Química Nova, Volume: 35, Issue: 5, Published: 2012
  • No 35º Aniversário, encerra-se mais uma gestão da SBQ: 2010-2012 Editorial

    Zucco, César; Andricopulo, Adriano D.
  • Sorption and leaching of thiamethoxam in soils treated with sewage sludge and cultivated with Coffee arabica Artigo

    Magalhães, Ciro Augusto de Souza; Lima, José Maria de; Costa, Alisson Lucrécio da; Silva, Evânia Geralda da; Silva, Carlos Alberto; Bettiol, Wagner; Nóbrega, Julio Cesar Azevedo; Guimarães, Paulo Tácito Gontijo

    Abstract in English:

    The objective of this study was to evaluate the sorption and leaching of thiamethoxam in dystrophic Red-Yellow Latosol (LVAd), dystroferric Red Latosol (LVdf) and Red-Yellow Argisol (PVAd) with coffee under the effect of sewage sludge doses. There was thiamethoxam sorption decreasing at higher doses of sewage sludge in LVAd and LVdf. In the PVAd, sorption was higher in samples that received the highest dose of sewage sludge. At 150 days after the application of thiamethoxam, the compound began to be detected in the effluent, in all soils. Dissolved organic carbon had no influence on the thiamethoxam leaching.
  • Synthesis and characterization of Fe(III)-piperazine-derived complexes encapsulated in zeolite Y

    Berezuk, Márcio E.; Paesano Jr., Andrea; Carvalho, Nakédia M. F.; Horn Jr., Adolfo; Arroyo, Pedro A.; Cardozo-Filho, Lúcio

    Abstract in English:

    Zeolite-encapsulated complexes have been widely applied in hydrocarbon oxidation catalysis. The "ship-in-a-bottle" encapsulation of iron(III) complexes containing piperazine and piperazine-derivative ligands in zeolite-Y is described. The flexible ligand methodology was employed and the efficiency and reproducibility of the procedure was investigated. The catalysts were characterized employing several techniques and the results indicate the presence of coordinated and uncoordinated iron(III) ions inside and outside the zeolitic cage.
  • Layered double hydroxides produced from blast furnace slag Artigo

    Rebelo, Monaliza Maia; Cunha, Márcia Valéria Porto de Oliveira; Corrêa, José Augusto Martins

    Abstract in English:

    Hydrotalcite like compounds (HT) were prepared by co-precipitation (Mg/Al = 3.5), using an acid solution with blast furnace slag and MgCl2.6H2O and aqueous solutions of NaOH. The following synthesis variables were investigated: temperature (30 and 45 ºC) and pH (9 and 12). Depending of the temperature two systems were observed: Mg-Al-CO3 (T = 30 ºC); Mg-Al-Cl-CO3 (T = 45 ºC). An increase in the pH of synthesis and Mg2+ concentration produced HTs well-crystallized and with greater values of all cell parameters. The study showed the potentiality of BFS in the synthesis of well-crystallized LDHs without the presence of other crystalline phases.
  • Descoloration of industrial dyes and simulated textile effluents dyes by turnip peroxidase Artigo

    Silva, Maria Cristina; Corrêa, Angelita Duarte; Torres, Juliana Arriel; Amorim, Maria Teresa Sousa Pessoa

    Abstract in English:

    The removal of important textile dyes by turnip peroxidase (TNP) was evaluated. The textile effluents besides the residual dyes contain also chemical auxiliaries such as salts, dispersing and wetting agents. The effect of these was evaluated in the removal of the dyes reactive blue 21 and reactive blue 19 by TNP in synthetic effluents. A decrease of the efficency decolorization was observed. The action of the enzyme on colour removal of dye mixture was equivalent to the dyes alone. The chemical demand of oxygen in the effluent after enzymatic treatment had a significant increase in relation to the untreated effluent.
  • Photoelectrochemical degradation of reactive blue 19 in aqueous solutions Artigo

    Jacobs, Loraine C. V.; Peralta-Zamora, Patricio G.

