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Química Nova, Volume: 32, Número: 4, Publicado: 2009
  • 32ªReunião Anual da SBQ Editorial

    Catalani, Luiz Henrique
  • Estudo de metais e de substâncias tóxicas em brinquedos Artigo

    Zini, Josiane; Ferreira, João C.; Carvalho, Fátima M. S. de; Bustillos, José O. W.V.; Scapin, Marcos A.; Salvador, Vera L. R; Abrão, Alcídio

    Resumo em Inglês:

    The main goal of the present study is the analysis of toxic elements in plastic toys commercialized in Brazil. Metals like cadmium, lead, chromium, zinc, and aluminum, along with organic substances, such as phthalates, were identified in different toys by quantitative analytical techniques. Traces of thorium were detected in one of the studied samples. Although the measured radioactive dose was rather low, the presence of such a radioactive contaminant is against to the International Agency of Atomic Energy regulations. Similar toys manufactured in Brazil were analyzed and found to observe the standards defined by the National Institute of Metrology (Inmetro).
  • Avaliação de metais traços e íons majoritários em águas de chuva na cidade de São Paulo Artigo

    Fontenele, Anna Paula Godoy; Pedrotti, Jairo J.; Fornaro, Adalgiza

    Resumo em Inglês:

    Rainfall samples collected in the downtown area of São Paulo city, during 2003, exhibited average concentrations of cadmium, lead and copper of 1.33, 8.52 and 49.5 nmol L-1, respectively. Among the major ions, NH4+ was the predominant species followed by NO3-, SO4(2-) and Ca2+, with volume weighed mean (VWM) concentrations of 37.1, 20.1, 11.9 and 10.8 µmol L-1, respectively. All the determined species showed high inter-events variability, including free H+ ions whose VWM concentration was 4.03 µmol L-1, corresponding to a pH value of 5.39.
  • Efeito de substâncias empregadas para remoção de cobre sobre o teor de compostos secundários da cachaça Artigo

    Lima, Annete de J. Boari; Cardoso, Maria das Graças; Guimarães, Luiz Gustavo de L.; Lima, José Maria de; Nelson, David Lee

    Resumo em Inglês:

    High copper content is of great concern among producers of sugar-cane spirits who frequently use filters instead of cleaning the stills. This study compared the efficiency of activated carbon, ion-exchange-polymeric resin, and activated-carbon/iron-oxide magnetic composite for copper reduction without removing excessive organic compounds that are important for the beverage's quality. Resin was the most efficient copper adsorbent, removing fewer organic compounds. The composite also removed copper; however, it also removed large amounts of organic compounds. Activated carbon didn't remove sufficient copper to reduce its concentration to less than 5 g L-1, and it removed large amounts of higher alcohols and esters.
  • Métodos de extração e qualidade da fração lipídica de matérias-primas de origem vegetal e animal Artigo

    Brum, Aelson Aloir Santana; Arruda, Lia Ferraz de; Regitano-d´Arce, Marisa Aparecida Bismara

    Resumo em Inglês:

    Methodologies of extraction of lipids from chicken breast and oats flakes were evaluated: Soxhlet, Folch et al., Bligh & Dyer and Hara & Radin. For chicken breast, the methods Soxhlet, Folch et al. and Bligh & Dyer presented the highest yields in total lipids. With oat flakes, the methods Soxhlet and Bligh & Dyer presented higher yields than the Hara & Radin and Folch et al. The Soxhlet method affected the quality of the lipid fraction in both samples. Extracted lipid components were separated by thin layer chromatography, the chloroform-methanol based was more efficient to extract the neutral and polar lipids.
  • Validation of an analytical methodology for the quantitative analysis of petroleum hydrocarbons in marine sediment samples

    Damas, Eloy Yordad Companioni; Medina, Miriam Odette Cora; Clemente, Ana Catalina Núñez; Díaz, Miguel Ángel Díaz; Bravo, Luis González; Ramada, Rolando Marbot; Porto, Rodny Montes de Oca

    Resumo em Inglês:

    This work describes a validation of an analytical procedure for the analysis of petroleum hydrocarbons in marine sediment samples. The proposed protocol is able to measure n-alkanes and polycyclic aromatic hydrocarbons (PAH) in samples at concentrations as low as 30 ng/g, with a precision better than 15% for most of analytes. The extraction efficiency of fortified sediments varied from 65.1 to 105.6% and 59.7 to 97.8%, for n-alkanes and PAH in the ranges: C16 - C32 and fluoranthene - benzo(a)pyrene, respectively. The analytical protocol was applied to determine petroleum hydrocarbons in sediments collected from a marine coastal zone.
  • Variabilidade sazonal e biossíntese de terpenóides presentes no óleo essencial de Lippia alba (Mill.) N. E. Brown (Verbenaceae) Artigo

