus var. crassiflorus were extracted by hydrodistillation and their analyses were performed by GC/MS. Qualitative and quantitative differences have been found between the analyzed parts. The main compounds of the essentials oils of the leaves were found to be oxygenated sesquiterpenes, while the oils from the aerial and underground stems showed sesquiterpene hydrocarbons as major constituents. Furthermore, the essential oils were tested against Staphylocccus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus. The essential oil of the leaves was shown to be the most active.
  • Characterization of O-acetil-(4-O-methylglucurono)xylans from Eucalyptus urograndis Artigo

    Magaton, Andréia da Silva; Piló-Veloso, Dorila; Colodette, Jorge Luiz

    Abstract in English:

    The O-acetyl-4-O-methyl-(glucurono)xylans were isolated from E. urograndis by extraction with dimethyl sulfoxide, analysed for monosaccharide composition and structurally characterized by NMR spectroscopy. These xylans contained one 4-O-methyl-glucuronic acid substituent and 5.5 acetyl groups for approximately 10 xylose residues. About 10% of 4-O-methyl-glucuronic acid (MeGlcA) units were branched at O-2. The O-acetyl-4-O-methyl-(glucurono)-xylans were composed of the following (1 → 4)-linked β-D-xylopyranosyl structural elements: unsubstituted (51 mol%), 2-O-acetylated (12 mol%), 3-O-acetylated (20 mol%), 2,3-di-O-acetylated (6 mol%) and [MeGlcA α-(1 → 2)] [3-O-acetylated] (11 mol%). The weight-average molar mass and polydispersity of this xylan were 34.9 kDa and 1.16, respectively, as measured by size-exclusion chromatography.
  • Assessment of fate and bioaccumulation of benzo(a)pirene by computer modeling Artigo

    Froehner, Sandro; Martins, Raquel Fernandes

    Abstract in English:

    The objective of this work was to evaluate the environmental distribution of benzo(a)pirene, a polycyclic aromatic hydrocarbon, by the EQC model. The modeling of the contaminant distribution was accomplished by means of the fugacity model applied to a hypothetical scenario constituted by air, water, soil and sediment. The modeling and simulations revealed that the soil is the preferential compartment. We also discuss the implications of the results about fate and ecological risks associated with benzo(a)pirene. We concluded that the emissions of HPAs can not be ignored and bioaccumulation among others risks can be induced.
  • Determination of palladium in biological samples applying nuclear analytical techniques Artigo

    Cavalcante, Cássio Q.; Sato, Ivone M.; Salvador, Vera L. R.; Saiki, Mitiko

    Abstract in English:

    This study presents Pd determinations in bovine tissue samples containing palladium prepared in the laboratory, and CCQM-P63 automotive catalyst materials of the Proficiency Test, using instrumental thermal and epithermal neutron activation analysis and energy dispersive X-ray fluorescence techniques. Solvent extraction and solid phase extraction procedures were also applied to separate Pd from interfering elements before the irradiation in the nuclear reactor. The results obtained by different techniques were compared against each other to examine sensitivity, precision and accuracy.
  • A multi-screening approach for marine-derived fungal metabolites and the isolation of cyclodepsipeptides from Beauveria felina

    Vita-Marques, Aline Maria de; Lira, Simone P.; Berlinck, Roberto G. S.; Seleghim, Mirna H. R.; Sponchiado, Sandra R. P.; Tauk-Tornisielo, Sâmia M.; Barata, Margarida; Pessoa, Claudia; Moraes, Manoel O. de; Cavalcanti, Bruno Coêlho; Nascimento, Gislene G. F.; Souza, Ana O. de; Galetti, Fabio C. S.; Silva, Célio L.; Silva, Marcio; Pimenta, Eli F.; Thiemann, Otavio; Passarini, Michel R. Z.; Sette, Lara D.

    Abstract in English:

    Extracts obtained from 57 marine-derived fungal strains were analyzed by HPLC-PDA, TLC and ¹H NMR. The analyses showed that the growth conditions affected the chemical profile of crude extracts. Furthermore, the majority of fungal strains which produced either bioactive of chemically distinctive crude extracts have been isolated from sediments or marine algae. The chemical investigation of the antimycobacterial and cytotoxic crude extract obtained from two strains of the fungus Beauveria felina have yielded cyclodepsipeptides related to destruxins. The present approach constitutes a valuable tool for the selection of fungal strains that produce chemically interesting or biologically active secondary metabolites.
  • Ethanol production from castor bean cake (Ricinus communis L.) and evaluation of the lethality of the cake for mice Artigo