    Abstract in English:

    In this work the degradation capacity of a photo-electrocatalytic system was evaluated, mainly regarding the effect of the electrolyte solution on the degradation capacity toward a reactive textile dye. In the presence of NaCl the photo-electrochemical process shows high degradation efficiency, permitting almost total color removal in treatment of about 5 min. In view of the low degradation efficiency observed for the photocatalytic process it is possible to assume that the high degradation efficiency of the process is a function of electrochemical generation of oxidant active chlorine species, which are subsequently transformed to higher oxidant radical forms.
  • UV/H2O2 process as post-treatment for removal of color and polishing end in textile wastewater Artigo

    Nagel-Hassemer, Maria Eliza; Coral, Lucila Adriani; Lapolli, Flávio Rubens; Amorim, Maria Teresa Souza Pessoa de

    Abstract in English:

    Several problems are involved the treatment plants of textile effluents, mainly the low efficiency of color removal. This paper presents an alternative of post-treatment by UV/H2O2 process, for color removal in biologically treated textile effluents. The tests were performed in a photochemical reactor and samples were taken at different times to perform analyses. Using 250 mgH2O2.L-1, 96% removal of color was verified, indicating the dyes degradation. A reduction of 84% of aromatics compounds, 90% of TSS removal, and a further reduction of the organic fraction were observed, demonstrating that the process is effective as a post-treatment of effluents from textile industries.
  • Biomonitoring of Cr and Pb in freshwater fish Artigo

    Repula, Carolina Marília Martins; Campos, Bruna Kauely de; Ganzarolli, Edgard Moreira; Lopes, Mauro Chierici; Quináia, Sueli Pércio

    Abstract in English:

    Trace metal content of three fish species harvested from a tank located in the City of Guarapuava-PR, Brazil were determined by digestion and voltametry. Trace metal content in fish samples were 0.10-1.30 µg/g (muscle) and 0.45-15.90 µg/g (liver) for chromium, 0.35-2.56 µg/g (muscle) and 2.32-34.30 µg/g (liver) for lead. The levels of lead and chromium in fish samples were higher than the recommended legal limits for human consumption. To assess the dietary intake of Cr and Pb by fish, weekly intake was calculated based on average metals contents and weekly consumption of fish and it compared with PTWI (Provisional Tolerable Weekly Intake). The Cr and Pb have achieved up to 25 and 45%, respectively, of PTWI recommended by WHO/FAO.
  • Parametric sensitivity analysis for the helium dimers on a model potential

    Lemes, Nelson Henrique Teixeira; Viterbo, Vitor D.; Sebastião, Rita C. O.; Braga, João P.

    Abstract in English:

    Potential parameters sensitivity analysis for helium unlike molecules, HeNe, HeAr, HeKr and HeXe is the subject of this work. Number of bound states these rare gas dimers can support, for different angular momentum, will be presented and discussed. The variable phase method, together with the Levinson's theorem, is used to explore the quantum scattering process at very low collision energy using the Tang and Toennies potential. These diatomic dimers can support a bound state even for relative angular momentum equal to five, as in HeXe. Vibrational excited states, with zero angular momentum, are also possible for HeKr and HeXe. Results from sensitive analysis will give acceptable order of magnitude on potentials parameters.
  • Synthesis of 2-azetidinone derivatives of 6-nitro-1H-indazole and their biological importance

    Samadhiya, Pushkal; Sharma, Ritu; Srivastava, Santosh K.; Srivastava, S. D.

    Abstract in English:

    A new series of 3-chloro-1-{[2-(6-nitro-1H-indazol-1-yl)ethyl]amino}-4-(substituted phenyl)-2-azetidinones (4a-j) was synthesized in four steps from 6-nitro-1H-indazole and characterized by IR, ¹H NMR, 13C NMR, FAB-mass spectrometry and chemical methods. Compounds 4(a-j) were screened in vitro for their antibacterial, antifungal and antitubercular activities against some selected microorganism and for their antiinflammatory activity (in vivo) against albino rats (either sex). All above activities of compounds 4(a-j) showed acceptable results.
  • Surface energy for (001) TiO2 nanosurfaces Artigo

    Lazaro, Sergio de; Penteado, Renato Ferras; Tebcherani, Sergio Mazureck; Berger, Danielle; Varela, José Arana; Kubaski, Evaldo Toniolo

    Abstract in English:

    In this work was made an investigation about bulk and surface models (at maximum 20 layers) of the TiO2 material in the (001) direction. TiO2 commercial sample was feature using XDR technique to determine phase and crystallites average size. Bulk and (001) surface models were simulated for TiO2 material using DFT/B3LYP and its results were used for calculating energy surface, electronic levels, superficial atomic displacement and charge maps. Atoms of the first and second layers of the slab model showed electronic densities very well organized in the form of chains or wires.
  • Study of metal contamination in aquatic sediments of the Bay of Matanzas

    Quevedo, Odalys; Gómez, Jorge; Ramírez, Carmen; Estrada, Tamara; Moreno, Carlos; Mendiguchía, Carolina; Villanueva Tagle, Margarita Edelia; Pomares Alfonso, Mario Simeón

    Abstract in English:

    Surface sediments of the Bay of Matanzas (Cuba) were studied to assess its environmental quality by using several criteria (metal content index, pollution load index and sediment quality guidelines). Two partial digestion sediment procedures and a modified BCR sequential extraction were used. The concentrations of metals were measured by atomic spectroscopy methods. The founded contents of Cu (2,4-27,9 mg kg-1), Zn (2,5-55,5 mg kg-1) and Ni (8,8-99,2 mg kg-1) were below those reported by other authors. The results obtained suggested that the most polluted sites were 3, 5, and 6. The sequential extraction procedure showed that most of the studied metals were associated to the more stable fractions.
  • Degradation of textile dyes and remediation of dying residues by Fenton, photo-Fenton and electro-Fenton processes Artigo

    Salvador, Terezinha; Marcolino Jr., Luiz H.; Peralta-Zamora, Patricio

    Abstract in English:

    In this work the degradation of textile dyes were evaluated, using Fenton, photo-Fenton and electro-Fenton processes. Under optimized conditions Fenton and photo-Fenton processes showed high decolorization capacity of the model dyes. The electro-Fenton process was carried out in an undivided electrochemical reactor (1000 mL) equipped with a carbon-felt cathode (253 cm²) and a platinum gauze anode (6 cm²). Under optimal conditions (J: 1.6 mA cm-2, Na2SO4: 0.075 mol L-1, pH: 3) H2O2 concentration of about 60 mg L-1 was observed. The addition of Fe2+ (15 mg L-1) induces Fenton reactions that permit almost total decolorization of textile dyes.
  • Simultaneous determination of non-steroidal anti-inflammatory drugs in pharmaceutical formulations and human serum by reversed phase high performance liquid chromatography

    Nawaz, Muhammad

    Abstract in English:

    A rapid and sensitive method using high performance liquid chromatography has been developed and validated for the simultaneous determination of non-steroidal anti-inflammatory drugs (NSAIDs) in pharmaceutical formulations and human serum. Six NSAIDs including: naproxen sodium, diclofenac sodium, meloxicam, flurbiprofen, tiaprofenic and mefenamic acid were analyzed simultaneously in presence of ibuprofen as internal standard on Mediterranea C18 (5 µm, 250 x 0.46 mm) column. Mobile phase comprised of methanol: acetonitrile: H2O (60:20:20, v/v; pH 3.35) and pumped at a flow rate of 1 mL min-1 using 265 nm UV detection. The method was linear over a concentration range of 0.25-50 µg mL-1 (r² = 0.9999).
  • Dereplication of aporphine and oxoaporphine alkaloids from Unonopsis guatterioides BY ESI-IT-MS Artigo

    Silva, Felipe Moura Araújo da; Koolen, Hector Henrique Ferreira; Almeida, Richardson Alves de; Souza, Afonso Duarte Leão de; Pinheiro, Maria Lúcia Belém; Costa, Emmanoel Vilaça

    Abstract in English:

    The dereplication of aporphine and oxoaporphine alkaloids by direct infusion in ESI-IT-MSn system was applied for alkaloidal fractions of the Unonopsis guatterioides (Annonaceae). Its main advantage over other dereplication methods is the ability to quickly identify substances in complex mixtures without the use of coupled techniques and expensive databases. By only the fragmentation keys and comparison with literature data the aporphine alkaloids anonaine, asimilobine and nornuciferine were identified. The nornuciferine is being reported for the first time in Unonopsis. The oxoaporphine alkaloids liriodenine and lisycamine were identified in the alkaloidal fractions by comparison with the fragmentations of authentic samples.
  • Synthesis and antifungal activity of halogenated aromatic bis-γ-lactones analogous to avenaciolide