    Barros, Francisco Maikon Corrêa de; Zambarda, Eduardo de Oliveira; Heinzmann, Berta Maria; Mallmann, Carlos Augusto

    Resumo em Inglês:

    The essential oil of the leaves of Lippia alba chemotype linalool-1,8-cineol was extracted by hidrodistillation at different seasons and analyzed by GC/MS. Qualitative and quantitative variations in regard to the period of harvesting have been performed and the results were correlated with meteorological data. The essential oil yield varied from 0.33 to 0.67%. The chemical diversity of the constituents increased throughout the year, being 1,8-cineol and linalool the major components. Possible biosynthetic routes of mono and sesquiterpenoids present in the essential oil are discussed.
  • Caracterização de subproduto da indústria de alumínio e seu uso na retenção de cádmio e chumbo em sistemas monoelementares Artigo

    Costa, Enio Tarso de Souza; Guilherme, Luiz Roberto Guimarães; Curi, Nilton; Lopes, Guilherme; Visioli, Elton Luiz; Oliveira, Luiz Carlos Alves de

    Resumo em Inglês:

    The present work aimed to characterize an aluminum industry by-product in natura (L.A. nat) and after phosphate and thermal pretreatments; evaluate the adsorption/desorption capacity of Cd and Pb by this L.A. nat form and after the aforementioned pretreatments, comparing them with an in natura iron mining by-product (L.F. nat). The L.A. nat presented a high pH as well as a high Na concentration and also an oxide-rich mineralogy. Pretreatment of the by-product had no significant effect upon Cd and Pd adsorption/desorption. The L.A. nat performed better than the L.F. nat as an Cd and Pb adsorbent.
  • Desenvolvimento e validação de metodologia analítica por CLAE-IR para determinação de artemisinina em Artemisia annua L Artigo

    Celeghini, Renata Maria dos Santos; Sousa, Ilza Maria de Oliveira; Silva, Ana Paula da; Rodrigues, Rodney Alexandre Ferreira; Foglio, Mary Ann

    Resumo em Inglês:

    The aim of this work was to develop and validate an analytical methodology for determination of artemisinin used as antimalaric. The method was based on high performace liquid chromatography, using a CN column with mobile phase composed of methanol : H2O 50:50 (V/V). The results showed that the method presented linearity from 50 to 1500 µg/mL. It was considered selective, accurate, precise according to the specific resolution from ANVISA, the Brazilian regulatory agency.
  • Aplicação de zeólitas sintéticas como coadjuvante em formulação detergente Artigo

    Sutili, Felipe K.; Miotto, Naiara; Rigoti, Eduardo; Pergher, Sibele B. C.; Penha, Fábio G.

    Resumo em Inglês:

    The study consists is the application of zeolites NaX, NaY and A as builder in detergent formulations to eliminate the hardness of water. Therefore, the adsorption of ions Ca+2 and Mg+2 were evaluated, and the effect of the cleaning action of the surfactant sodium dodecil sulfate (SDS) through tests of detergency. The experiments were conducted in bath system (with shaking) and quantification of metals was performed by atomic absorption spectrometry. Zeolite A showed the best results for adsorption of Ca++ and Mg++ with retention rates of around 90 and 70% respectively and acted positively on the action of cleaning the surfactant SDS.
  • Estudo comparativo de métodos de preparo de amostras de tinta para a determinação de metais e metalóides por técnicas de espectrometria atômica Artigo

    Bentlin, Fabrina R. S.; Pozebon, Dirce; Depoi, Fernanda dos Santos

    Resumo em Inglês:

    This work deals with paint decomposition methods for major, minor and trace elements determination. Three methods were investigated: (1) decomposition in closed quartz vessel and heating in microwave oven; (2) decomposition in open vessel using HNO3 and ashing, following the ASTM D 3335-85a method; and (3) decomposition in open vessel using HNO3 + HF and ashing. Paints of different types and colours were analyzed, in which several elements were determined using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). It was observed that method (1) is appropriate for trace, minor and major elements determination, while method (3) is appropriate for Ti.
  • Propriedades redox da matéria orgânica isolada de material ultrafiltrado das águas do rio Paraíba do Sul Artigo

    Baldotto, Marihus Altoé; Canellas, Luciano Pasqualoto; Velloso, Ary Carlos Xavier; Rosa, Raul Castro Carriello; Maciel, Marcelo dos Santos; Rezende, Carlos Eduardo; Canela, Maria Cristina

    Resumo em Inglês:

    Previous studies indicated that free radicals control organic matter redox activities. In the present study, organic matter of an ultra-filtrated material collected from seven samples taken seasonally from the Paraiba do Sul River for two years were titrated with an oxidizer (I2) in an inert atmosphere. Standard formal potential values for the electrode MO Ox, MO Red ranged from 0.754 to 0.786 V at a 25 ºC temperature. Organic matter oxidation capacity (COx) per carbon mass varied according to pH values, and changes in COx were related to rainfall and river flow intensities.
  • Estudos químicos e biológicos de Microgramma vacciniifolia (Langsd. & Fisch.) Copel (Polypodiaceae) Artigo

    Peres, Marize T. L. P.; Simionatto, Euclésio; Hess, Sônia C.; Bonani, Vanderléa F. L.; Candido, Ana C. S.; Castelli, Caroline; Poppi, Nilva R.; Honda, Neli K.; Cardoso, Cláudia A. L.; Faccenda, Odival

    Resumo em Inglês:

    Chemical studies with aerial parts of Microgramma vacciniifolia (Langsd. & Fisch.) Copel. afforded ²-sitosterol, hopan-22-ol, 6-metoxiapinenin-7-O-²-D-allopyranoside and a mixture containing ethyl esters of carboxilic acids. The structures of the coumpounds were elucidated by spectroscopy and GC-MS analysis. The total phenolics contents of the crude extract and fractions were determined by Folin-Ciocalteau method. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH). The AcOEt fraction showed better activity in DPPH assay (9.9 ± 0.03 µg/mL), and presented also higher contents of the total phenolic (93.60 ± 1.11 µg/mg). Antimicrobial and allelopathic effects of the crude etanolic extract and fractions also were evaluated. In addition, the combination of biological activities was discussed.
  • Enriquecimiento, disponibilidad y contaminación de metales traza (Cd, Cu, Pb y Zn) en sedimentos de lagunas urbanas de Concepción-Chile

    González Sepúlveda, Elizabeth; Retamal Cifuentes, María; Medina Pedreros, Valentina; Ahumada Bermúdez, Ramón; Neira Hinojosa, José

    Resumo em Inglês:

    Trace metals (Cd, Cu, Pb and Zn) enrichment, availability and contamination in superficial sediments of three interconnected urban lagoons localized in Concepción-Chile, were evaluated. According to the results of geochemical fracctionation analysis, Cu and Pb are rather associated with oxi-hydroxides, Cd is associated with exchangeable and carbonates fraction, while Zn is mainly associated with organic, oxi-hydroxides and residual fraction. The estimation of the availability percentages indicate that Cu is the most mobile metal and the less mobile is the Cd. An evaluation of the geo-accumulation index and urban industrial pollution allowed to classify the studied zone as moderately to highly contaminated.
  • Double-bilayer: a new phase formed by lysophospholipids and the corresponding fatty acid

    Funari, Sérgio S.; Rapp, Gert; Richter, Frank

    Resumo em Inglês:

    The product of catalytic activity of the enzyme phospholipase A2, which resembles the core unit of animal toxins, on phospholipids is a 1:1 mixture of lysolipid and fatty acid. This mixture was studied by time-resolved simultaneous small- and wide angle x-ray diffraction over the temperature range from 23 to 53.5ºC. An unusually large lamellar structure was observed, with d = 11 nm, contradicting the complex functional dimer model between lysolipid and fatty acid. It can be explained by formation of a "double-bilayer", a new phase consisting of two different bilayers, one formed by lysophospholipid and other by fatty acid, bound together by head group interactions. Its strucutre was confirmed by simulations of the X-ray scattering pattern.
  • Desempenho físico-químico e mecânico de concreto de cimento Portland com borracha de estireno-butadieno reciclada de pneus Artigo

    Freitas, Camila; Galvão, José Carlos Alves; Portella, Kleber Franke; Joukoski, Alex; Gomes Filho, Carlos Vicente; Ferreira, Elizeu Santos

    Resumo em Inglês:

    Physicochemical and mechanical techniques were carried out to characterize three concrete tyre-rubber waste dosages such as 5, 10 and 15%, w/w. The elastomeric material was identified as styrene-butadiene rubber (SBR). It was observed that the growing SBR content in the mixture decreased the concrete performance. The best results were presented by 5% w/w tyre-rubber waste concrete sample. This composition was tested at Mourão hydroelectric powerplant spillway as repairing material.
  • Emprego de metodologia enzimática na obtenção de extratos protéicos de farinha de trigo Artigo

    Carreira, Raquel Linhares; Ramos, Camila Salles; Silva, Mauro Ramalho; Lopes Junior, Carlos de Oliveira; Silvestre, Marialice Pinto Coelho; Pirozi, Mônica Ribeiro