    Melo, Walber Carvalho; Silva, Daniele Barreto da; Pereira Jr., Nei; Anna, Lídia Maria Melo Santa; Santos, Alexandre Soares dos

    Abstract in English:

    The castor bean cake is rich in starch (48 ± 0.53%) and bears a problem linked to the occurrence of a toxic protein (ricin). The chemical hydrolysis (ratio solid:liquid = 1:6; H2SO4= 0.1 mol L-1; 120 °C; 40 min) generated a medium with 27 g L-1 of reducing sugars (hydrolysis efficiency= 32%). The hydrolyzed product was fermented and produced 11 g L-1 of ethanol (volumetric productivity=1.38 g L-1 h-1 and ethanol yield on substrate consumed=0.45 g g-1). In vivo experiments (DL50) revealed a reduction of roughly 240 times in the CBC toxicity (2.11 µg g-1).
  • Study of metal and trace element mobilization in aquatic environments of Brazilian semi-arid zones applying principal component analysis Artigo

    Santos, José Soares dos; Santos, Maria Lúcia Pires dos; Oliveira, Elisabeth de

    Abstract in English:

    The spatial and temporal retention of metals has been studied in water and sediments of the Gavião River, Anagé and Tremedal Reservoirs, located in the semi-arid region, Bahia - Brazil, in order to identify trends in the fluxes of metals from the sediments to the water column. The determination of metals was made by ICP OES and ET AAS. The application of statistical methods showed that this aquatic system presents suitable conditions to move Cd2+ and Pb2+ from the water column to the sediment.
  • Spectrophotometric determination of sildenafil citrate in pharmaceutical formulations Artigo

    Weinert, Patrícia Los; Pezza, Leonardo; Pezza, Helena Redigolo

    Abstract in English:

    This paper describes a simple and rapid spectrophotometric method for quantitative determination of sildenafil citrate based on its reaction with p-chloranil accelerated by hydrogen peroxide, producing a stable purple compound (λmax= 535 nm). In the absence of peroxide this reaction is very slow. The experimental conditions were optimized by using response surface methodologies. Beer's law is obeyed in a concentration range of 8.52 x 10-5 - 1.70 x 10-3 mol L-1 (r = 0.999). The detection limit was 1.96 x 10-5 mol L-1. The method was successfully applied for the determination of sildenafil citrate in medicines with good accuracy and precision.
  • Chemical analysis of red pigment in human bone Artigo

    Cavalcante, Luis Carlos Duarte; Lage, Maria Conceição Soares Meneses; Fabris, José Domingos

    Abstract in English:

    This work presents a chemical study of human bones painted red located at the Morro dos Ossos site, Piauí State, Brazil. The pigment was studied using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), complexation reactions with thiocyanate and UV-Vis absorption spectroscopy. The results confirmed the presence of ochre and that the pigment layer is essentially composed of a mixture of clay and hematite, α-Fe2O3.
  • Simultaneous spectrophotometric determination of ezetimibe and simvastatin in pharmaceutical preparations using chemometric techniques

    Palabiyik, Ismail Murat; Onur, Feyyaz; Yardimci, Ceren; Özaltin, Nuran

    Abstract in English:

    Two spectrophotometric methods are described for the simultaneous determination of ezetimibe (EZE) and simvastatin (SIM) in pharmaceutical preparations. The obtained data was evaluated by using two different chemometric techniques, Principal Component Regression (PCR) and Partial Least-Squares (PLS-1). In these techniques, the concentration data matrix was prepared by using the mixtures containing these drugs in methanol. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances in the range of 240 - 300 nm in the intervals with Δλ = 1 nm at 61 wavelengths in their zero order spectra, then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of EZE and SIM in their mixture. The procedure did not require any separation step. The linear range was found to be 5 - 20 µg mL-1 for EZE and SIM in both methods. The accuracy and precision of the methods were assessed. These methods were successfully applied to a pharmaceutical preparation, tablet; and the results were compared with each other.
  • Phytochemical study of Gypsophila trichotoma wend. (Caryophyllaceae)

    Krasteva, Ilina N.; Popov, Ivo S.; Balabanova, Vessela I.; Nikolov, Stefan D.; Pencheva, Ivanka P.