    Castelo-Branco, Pedro A.; Rubinger, Mayura M. M.; Alves, Leandro de C.; Liberto, Natalia A.; Nepel, Thayane C. M.; Catrinck, Mariana; Guilardi, Silvana; Silvério, Hudson A.; F. Neto, Wilson P.; Zambolim, Laércio; Piló-Veloso, Dorila

    Abstract in English:

    Here we describe the total syntheses and characterization by elemental analyses, infrared and NMR spectroscopy of three new compounds analogous to avenaciolide, a bis-γ-lactone isolated from Aspergillus avenaceus that possesses antifungal activity, where the octyl group of the natural product was replaced by aromatic groups containing chlorine and fluorine atoms. The effects of the avenaciolide, the novel compounds and their synthetic precursors on mycelia development and conidia germination of Colletotrichum gloeosporioides and Fusarium solani were evaluated in vitro. The title compounds were almost as active as avenaciolide. The absolute structures of the chlorinated analogs were determined by X-ray diffraction analysis.
  • Synthesis and characterization of aba-type copolymers for encapsulation of bovine hemoglobin Artigo

    Lima, Felipe F.; Andrade, Cristina T.

    Abstract in English:

    The use of biopolymers for the development of oxygen carriers has been extensively investigated. In this work, three different ABA triblock copolymers were synthesized and used to encapsulate purified bovine hemoglobin, using a double emulsion technique. The effect of polymer composition, homogenization velocity, and addition of a surfactant, on the protein entrapment was evaluated. These copolymers, which have a hydrophilic block, achieved higher values of encapsulation efficiency than the corresponding homopolymers. The increase in homogenization strength also promoted an increase in encapsulation efficiency. Capsules formation occurred even in the absence of PVA.
  • Factors governing the formation of THE β-PbO2 phase electroformed galvanostatically on the carbon cloth substrate Artigo

    Costa, Fabiano Ramos; Silva, Leonardo Morais da

    Abstract in English:

    PbO2 films were electroformed onto carbon cloth substrates (twill woven type) in acid conditions using the nitrate precursor by changing the electrodeposition current density, temperature and pH, in order to optimize the formation of the β-PbO2 phase. The crystal structure and morphology of the PbO2 films were investigated using X-ray diffraction (XRD) and scanning electronic microscopy (SEM) techniques. The optimum conditions obtained for formation of the β-PbO2 were presented and discussed.
  • Development of methodology to determine estrogens in wastewater treatment plants Artigo

    Pessoa, Germana de Paiva; Santos, André Bezerra dos; Souza, Neyliane Costa de; Alves, Joana Angélica Correia; Nascimento, Ronaldo Ferreira do

    Abstract in English:

    The present research aimed to study the parameters that affect the determination of estrogens in sewage upon the use of SPE and determination by using gas chromatography mass spectrometry (GC/MS). The study evaluated the stabilization pond technology with regard to estrogens removal. The results showed that the methodology was able to identify and quantify the estrogens E1, E2, E2-17A and EE2 in sewage. Moreover, the estrogens sometimes were not removed in the stabilization pond, showing that even the high hydraulic retention time (HRT) and high sunlight intensity were not enough to degrade these compounds completely during load peaks.
  • Chemical study of Sinningia allagophylla guided by antiproliferative activity assays Artigo

    Riva, Dilamara; Barison, Andersson; Stefanello, Maria Élida Alves; Poliquesi, Clarisse Bolfe; Ruiz, Ana Lúcia Tasca Goes; Carvalho, João Ernesto de; Salvador, Marcos José

    Abstract in English:

    Activity guided fractionation of Sinningia allagophylla (Mart.) Wiehler ethanolic extract yielded a new benzochromene 8-methoxylapachenol, besides seven known compounds: lapachenol, sitosteryl oleate, sitosteryl linoleate, stigmasteryl oleate, stigmasteryl linoleate, dunniol and tectoquinone. Extract, fractions, and compounds lapachenol, 8-methoxylapachenol, and dunniol were tested in vitro against human cancer cell lines U251 (glioma, CNS), MCF-7 (breast), NCI-ADR/RES (drug-resistant ovarian), 786-0 (kidney), NCI-H460 (lung, no small cells), PC-3 (prostate), OVCAR-3 (ovarian), HT-29 (colon), K562 (leukemia) and against VERO, a normal cell line. The most active compound was dunniol, which inhibited the growth of U251, MCF-7, NCI-ADR/RES, OVCAR-3 and K562 cell lines.
  • Investigating the spontaneous formation of SDS micelle in aqueous solution using a coarse-grained force field

    Pires, José Maria; Moura, André F. de; Freitas, Luiz C. G.