    Resumo em Inglês:

    An enzymatic method was used for obtaining protein extracts from wheat flour using an alkaline protease. Some parameters were evaluated aiming the optimization of this method: temperature (40-50 ºC); time (2-5 h); physical treatment of the sample (no treatment, ultra-turrax/16,000 rpm/5 min and ultrasound/120 W/10 min); enzyme:substrate ratio (E:S) of 5:100 - 10:100 and concentration of wheat flour (1:3, 1:5 and 1:10 w/v). The results showed that the best condition for protein extraction was that using the sample concentration of 1:3 (w/v), ultra-turrax, E:S of 10:100, at 40 ºC, 2 h, having reached an extraction yield of 88.53%.
  • Determinação de fósforo biodisponível em rações de peixes utilizando extração assistida por ultra-som e espectrofotometria no visível Artigo

    Moraes, Paula M. de; Loureiro, Vanessa R.; Padilha, Pedro M.; Neves, Renato de Cássio F.; Saleh, Mayra A. D.; Santos, Felipe A. dos; Silva, Fábio A.

    Resumo em Inglês:

    The aim of the present work was to develop and optimize a method for determination of bioavailable phosphorus in samples of feces and fish feed using ultrasound extraction and subsequent quantification by visible spectrophotometry. Using as extractor solution HNO3 0.50 mol L-1, the great conditions of extraction established were: sample mass - 100 mg, samples granulometry - < 60 µm, sonification time - five cycles of 40 s and ultrasound potency - 136 W. The proposed method was applied in studies of digestibility of this nutrient in different feeds used in diets of juvenile of Nile tilapia.
  • Aerosol particle size distributions at a traffic exposed site and an urban background location in Oporto, Portugal

    Oliveira, César; Alves, Célia; Pio, Casimiro A.

    Resumo em Inglês:

    Aerosol size distributions from 6 to 700 nm were measured simultaneously at an urban background site and a roadside station in Oporto. The particle number concentration was higher at the traffic exposed site, where up to 90% of the size spectrum was dominated by the nucleation mode. Larger aerosol mode diameters were observed in the urban background site possibly due to the coagulation processes or uptake of gases during transport. Factor analysis has shown that road traffic and the neighbour stationary sources localised upwind affect the urban area thought intra-regional pollutant transport.
  • Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado

    Paternina, Elihu; M. Arias, Juan; Barragán, Daniel

    Resumo em Inglês:

    The kinetic study of decomposition of hydrogen peroxide catalyzed by activated carbon was carried out. The effect of concentrations of reactants and temperature were experimentally studied. Kinetic data were evaluated using differential method of initial rates of reaction. When a typical kinetic law for reactions in homogeneous phase is used, first order of reaction is obtained for hydrogen peroxide and activated carbon, and activation energy of 27 kJ mol-1 for the reaction was estimated. Experimentally was observed that surface of activated carbon is chemically modified during decomposition of hydrogen peroxide, based on this result a scheme of reaction was proposed and evaluated. Experimental data fits very well to a Langmuir- Hinshelwood kinetic model and activation energy of 40 kJ mol-1 was estimated for reaction in heterogeneous phase.
  • Interesterificação química de óleo de soja e óleo de soja totalmente hidrogenado: influência do tempo de reação Artigo

    Ribeiro, Ana Paula Badan; Masuchi, Monise Helen; Grimaldi, Renato; Gonçalves, Lireny Aparecida Guaraldo

    Resumo em Inglês:

    Chemical interesterification is an important alternative to produce zero trans fats. In practice, however, excessive reaction times are used to ensure complete randomization. This work evaluated the influence of the reaction time on the interesterification of soybean oil/fully hydrogenated soybean oil blend, carried out in the following conditions: 100 ºC, 500 rpm stirring speed, 0.4% (w/w) sodium methoxide catalyst. The triacylglycerol composition, solid fat content and melting point analysis showed that the reaction was very fast, reaching the equilibrium within 5 min. This result suggests the interesterification can be performed in substantially lower times, with reduction in process costs.
  • Atividade antioxidante do extrato de sementes de limão (Citrus limon) adicionado ao óleo de soja em teste de estocagem acelerada Artigo

    Luzia, Débora Maria Moreno; Jorge, Neuza

    Resumo em Inglês:

    The aim of this work was to evaluate antioxidant activity of lemon seeds added to soybean oil, submitted to accelerated incubator-storage test and to determine its synergistic effect with the synthetic antioxidant TBHQ. The treatments Control, TBHQ (50 mg/kg), LSE (2,400 mg/kg Lemon Seed Extract), Mixture 1 (LSE + 50 mg/kg TBHQ) and Mixture 2 (LSE + 25 mg/kg TBHQ) were prepared and subjected to the accelerated incubator-storage test at 60 ºC for 12 days; samples were taken every 3 days and analyzed regarding peroxide value and conjugated dienes. The results showed that antioxidant activity of the tested treatments were: TBHQ = Mixture 1 = Mixture 2 > LSE > Control.
  • Biodegradação de fenol por uma nova linhagem de A spergillus sp. isolada de um solo contaminado do sul do Brasil Artigo

    Passos, Cátia Tavares dos; Burkert, Janaína Fernandes de Medeiros; Kalil, Susana Juliano; Burkert, Carlos André Veiga

    Resumo em Inglês:

    The main goal of this work was to study the biodegradation of phenol in batch mode by a filamentous fungus isolated from a contaminated site in Southern Brazil. A better performance was obtained by previous adaptation of the microorganism to the toxic chemical. A 2³ experimental design was proposed and it could be observed total phenol degradation in 72 h using 500 mg L-1 glucose, inoculum of 20% and agitation of 200 rpm, resulting a biodegradation rate of 3.76 mg L-1 h-1. In relation to phenol tolerance, Aspergillus sp. LEBM2 was able to consume up to 989 ± 15 mg L-1.
  • Remoção de azul de metileno de solução aquosa usando zeólitas sintetizadas com amostras de cinzas de carvão diferentes Artigo

    Fungaro, Denise Alves; Bruno, Mariza

    Resumo em Inglês:

    Batch sorption experiments were carried out to remove methylene blue from its aqueous solutions using zeolites synthesized from fly ashes as an adsorbent. The adsorbents were characterized by XFR, XRD and SEM. Nearly 90 min of contact time are found to be sufficient for the adsorption of dye to reach equilibrium. Equilibrium data have been analyzed using Langmuir and Freundlich isotherms and the results were found to be well represented by the Freundlich isotherm equation. Adsorption data were fitted to both Lagergren first-order and pseudo-second-order kinetic models and the data were found to follow pseudo-second-order kinetics.
  • Avaliação da contaminação do Igarapé do Sabino (Bacia do Rio Tibiri) por metais pesados, originados dos resíduos e efluentes do Aterro da Ribeira, em São Luís, Maranhão Artigo

    Campos, Antonio Eduardo Lopes; Nunes, Gilvanda Silva; Oliveira, José Crediciomar Silva de; Toscano, Ilda Antonieta Salata

    Resumo em Inglês:

    This work aimed to carry out an environmental monitoring in sabino narrow river (affluent of Tibiri Basin, in São Luís - MA, Brazil), in order to verify the main environmental impacts caused by effluent residues from Ribeira landfill. Chemical analysis and bibliographic and cartographic researches on this ecosystem were also carried out. In addition, heavy metals, such as Hg, Pb and Zn, were investigated in water samples by ICP-MS technique. It was observed that the contents of such heavy metals were above the tolerance limits established by the Brazilian legislation, showing a strong impact level on the evaluated ecosystem.
  • Determinação de 3,4-metilenodioximetanfetamina (MDMA) em comprimidos de Ecstasy por cromatografia líquida de alta eficiência com detecção por fluorescência (CLAE-DF) Artigo

    Costa, José Luiz da; Pintao, Estela Regina; Corrigliano, Célia Maria Castro; Negrini Neto, Osvaldo

    Resumo em Inglês:

    This paper describes the development and validation of simple and selective analytical method for determination of 3.4-methylenedioxymethamphetamine (MDMA) in Ecstasy tablets, using high performance liquid chromatography with fluorescence detection. Analysis was performed in a reversed phase column (LiChrospher 100 C18, 150 x 4.6 mm, 5 µm), isocratic elution with phosphate buffer 25 mmol/L pH 3.0 and acetonitrile (95:5, v/v). The method presents adequate linearity, selectivity, precision and accuracy. MDMA concentration in analyzed tablets showed a remarkable variability (from 8.5 to 59.5 mg/tablet) although the tablet weights were uniform, indicating poor manufacturing control thus imposing additional health risks to the users.
  • Estudo da especiação de arsênio inorgânico e determinação de arsênio total no monitoramento ambiental da qualidade de águas subterrâneas Artigo

    Borba, Ricardo Perobelli; Coscione, Aline Renée; Figueiredo, Bernardino Ribeiro; Zambello, Fábio

    Resumo em Inglês:

    This work reports an alternative, fast and robust method, for the determination of total As, As(III) and As(V) by HG-AAS without the use of prereductants. The method is based on the different rates of arsine formation of the inorganic As species and the effect of As(III) in the signal obtained for total As. Groundwater and mineral spiked waters were used to sample preservation evaluation. The method was validated by the determination of As in SRM 1640 and used in the determination of total As and its inorganic species in groundwater samples collected from mines in the Iron Quadrangle - MG.
  • Influência das características das substâncias húmicas aquáticas na eficiência da coagulação com o cloreto férrico Artigo

    Sloboda, Eliane; Vieira, Eny Maria; Dantas, Angela Di Bernardo; Di Bernardo, Luiz

    Resumo em Inglês:

    The aim of this study was to verify the influence of the apparent molecular size of aquatic humic substances on the effectiveness of coagulation with ferric chloride. Coagulation-filtration tests using jar test and bench-scale sand filters were carried out on samples of water with true color of approximately 100 Hazen units, prepared with aquatic humic substances of different molecular sizes (F1: < 0.45 µm, F2: 100 kDa - 0.45 µm, F3: 30 - 100 kDa and F4': < 30 kDa). For the water samples with lower apparent molecular size fractions, greater dosages of coagulant was needed to remove the color around 5.0 Hanzen units, mainly because these water samples contain higher concentrations of fulvic acids, which exhibited a larger number of negatively-charged groups.
  • Salicilatos isolados de folhas e talos de Salix martiana Leyb. (Salicaceae) Artigo

    Fernandes, Carromberth Carioca; Cursino, Lorena Mayara de Carvalho; Novaes, Jussival de Abreu Pinheiro; Demetrio, Camilla Avelino; Pereira Júnior, Orlando Libório; Nunez, Cecília Verônica; Amaral, Iêda Leão do

    Resumo em Inglês:

    Salix martiana Leyb. is an endemic species from the Amazon river floodplain areas (varzeas), of the State of Amazonas. Stems and leaves were extracted with dichloromethane, methanol and hydro-alcohol and these extracts were fractionated by using conventional chromatographic techniques. The major substances isolated, salicin and trichocarposide (6-0-p-coumaroyl salicin), were determined through analyses of NMR 1D (¹H and 13C) and NMR 2D (gHSQC and gHMBC). These compounds were isolated for the first time in Salix martiana Leyb. (Salicaceae). The percentage of these compounds in S. martiana is very high. The extracts were analyzed for their DPPH antioxidant capacity and the methanolic from the leaves and the hydro-alcoholic from the stems were the more active.
  • Efeito de matriz na quantificação de agrotóxicos por cromatografia gasosa Revisão

    Pinho, Gevany P.; Neves, Antônio A.; Queiroz, Maria Eliana L. R.; Silvério, Flaviano O.

    Resumo em Inglês:

    The lack of accuracy of a chromatographic method can be associated with the matrix effect. This effect is observed in pesticide quantification by gas chromatography when the chromatographic signals of standards prepared in solvents are compared with those of the analyte in extracts of complex matrices. In the competition between the matrix components and the pesticides for the active sites of the liner, a larger amount of pesticides is transferred to the column, giving apparent extractions above 100%. In this work, we discuss factors that contribute to the matrix effect and present some attempts to overcome the problem.
  • Resíduos de agrotóxicos em alimentos: uma preocupação ambiental global - Um enfoque às maçãs Revisão

    Jardim, Isabel Cristina Sales Fontes; Andrade, Juliano de Almeida; Queiroz, Sonia Claudia do Nascimento de

    Resumo em Inglês:

    This paper describes the use of pesticides in agriculture. Research has shown that significant quantities of pesticide residues have been found in many types of foods. Thus, an overview is given of pesticide residue determinations in fruits and vegetables, with special attention to apples. The toxicity and the adverse effects possibly caused by the exposure of these compounds are alerting the scientific community to develop studies about the validation of analytical methods for multiresidue pesticide determination in these samples. This review shows that pesticide-residue determination in apples is becoming a very important and challenging issue.
  • Aspectos mecanísticos da bioatividade e toxicidade de nitrocompostos Revisão

    Paulai, Fávero Reisdorfer; Serrano, Silvia Helena Pires; Tavares, Leoberto Costa

    Resumo em Inglês:

    Nitrocompounds are bioactive molecules used as antibacterial, antiparasitic and antitumoral agents. In the past of years, these molecules have been broadly studied in several fields, such as medicinal chemistry, organic chemistry, biochemical, toxicology and electrochemistry. The nitrocompounds mode of action involves the biotransformation of the nitro group, releasing intermediates in the redox process. Some of those intermediates attack enzymes, membranes and DNA, providing the basis for their biological activity and adverse effects. In this report, some aspects regarding the biological activity, mechanism of action and toxicity of nitrocompounds are explored, purposing the research of new bioactive derivatives having low toxicity.
  • Validação em métodos cromatográficos para análises de pequenas moléculas em matrizes biológicas Revisão