    Abstract in English:

    Phytochemical studies of ethyl acetate extracts from the roots and aerial parts of Gypsophila trichotoma revealed the presence of stigmast-7-en-3-ol, stigmasta-7,22-dien-3-ol (spinasterol), ergost-7-en-3-ol, stigmasta-3,5dien7-one, β-sitosterol, 22,23-dihydrospinasterone, vitexin, orientin, homoorientin and hyperoside. The structures of the compounds were determined by GC/MS and HPLC analyses.
  • Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

    Andrade, Renato Pereira de; Santana Filho, Salomão; Mello, Jaime Wilson Vargas de; Figueiredo, Bernardino Ribeiro de; Dussin, Tânia Mara

    Abstract in English:

    Acid drainage results from exposition of sulfides to the atmosphere. Arsenopyrite is a sulfide that releases arsenic (As) to the environment when oxidized. This work evaluated the As mobility in six sulfidic geomaterials from gold mining areas in Minas Gerais State, Brazil. Grained samples (<2 mm) were periodically leached with distilled water, during 70 days. Results suggested As sorption onto (hydr)oxides formed by oxidation of arsenopyrite. Low pH accelerated the acid generation, dissolving Fe oxihydroxides and releasing As. Presence of carbonates decreased oxidation rates and As release. On the other hand, lime added to a partially oxidized sample increased As mobilization.
  • Development and physicochemical characterization of dexamethasone-loaded polymeric nanocapsule suspensions

    Friedrich, Rossana Barcellos; Fontana, Marcia Camponogara; Beck, Ruy Carlos R.; Pohlmann, Adriana Raffin; Guterres, Silvia Stanisçuaski

    Abstract in English:

    The influence of drug concentration, oil phase, and surfactants on the characteristics of dexamethasone-loaded nanocapsules was investigated. The best formulations were obtained at dexamethasone concentrations of 0.25 and 0.50 mg.mL-1 (encapsulation efficiency: 80-90%; mean size: 189-253 nm). The type of oil phase influenced only the stability of dexamethasone-loaded nanocapsules. The association of polysorbate 80 and sorbitan monooleate provided a more stable formulation. Sunflower oil and sorbitan sesquioleate used for the first time as oil phase and surfactant for nanocapsules, respectively, have allowed obtaining suspensions with low mean size and narrow size distribution.
  • Simulataneous determination of tartaric, malic, ascorbic and citric acids in acerola, açai and cashew pulps, and stability evaluation in cashew juices Artigo

    Scherer, Rodrigo; Rybka, Ana Cecília Poloni; Godoy, Helena Teixeira

    Abstract in English:

    The aim of the present study was determining the main organic acids in pulp and juices, as well as evaluating their stability, after opening the package, by liquid chromatography in a C18 column with isocratic elution and UV detection. In açaí pulp tartaric, malic and citric acids were found. Cashew samples presented all of the organic acids evaluated, besides high concentrations of ascorbic and malic acids. Acerola pulp had the highest ascorbic acid concentration. A small decrease in organic acid content during storage was observed. Malic and citric acids seem to be more stable than tartaric and ascorbic acids.
  • Periodic table of the elements in the perspective of artificial neural networks Artigo

    Lemes, Maurício Ruv; Pino Júnior, Arnaldo Dal

    Abstract in English:

    Although several chemical elements were not known by end of the 18th century, Mendeleyev came up with an astonishing achievement: the periodic table of elements. He was not only able to predict the existence of (then) new elements but also to provide accurate estimates of their chemical and physical properties. This is certainly a relevant example of the human intelligence. Here, we intend to shed some light on the following question: Can an artificial intelligence system yield a classification of the elements that resembles, in some sense, the periodic table? To achieve our goal, we have fed a self-organized map (SOM) with information available at Mendeleyev's time. Our results show that similar elements tend to form individual clusters. Thus, SOM generates clusters of halogens, alkaline metals and transition metals that show a similarity with the periodic table of elements.
  • Immobilization of iron (II) in alginate matrix and its use in textile dye degradation by Fenton processes Artigo

    Souza, Kely Viviane de; Peralta-Zamora, Patricio; Zawadzki, Sônia Faria

    Abstract in English:

    In this work Fenton and photo-Fenton processes for textile dye degradation were investigated using iron (II) immobilized in alginate spheres. Photomicrographs obtained by scanning electron microscopy showed an irregular and porous surface with a homogeneous distribution of iron. The Fenton process was used to evaluate the degradation efficiency of reactive dyes and this procedure showed a low degradation effect. The association of artificial visible light or solar radiation in the Fenton process (foto-Fenton process) showed degradation ratios of 70 and 80% respectively in 45 min. It was also observed that the iron-alginate matrix can be reused.
  • Study of electrocrystallization of Ni and Ni-P on platinum ultramicroelectrode Artigo