    Abstract in English:

    A 1µs Molecular Dynamic simulation was performed with a realistic model system of Sodium Dodecyl Sulfate (SDS) micelles in aqueous solution, comprising of 360 DS-, 360 Na+ and 90000 water particles. After 300 ns three different micellar shapes and sizes 41, 68 and 95 monomers, were observed. The process led to stabilization in the total number of SDS clusters and an increase in the micellar radius to 2.23 nm, in agreement with experimental results. An important conclusion, is be aware that simulations employed in one aggregate, should be considered as a constraint. Size and shape distribution must be analyzed.
  • Specificity and selectivity improvement in doping analysis using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry

    Barbosa, Samantha S.; Leal, Felipe D.; Padilha, Monica C.; Silva, Raphael S. F.; Pereira, Henrique Marcelo G.; Aquino Neto, Francisco R.; Silva Júnior, Ademário I. da

    Abstract in English:

    Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was used for the identification of forty doping agents. The improvement in the specificity was remarkable, allowing the resolution of analytes that could not be done by one-dimensional chromatographic systems. The sensitivity observed for different classes of prohibited substances was clearly below the value required by the World Anti-Doping Agency. In addition time-of-flight mass spectrometry gives full spectrum for all analytes without any interference from the matrix, resulting in selectivity improvements. These results could support the implementation of an exhaustive monitoring approach for hundreds of doping agents in a single injection.
  • Voltammetric determination of sibutramine in beverages and in pharmaceutical formulations

    Carvalho, Juliana M.; Silva, Andrea R. da; Cunha, Alessandra L. M. C. da; Aucélio, Ricardo Q.; Alberti, André Luis M.; Leandro, Katia C.

    Abstract in English:

    A simple and sensitive method has been proposed for the determination of sibutramine-HCl in energy drinks, green tea and pharmaceutical formulations using differential pulse voltammetry performed on a hanging mercury drop electrode. In the chosen experimental condition (Mcllvaine pH 4.0 buffer, 50 mV pulse amplitude and 40 mV s-1 scan velocity), sibutramine-HCl presented a reversible behavior and a peak maximum at -80 mV. Detection limit was 0.4 mg L-1 and the working linear range extended up to 33.3 mg L-1 (r = 0.99). Analysis of real and fortified samples enabled recoveries between 91 and 102%. The electroanalytical method was compared with a HPLC method which indicated it accuracy.
  • The challenges of the analysis of basic solutes by reversed phase liquid chromatography: some possible approaches for improved separations Revisão

    Borges, Endler Marcel; Goraieb, Karen; Collins, Carol H.

    Abstract in English:

    This review considers some of the difficulties encountered with the analysis of basic solutes using reversed-phase chromatography, such as detrimental interaction with stationary phase silanol groups. Methods of overcoming these problems in reversed-phase separations, by judicious selection of the stationary phase and mobile phase conditions, are discussed. Developments to improve the chemical and thermal stability of stationary phases are also reviewed. It is shown that substantial progress has been made in the manufacturing of stationary phases, enabling their use over a wide variety of experimental conditions. In addition, general measures to significantly extend their lifespan are discussed.
  • Potential of sugarcane straw for ethanol production Revisão

    Santos, Fernando A.; Queiróz, José H. de; Colodette, Jorge L.; Fernandes, Sergio A.; Guimarães, Valéria M.; Rezende, Sebastião T.