    Cassiano, Neila Maria; Barreiro, Juliana Cristina; Martins, Lúcia Regina Rocha; Oliveira, Regina Vincenzi; Cass, Quezia Bezerra

    Resumo em Inglês:

    Chromatographic methods are commonly used for analysis of small molecules in different biological matrices. An important step to be considered upon a bioanalytical method's development is the capacity to yield reliable and reproducible results. This review discusses validation procedures adopted by different governmental agencies, such as Food and Drug Administration (USA), European Union (EU) and Agência Nacional de Vigilância Sanitária (BR) for quantification of small molecules by bioanalytical chromatographic methods. The main parameters addressed in this review are: selectivity, linearity, precision, accuracy, quantification and detection limits, recovery, dilution integrity, stability and robustness. Also, the acceptance criterions are clearly specified.
  • Termoestabilidade de processos extrativos de Nasturtium officinale R. Br., brassicaceae por sistema Soxhlet modificado Nota Técnica

    Carvalho, João Luiz de Souza; Cunico, Miriam Machado; Dias, Josiane de Fátima Gaspari; Miguel, Marilis Dallarmi; Miguel, Obdulio Gomes

    Resumo em Inglês:

    This work had as objective verified the term-stability of the Soxhlet modified system with analytical and pharmacothecnical application in extractive processes of Nasturtium officinale. It has proven that the process is thermo-stable. The analysis with analytical have determined 3.606 mg g-1 in chlorogenic acid and 11.813 mg g-1 in rutin (extract 1:20 w/v) and with pharmacotecnical 3.427 mg g-1 in chlorogenic acid and 11.278 mg g-1 in rutin (extract 1:6 w/v). The income of the pharmacothecnical process was inferior to the analytical, suggesting that the pharmacothecnical process would need of at least the double of time in each extraction system.
  • Desenvolvimento de sistemas líquido-cristalinos empregando silicone fluido de co-polímero glicol e poliéter funcional siloxano Nota Técnica

    Chorilli, Marlus; Prestes, Paula Souza; Rigon, Roberta Balansin; Leonardi, Gislaine Ricci; Chiavacci, Leila Aparecida; Scarpa, Maria Virgínia

    Resumo em Inglês:

    For the construction of the phase diagrams, the method of the aqueous titration was used. There were prepared 5 ternary diagrams, varying the surfactant and the oil phase. The liquid-crystalline phases were identified by polarized light microscopy. The formulations prepared with silicon glycol copolymer, polyether functional siloxane (PFS) and water (S1) and with diisopropyl adipate, PFS and water (S4) presented liquid-crystalline phases with lamellar arrangement. Moreover, after 15 days in hot oven (37 ºC), the formulations presented hexagonal arrangement, evidencing the influence of the temperature in the organization of the system.
  • Estratégias de pré-concentração em eletroforese capilar (CE): parte 1. Manipulação da velocidade eletroforética do analito Nota Técnica

    Moraes, Maria de Lourdes Leite de; Moraes, Solange Leite de; Pereira, Elisabete Alves; Tavares, Marina Franco Maggi

    Resumo em Inglês:

    Capillary electrophoresis has become a well-established and routine-based separation technique. It is based on the differences between charged analyte mobility in aqueous or organic electrolytes. Its major limitation is the sensitivity due to small sample injection volumes and the narrow diameter of the capillaries, especially when UV detection is used. There are a number of ways to increase the concentration sensitivity. This report shows some on-line preconcentration strategies to perform it in free solution capillary electrophoresis that are based on manipulation of the analyte electrophoretic velocity during the sample introduction (stacking, field amplification and transient isotachophoresis).
  • Biofouling e biodeterioração química de argamassa de cimento portland em reservatório de usina hidroelétrica Nota Técnica

    Portella, Kleber Franke; Joukoski, Alex; Silva, Ariel Scheffer da; Brassac, Nicole Machuca; Belz, Carlos Eduardo

    Resumo em Inglês:

    Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m². Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.
  • Validation of a simple and rapid UV spectrophotometric method for dexamethasone assay in tablets

    Friedrich, Rossana Barcellos; Ravanello, Aline; Cichota, Luiz Carlos; Rolim, Clarice Madalena Bueno; Beck, Ruy Carlos Ruver

    Resumo em Inglês:

    This work reports the validation of an analytical UV spectrophotometric method to assay dexamethasone in tablets (assay and dissolution studies). The method was linear in the range between 1 and 30 µg mL-1 presenting a good correlation coefficient (r = 0.9998, n = 7). Precision and accuracy analysis showed low relative standard deviation (< 2.00%) and good percentual recoveries (95-105%). The procedure was linear, accurate, precise, and robust. The method is simple, and it has low cost. It does not use polluting reagents and can be applied in dissolution studies, being an adequate alternative to assay dexamethasone in tablets.
  • Construção artesanal de um eletrodo íon seletivo a chumbo(II): uma alternativa para disciplinas experimentais Educação

    Silva, Jonatas Gomes da; Lehmkuhl, Arilson; Alcanfor, Silvia Keli de Barros

    Resumo em Inglês:

    This works proposes a homemade construction of a lead(II) ISE of solid membrane (Ag2S/PbS) to determine Pb2+ ions in potentiometric titrations, using damaged combined glass electrodes. This electrode can be constructed in teaching laboratories, using it as a learning tool related to the theoretical principle of ISE. The analytical curve obtained (y = 27.056x + 337.58; R = 0.996) was linear on the range of 1 x 10-5 to 1 mol L-1 and has presented a very close behavior of the Nernstian. The homemade ISE has presented a similar selectivity to the commercial electrodes, showing to be a good alternative to the experimental activities on teaching laboratories.
  • Sistemas tampão: uma estrutura didática teórico-prática Educação

    Rossi-Rodrigues, Bianca Caroline; Oliveira, Elaine Aparecida de; Galembeck, Eduardo

    Resumo em Inglês:

    Courses with practical and theoretical classes are potentially didactic structures for the development of motor and complex cognitive skills when operated in an integrated manner. When worked aligned, theory and practice enable a clearer view of the issue, opening scope for introducing concepts from other disciplines and for the development of lab skills. This paper presents a methodology for biochemistry labwork that promotes the teaching of the buffering systems contents together with to the development of scientific research practice concepts in an interdisciplinary perspective that integrates theory and practice.
  • Eletrodo de hidrogênio: o que há nos livros didáticos além de E¸ = 0? Educação

    Oliveira, Wanda de; Tiedemann, Peter Wilhelm; Cecchini, Renato Giovanni; Osorio, Viktoria Klara Lakatos

    Resumo em Inglês:

    The results of an exercise on electrochemistry for General Chemistry students are presented. The difficulty encountered by students in predicting the shift in the potential of the hydrogen electrode under non-standard conditions prompted a search in textbooks on how the subject is developed. Besides several instances of inconsistencies in defining the standard state, such as including the temperature in the definition, a number of incorrect depictions of the hydrogen electrode were discovered. Of the 28 General Chemistry books, 16 Physical Chemistry books and 24 Internet pages, 30, 20 and 46%, respectively, showed devices that would not work in practice.
  • Preparação do (+)-±-terpineol a partir do (+)-limoneno: monoterpenos de odor agradável em um projeto para química orgânica experimental Educação

    Baptistella, Lúcia Helena Brito; Imamura, Paulo Mitsuo; Melo, Leandro Vilela de; Castello, Cláudio

    Resumo em Inglês:

    A synthesis of (+)-±-terpineol from (+)-limonene was proposed as a project for undergraduate organic laboratory course. Terpineol is a useful flavor and fragrance compound, and several aspects of this preparation are suited for experimental organic classes, including basic techniques for extraction and analyses of essential oils, different reaction types and the possibility of a high degree of student interest.
  • Controvérsias sobre o atomismo no século XIX Assuntos Gerais

    Oki, Maria da Conceição Marinho

    Resumo em Inglês:

    The present article reviews aspects of the controversy in nineteenth-century physical sciences between atomists and anti-atomists, and the scientific, philosophical and methodological aspects about the atomic debates. The meanings of the atom concept used by physicists and chemists in that century are also discussed.
  • Desempenho analítico de laboratórios prestadores de serviço na determinação de metais em águas Assuntos Gerais

    Jardim, Wilson F.; Sodré, Fernando F.

    Resumo em Inglês:

    Analytical laboratories are expected to produce reliable results. Decision makers are guided in their actions (financial, legal and environmental) using analytical data provided by numerous laboratories. This work aimed to evaluate the analytical performance of Brazilian laboratories on producing trustworthy results. Nineteen laboratories, accredited and non-accredited ones, were contracted to analyze a USGS (United States Geological Survey) certified water sample for 17 chemical elements (mostly metals) without knowing the origin of the sample. Considering all the results produced, only 35% of them were valid. Three laboratories present satisfactory performances, whereas the majority showed a very poor overall performance. The outcomes of this work show the need for a more effective analytical quality program to Brazilian laboratories.
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