    Eguiluz, Katlin Ivon Barrios; Avaca, Luis Alberto; Barin, Cláudia Smaniotto

    Abstract in English:

    This work describes a comparative study of the electrocrystallization of Ni and Ni-P on Pt ultramicroelectrodes using chronoamperometric measurements. It was possible to confirm that in all cases a progressive nucleation was the predominant mechanism. Moreover, the application of the Atomistic Theory to the experimental rate of nuclei formation showed that the number of atoms in the critical nucleus was zero, except for Ni-P on Pt at low overpotentials were a value of one was observed. Furthermore, the physical characterisation of the different deposits on Pt by atomic force microscopy allowed observing the coalescence of the hemispherical nuclei of Ni and Ni-P at t max thus confirming the results obtained from the current-time analysis.
  • Adsorption applied to the removal of ammonia from pre-treated piggery wastewater Artigo

    Higarashi, Martha Mayumi; Kunz, Airton; Mattei, Rosemari Martini

    Abstract in English:

    The aim of this work is to evaluate the use of natural zeolites to remove the NH4+ that remains in effluents from swine facilities which were submitted to physico-chemical and biological treatments. Experiments were made in batch made adding 5% (w/w) of adsorbent (0.6-1.3 and 3.0-8.0 mm) to synthetic and real swine facilities effluents. The results show that ammonium removal is influenced by adsorbent particle size and the presence of other ions in the effluent. The adsorption equilibrium was described by Langmuir as well as Freundlich isotherms and the kinetic data fitted well a pseudo-second order model.
  • Synthesis, structure and physicochemical properties of zinc and copper complexes based on sulfonamides containing 8-aminoquinoline ligands

    Silva, Luiz Everson da; Sousa Jr., Paulo Teixeira de; Joussef, Antonio Carlos; Piovezan, Clóvis; Neves, Ademir

    Abstract in English:

    Sulfonamides obtained by reaction of 8-aminoquinoline with 4-nitrobenzenesulfonylchloride and 2,4,6-triisopropylbenzenesulfonyl chloride were used to synthesize coordination compounds with CuII and ZnII with a ML2 composition. Determination of the crystal structures of the resulting zinc and copper complexes by X-ray diffraction show a distorted tetrahedral environment for the [Cu(qnbsa)2], [Cu(qibsa)2] and [Zn(qibsa)2] complexes in which the sulfonamide group acts as a bidentate ligand through the nitrogen atoms from the sulfonamidate and quinoline groups. The complex [Zn(qnbsa)2] crystallizes with a water molecule from the solvent and the Zn is five-coordinated and shows a bipyramidal-trigonal geometry. The electrochemical and electronic spectroscopy properties of the copper complexes are also discussed.
  • Characterization of activated bauxite before and after saturation with insulating mineral oil Artigo

    Piluski, Josélia Ednar Antunes; Hotza, Dachamir

    Abstract in English:

    A characterization of activated bauxite and of activated bauxite impregnated with insulating mineral oil was made. The activated bauxite is used as adsorbent material in percolators during the regeneration of insulating mineral oil. After regeneration an insulating mineral oil is obtained with physical and chemical characteristics similar to those of the new oil. Moreover, saturated activated bauxite impregnated with insulating mineral oil is also produced. It is a dangerous residue according to NBR 10004 (Class I) and, thus, harmful to the environment. An alternative use of this waste in the ceramic industry is discussed.
  • Glutathione and related enzymes: biological roles and importance in pathological processes Revisão

    Huber, Paula C.; Almeida, Wanda P.; Fátima, Ângelo de

    Abstract in English:

    Glutathione (GSH) and related enzymes are pivotal for the normal functioning of several important biological processes. In this review we discuss the biosynthesis and the catalytic cycles of glutathione as well as the major GSH-related enzymes. We also present how glutathione and enzymes are involved in cancer and the chromatographic and non-chromatographic methods used to analyze glutathione and/or its derivatives.
  • Sampling and analytical methods for atmospheric reduced sulphur compounds Revisão

    Cruz, Lícia P. S.; Campos, Vânia P.