    Abstract in English:

    Sugarcane straw biomass accounts for 1/3 of the energy potential of sugarcane and represents a rich source of sugars. Studies have been intensified for the use of this biomass along with bagasse for the production of cellulosic ethanol. Development of this technological path will allow for taking full advantage of sugarcane, increasing ethanol production without expanding the area cultivated. However, in order for this technology to be viable certain challenges must be overcome, including establishment of appropriate conditions of pretreatment and hydrolysis of these materials for release of fermentable sugars.
  • Certified reference material to water content determination in bioethanol fuel

    Rodrigues, Janaína M.; Guimarães, Evelyn F.; Sousa, Marcus V. B.; Silva, Viviane F.; Fraga, Isabel C. S.; Souza, Vanderléa; Cunha, Valnei S.

    Abstract in English:

    Bioethanol is a strategic biofuel in Brazil. Thus, a strong metrological basis for its measurements is required to ensure the quality and promote its exportation. Recently, Inmetro certified a reference material for water content in bioethanol. This paper presents the results of these studies. The characterization, homogeneity, short-term stability and long-term stability uncertainty contributions values were 0.00500, 0.0166, 0.0355 and 0.0391 mg g-1, respectively. The certificated value for water content of bioethanol fuel was (3.65 ± 0.11) mg g-1. This CRM is the first and up to now the unique in the world.
  • Construction and application of a bismuth-film mini sensor using low cost materials for in loco voltammetric determinations Nota Técnica

    Figueiredo-Filho, Luiz Carlos S.; Janegitz, Bruno C.; Faria, Ronaldo C.; Fatibello-Filho, Orlando; Marcolino-Junior, Luiz H.; Caetano, Fabio Roberto; Mattos, Ivanildo Luiz de

    Abstract in English:

    The construction of a low cost mini sensor containing a bismuth-film electrode (BiFE), as work electrode, a silver electrode as pseudo reference electrode, and copper as counter electrode is proposed. The application of this mini sensor using a low cost electrochemical cell for in loco voltammetric determinations of inorganic and organic analytes is also described.
  • Quantification of L-ascorbic acid and D-iso-ascorbic acid in jellies fruit by high performance liquid chromatography Nota Técnica

    Oliveira, Raquel Grando de; Godoy, Helena Teixeira; Prado, Marcelo Alexandre

    Abstract in English:

    Ascorbic acid has important nutritional characteristics such as high antioxidant potential, preventing diverse damage and diseases in the tissues and the process of aging. Different isomeric forms of the ascorbic acid can be found in nature and each one have different potential antioxidant and different activity pro-vitamin C. This work examined a method to detect and quantify the isomers L-ascorbic acid (LAA) and D-iso-ascorbic acid (DIAA) in jelly fruit. The method showed acceptable selectivity, linearity, repeatability and recovery. DIAA was not found in the analyzed samples, but LAA was found up to 605 mg in 100 g of sample.
  • A fluorescence-based assay for octreotide in kinetic release from depot formulations

    Guerreiro, Luiz Henrique; Girad-Dias, Wendell; Miranda, Kildare R. de; Lima, Luís Mauricio T. R.

    Abstract in English:

    Here we report the validation of a derivatization method that makes use of fluorescamine as a selective reactant for the quantitative analysis of peptide and protein drugs in the dissolution profile from depot formulations. Typical current methods require separation of the nano/microparticles and time-consuming chromatographic runs. In this study we report a method which can be conducted without the need for complete physical separation of the particles or removal of the unreacted probe. This method was used here for the analysis of the release profile of octreotide in a depot formulation, with results in excellent agreement with reported chromatographic assays.
  • Development and validation of analytical method for determination of tibolone in capsules by high performance liquid chromatography Nota Técnica

    Rosa, Hernandez Bozardi da; Tolotti, Renata Cristine; Miron, Diogo dos Santos; Souza, Kellen Cristhinia Borges de

    Abstract in English:

    Tibolone is a synthetic steroid used for prevention of bone loss and treatment of menopause symptoms. This article describes the development and validation of an analytical method to quantify tibolone in capsules using high performance liquid chromatography with UV detection. After chromatography conditions are established the validation parameters evaluated were specificity, linearity, precision, accuracy, detection and quantification limits and robustness. The method developed is effective to analyze tibolone in capsules, being able to be used in quality control laboratory routine.
  • Development and validation of a HPLC method for quantification of ursolic acid in solid dispersions Nota Técnica

    Eloy, Josimar de Oliveira; Oliveira, Erika Cristina Vargas de; Marotta-Oliveira, Samantha Sant'Anna; Saraiva, Juliana; Marchetti, Juliana Maldonado

    Abstract in English:

    Ursolic acid is a natural molecule that presents several pharmacological properties. In this work, an analytical method by RP-HPLC has been developed and validated for quantification of this drug in the solid dispersions, using PEG 6000 and Poloxamer 407 as polymers. The method was specific, linear in the range of 1.0-50.0 µg mL-1 (r<0.99), precise (CV < 5% for both inter- and intra-assays), accurate (maximum deviation of ± 13%), and robust to the parameters evaluated. This method has proved to be simple and useful for ursolic acid determination in solid dispersions, enabling its determination in pharmaceutical dosage form.
  • Isolation and quantitative HPLC-PDA analysis of lupeol in phytopharmaceutical intermediate products from Vernonanthura ferruginea (Less.) H. Rob.

    Oliveira, Ezequiane Machado Silva; Freitas, Sabrine Lemes; Martins, Frederico Severino; Couto, Renê Oliveira; Pinto, Mariana Viana; Paula, José Realino; Conceição, Edemilson Cardoso; Bara, Maria Teresa Freitas

    Abstract in English:

    Prior to obtain a standardized dried extract from V. ferruginea, lupeol was first time isolated from leaves and used as chemical maker. An analytical method using HPLC-PDA for lupeol determination in V. ferruginea intermediate products was developed using a C8 reverse-phase column, acetonitrile-acetic acid (99.99:0.01, v/v) as mobile phase at 0.8 mL min-1, oven temperature at 23-25 ºC, sample injection volume at 30 µL and detection at 210 nm. The method presented linearity from 10 to 160 µg mL-1, accuracy, precision, robustness and suitable sensitivity proving to be a useful tool to the obtainment process of lupeol standardized dried extracts of V. ferruginea.
  • Furfural - from biomass to organic chemistry laboratory Educação

    Ribeiro, Paulo Roberto; Carvalho, José Roque Mota; Geris, Regina; Queiroz, Vinícius; Fascio, Miguel

    Abstract in English:

    The goal of this manuscript is provide to students of Chemistry and related areas an alternative experiment in which they can obtain a compound and learn to observe and interpret properties and predict organic structure by obtaining furfural from biomass. Furfural is an organic compound, obtained through acid hydrolysis of pentosans, commonly used in the chemical and pharmaceutical industries. Students are guided to get furfural through extractive procedures and chemical reactions adapted to semi-micro laboratory scale. Characterization of furfural was done by chemical tests and physical properties. Identification was accomplished by a series of spectroscopic and spectrometric techniques.
  • Strategies for studying free-energy correlations of Suzuki aryl-aryl coupling: elucidating catalytic cycles by way of the Hammett equation Educação

    Rosa, Gilber Ricardo

    Abstract in English:

    The present work deals with the study of the correlation of free-energy developed in a catalytic system for Suzuki coupling, by way of the Hammett equation. The system presents NCP pincer palladacycle 1 as a catalyst precursor, which proved to be very efficient in the coupling of various aryl boronic acids with aryl halides in previous studies. Thus, the article presented here intends to serve as a support for further investigations and clarifications relating to cross-coupling catalytic cycles.
  • The second law of thermodynamics Educação

    Reis, Martina Costa; Bassi, Adalberto Bono Maurizio Sacchi

    Abstract in English:

    Considering intrinsic characteristics of the system exclusively, both statistical and information theory interpretations of the second law are used to provide more comprehensive meanings for the concepts of entropy, temperature, and Helmholtz and Gibbs energies. The coherence of Clausius inequality to these concepts is emphasized. The aim of this work is to re-discuss the second law of thermodynamics in accordance to homogeneous processes thermodynamics, a temporal science which is the very special oversimplification of continuum mechanics for spatially constant intensive properties.
  • Metalloids in origin and evolution of life Assuntos Gerais

    Aureliano, Manuel; Nolasco, Pedro A.; Silva, João J. R. Fraústo da; Silva, José Armando L. da

    Abstract in English:

    Metalloids have characteristics between metals and non-metals which give them, in some cases, specific properties. At least two of this chemical elements, boron and silicon, are essential to a significant number of living organisms and since some years ago it has been observed that the same metalloids may be involved in the synthesis and stabilization of some molecules relevant to the origin of life.
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