    Abstract in English:

    This work presents a review of sampling and analytical methods that can be applied to atmospheric traces of reduced sulphur compounds (RSC) in the atmosphere. Sampling methodology involving discontinuous methods with preconcentration is mostly used. For the most part, adsorption on solids and cryogenic capture are applied as a procedure. The analysis of these compounds has been done mainly by gas chromatography with FPD, fluorescence and spectrophotometry. Advantages and disadvantages of the methodologies are also mentioned in this paper, aiming to guide the reader towards the most appropriate choice of a sampling and analytical method for RSCs.
  • Validation of chromatographic methods for the determination of residues of veterinary drugs in foods Revisão

    Paschoal, Jonas Augusto Rizzato; Rath, Susanne; Airoldi, Flavia Pereira da Silva; Reyes, Felix G. R.

    Abstract in English:

    Different agencies that supply validation guidelines worldwide establish almost the same parameters to be evaluated in the validation process of bioanalytical methods. However, they recommend different procedures, as well as establish different acceptance criteria. The present review delineates and discusses the stages involved in the validation procedures of bioanalytical methods designed for determining veterinary residues in food, explaining the main differences in the guidelines established for this purpose by the main regulatory agencies in the world.
  • Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts Revisão

    Santos, João H. Z. dos; Fisch, Adriano G.; Cardozo, Nilo S. M.; Secchi, Argimiro R.

    Abstract in English:

    The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest.
  • Supramolecular chemistry of pyrazolyl complexes Revisão

    Godoy Netto, Adelino Vieira de; Frem, Regina Célia Galvão; Mauro, Antonio Eduardo

    Abstract in English:

    The purpose of this review is to describe the progress in the supramolecular chemistry of the pyrazolyl-based metal complexes. The text is written under the structural point of view, emphasizing the role of the covalent and non-covalent interactions in the rational construction of super and supramolecules.
  • Analytical procedures for identifying anthocyanins in natural extracts Revisão

    Março, Paulo Henrique; Poppi, Ronei Jesus; Scarminio, Ieda Spacino

    Abstract in English:

    Anthocyanins are among the most important plant pigments. Due to their potential benefits for human health, there is considerable interest in these natural pigments. Nonetheless, there is great difficulty in finding a technique that could provide the identification of structurally similar compounds and estimate the number and concentration of the species present. A lot of techniques have been tried to find the best methodology to extract information from these systems. In this paper, a review of the most important procedures is given, from the extraction to the identification of anthocyanins in natural extracts.
  • Comparative study of screening techniques for antibacterial activity evaluation of plant crude extracts and pure compounds Nota Técnica

    Alves, Everton Giovanni; Vinholis, Adriana Helena Chicharo; Casemiro, Luciana Assirati; Furtado, Niege Araçari Jacometti Cardoso; Silva, Márcio Luis Andrade e; Cunha, Wilson Roberto; Martins, Carlos Henrique Gomes

    Abstract in English:

    In this work, the effectiveness of four screening techniques (three techniques of the diffusion method and one microdilution broth method) were compared. Evaluated were the ethanolic and dichloromethanic extracts of Miconia rubiginosa (Melastomataceae) against six standard bacteria (ATCC). The results showed statistical disagreement among the three diffusion techniques. Among the diffusion techniques, the well technique displayed the best result. However the microdilution broth method demonstrated to be the most adequate method to evaluate the antibacterial activity of plant crude extracts and pure compounds when compared to the other methodologies.
  • Liquid-liquid extraction (LLE) of Fe(III) and Ti(IV) by bis-(2-ethyl-hexyl) phosphoric acid (D2EHPA) in sulfuric acid medium Nota Técnica

    Silva, Glauco Corrêa da; Cunha, José Waldemar Silva Dias da; Dweck, Jo; Afonso, Julio Carlos

    Abstract in English:

    This work presents a study on the separation of Fe(III) and Ti(IV) from sulfuric acid leaching solutions of ilmenite (FeTiO3) using liquid-liquid extraction with D2EHPA in n-dodecane as extracting agent. The distribution coefficients (K D) of the elements related to free acidity and concentration of Fe(III) and Ti(IV) were determined. Free acidity was changed from 3x10-2 to 11.88 mol L-1 and D2EHPA concentration was fixed at 1.5 mol L-1. Recovery of final products as well as recycling of wastes generated in the process were also investigated. The LLE process as a feasible alternative to obtain high-purity TiO2.
  • Removal of ammonium ions from waters produced in petroleum offshore exploitation by adsorption on clinoptilolite Nota Técnica

    Lima, Rosilda Maria Gomes de; Wildhagen, Glória Regina da Silva; Cunha, José Waldemar Silva Dias da; Afonso, Julio Carlos

    Abstract in English:

    This work describes the use of clinoptilolite for removal of ammonium ions present in waters produced at the Campos' Basin. Samples were previously treated in order to remove organic compounds and metals. Experiments were run in fixed- and fluidized-bed systems, at room temperature. The fluidized-bed systems did not remove efficiently the ammonium ion. The best operational conditions were obtained with clinoptilolite particle size in the range 0.30-0.50 mm, under ascendant flow (3 mL min-1), in a fixed-bed system. The best zeolite performance was found when it was pretreated with 0.5 mol L-1 NaOH. Na+ was the most important interfering ion due to its high concentration in the water. Clinoptilolite lost partially its capacity to retain ammonium ions after several regeneration cycles with NaOH.
  • Teaching organic reactions using computational chemistry: I. eletrophilic addition reactions to alkenes Educação

    Mariano, Arquimedes; Ventura, Elizete; Monte, Silmar A. do; Braga, Claudia F.; Carvalho, Antônio B.; Araújo, Regiane C. M. U.; Santana, Otávio L.

    Abstract in English:

    Basic concepts that play an important role in some organic reactions are revisited in this paper, which reports a pedagogical experience involving undergraduate and graduate students. A systematic procedure has been applied in order to use widespread available computational tools. This paper aims to discuss the use of computers in teaching electrophilic addition reactions to alkenes. Two classical examples have been investigated: addition to non-conjugated alkenes and addition to conjugated dienes. The results were compared with those normally discussed in organic textbooks. Several important concepts, such as conformational analysis and energy control (kinetic and thermodynamic) involved in reaction mechanisms can be taught more efficiently if one connects theoretical and practical tools.
  • Building knowledge through work projects: an experiment in the chemistry course of the state university os Santa Cruz in Bahia Educação

    Wartha, Edson José; Guzzi Filho, Neurivaldo José; Jesus, Raildo Mota de

    Abstract in English:

    In this work, we describe a pedagogical experiment using work projects in chemistry undergraduate programs in general chemistry and inorganic chemistry courses making learning more dynamic and consolidating the link between students and the external community. We highlight as fundamental outcomes the improvement in the learning process and, above all, the active participation of the students in investigation and problem-solving activities.
  • Characterization of the intrinsic reactivity of halobenzenes in the framework of conceptual DFT

    Moncada, José Luis; Morán, Guillermo Salgado

    Abstract in English:

    The aim of this paper is to study the family of halobenzenes for characterizing their intrinsic reactivity and in this way to establish a rational order of the intrinsic reactivity of this family of molecules in the electrophilic aromatic substitution. This study was carried out in the framework of Density Functional Theory which provides a global and local index that can be used in the characterization of the reactivity. This index is related to some concept derivatives of experimental chemistry, being a good approach to the characterization of halobenzenes.
  • Extraction of β-carotene from carrots: a proposal for experimetal courses in chemistry Educação

    Zeraik, Maria Luiza; Yariwake, Janete Harumi

    Abstract in English:

    This paper reports on the development of a simple and fast procedure for β-carotene extraction from carrots and its quantification by UV/Vis spectroscopy. Carotenoids extracted from carrots may also be used as alternative reagents for TLC (thin layer chromatography) detection of natural compounds with antioxidant properties, replacing the commercial p.a. grade β-carotene. Although this reagent had around 10% b-carotene, it proved to be as efficient for TLC analysis as the commercial p.a. grade β-carotene. This practice is a useful alternative for teaching undergraduate organic chemistry laboratory classes.
  • Considerations about the role of scientific communication in chemistry education Educação

    Oliveira, Jane Raquel Silva de; Queiroz, Salete Linhares

    Abstract in English:

    In the present work, we provide some considerations about the role of scientific communication in Chemistry Education. Such considerations may subsidize the development of communication in scientific language by Chemistry students. These considerations are based on information collected during a participatory research for the production of didactic material about scientific communication. The meetings were audio recorded and the contents of the participants' speeches were divided into categories. The category analysis supported the elaboration of the considerations.
  • Malaria: historical aspects and chemoterapy Assuntos Gerais

    França, Tanos C. C.; Santos, Marta G. dos; Figueroa-Villar, José D.

    Abstract in English:

    Malaria is still a very serious worldwide public health problem affecting between 300 and 500 million people and causing from 1.0 to 2.5 million deaths annually. The major problems with this disease are the lack of efficient vaccines and the rapid emergence of chemotherapy resistant P. falciparum strains. In this work we present a synopsis and discussion on malaria to provide the readers with some information on the historical aspects and relevance of this disease as well as the chemotherapy in use today.
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