Química Nova, Volume: 32, Issue: 9, Published: 2009
  • O que desejamos para 2010? Editorial

    Ferreira, Vitor F.
  • Toxicity and antioxidant activity of flavonoids from Lonchocarpus filipes root bark Artigo

    Santos, Érica L.; Costa, Emmanoel V.; Marques, Francisco A.; Vaz, Nelissa P.; Maia, Beatriz Helena L. N. Sales; Magalhães, Eva G.; Tozzi, Ana Maria A.

    Abstract in English:

    The phytochemical investigation of dichloromethane extract from root bark of Lonchocarpus filipes Benth (Leguminosae) afforded four flavonoids including three dibenzoylmethane derivatives rarely found in nature. The structures were established based on their spectral data (¹H and 13C NMR, 2D-NMR) as being: lanceolatin B (1), pongamol (2), (E)-7-O-methylpongamol (3) and (E)-9-O-methylpongamol (4). Compound (4) is described herein for the first time as a natural product. The extracts and the isolated compounds (1), (2) and (3) displayed high toxicity in the brine shrimp lethality assay. Only compound (2) showed antioxidant activity using a DPPH radical scavenging assay. This is the first report on the phytochemical study of Lonchocarpus filipes.
  • Sorption of the insecticide thiamethoxam by organic and mineral fraction from a brazilian oxisol Artigo

    Weber, Oscarlina Lúcia dos Santos; Martins, Eucarlos de Lima; Dores, Eliana Freire Gaspar de Carvalho; Curado, Lauro Dormivil de Amorim

    Abstract in English:

    The sorption of thiamethoxam in a Brazilian Oxisol was determined in soil samples with and without organic matter for two different dephs (0-0.1 and 0.4-0.7 m). The results indicated a predominant sorption of thiamethoxam on soil without organic matter. The following Kd values of 4.25 mL g-1 (0-0.1 m, r² = 0.8534) and 5.30 mL g-1 (0.4-0.7 m, r² = 0.9884) and Kf values, 7.65 mL g-1 (0-0.1 m, r² = 0.9623) and 7.72 mL g-1 (0.4-0.7 m, r² = 0.9775) were obtained. Those sorption coefficient values indicated a small interaction between thiamethoxam for both original soil and soil without organic matter.
  • Tribocorrosion of TI6AL4V alloy in phosphate buffered saline solution Artigo

    Manhabosco, Taíse M.; Muller, Iduvirges L.; Santos, Claudia B. dos

    Abstract in English:

    The tribocorrosion behavior of Ti6Al4V alloy was investigated in a Phosphate Buffered Saline (PBS) solution by a reciprocating wear, using alumina ball as the counterface material, at different normal forces and sliding velocities. Dry wear experiments were performed in order to compare with the tribocorrosion experiments at open circuit potential and under anodic polarization. Dry wear induced a superior damage on the counterface, forming larger and shallower wear tracks compared with those experiments performed in PBS solution. The anodic current was increased by wear; however the volume of oxidized metal in tribocorrosion experiments correspond to a relative low percentage of the wear track volume.
  • Enzymatic synthesis isoamyl butyrate employing commercial microbial lipases Artigo

    Aragão, Vitor Cardoso; Anschau, Andréia; Porciuncula, Barbara Daniele Almeida; Thiesen, Cleidi; Kalil, Susana Juliano; Burkert, Carlos André Veiga; Burkert, Janaína Fernandes de Medeiros

    Abstract in English:

    Isoamyl butyrate production was investigated using free and immobilized lipases by esterification of butyric acid with isoamyl alcohol in a solvent-free system and in an organic media. Among the enzymes studied, Lipozyme TL IM was found to be the most active catalyst in n-hexane as a solvent. The effects of different solvents and the amount of water added on conversion rates were studied. A maximum conversion yield of 80% in n-hexano at 48 h was obtained under the following conditions: 3 g L-1 of Lipozyme TL IM, 30 ºC, 180 rpm of agitation, isoamyl alcohol to butyric acid molar ratio of 1:1 and acid substrate concentration of 0.06 M.
  • Rainwater ammonium concentrations and estimate of ammonia emissions from domestic animals in Pinheiro and Viana, Baixada Maranhense Artigo

    Lima, Richardson G.; Cavalcante, Paulo R. S.; Melo, Odilon T.; Mello, William Z. de

    Abstract in English:

    Rainwater samples (bulk deposition samples) were collected in Pinheiro and Viana. Rainwater pHs were higher than the range usually expected for unpolluted rain (5.0-5.6). The highest values were found in the beginning of the rainy season. High concentrations of ammonium found in the rainwater samples could probably explain the high pHs. Grazing animals and other human activities, combined with soil characteristics and climatic conditions can be the potential factors controlling the rainwater concentrations of ammonium in Baixada Maranhense.
  • Potential alternative for using the glycerol generated in the biodiesel production: enzymatic synthesis of monolaurin by esterification Artigo

    Freitas, Larissa; Santos, Julio C.; Barcza, Marcos V.; Castro, Heizir F. de

    Abstract in English:

    Esterification reactions of glycerol with lauric acid in solvent free system were carried out using lipases from several sources. All lipases were immobilized on polysiloxane-polyvinyl alcohol particles by covalent binding with high activity recovered. Among the tested enzymes, the Candida antarctica lipase allowed to attain the highest molar conversion (76%), giving similar proportions of monolaurin, dilaurin and low amount of trilaurin. To further improve the process, the Response Surface Methodology (RSM) was used and optima temperature and molar ratio glycerol to lauric acid were found to be 45 ºC and 5:1, respectively. Under these conditions, 31.35% of monolaurin concentrations were attained and this result was in close agreement with the statistical model prediction.
  • Biodegradability evaluation of textile effluents from the secundary process of polyester fibers treated with Fenton's Reagent Artigo

    Oliveira, Dângelle M.; Leão, Mônica M. D.

    Abstract in English:

    From the environmental point of view, the textile sector is outstanding for the generation of large amounts of biorecalcitrant effluents. In this paper the textile effluent biodegradability, both before and after its treatment with Fenton's Reagent, were compared by means of biologic tests. These tests showed that the Fenton treatment lowered the biodegradabilty of practically all tested effluents, except one specific effluent from a scouring bath of polyester fibers, which achieved a 93% COD removal. This removal was due to a significant phase separation (oil/water).
  • Bentonitic clays of Santa Elena península, Ecuador: al-pilarization, acid-activation and its use in the bleaching of soybean oil Artigo

    Morales-Carrera, Ana M.; Varajão, Angélica F. D. C.; Gonçalves, Marcos A.; Stachissini, Antônia S.

    Abstract in English:

    Two samples of calcic bentonite of the Santa Elena Peninsula, Ecuador, were pillared with Al13 ions in the ratio of 10, 15 and 20 meq of Al g-1 of clay, calcinated at 573, 723 and 873 ºK and acid activated with 4, 6 and 8 mol L-1 H2SO4. Analyses by X-ray diffraction, X-ray fluorescence, differential and gravimetric thermal, density, surface area and porosity, were applied in order to study the modifications occurred in the crystalline structure of the montmorillonite. The 8 mol L-1 H2SO4 acid-activated 15 meq of Al g-1 of clay at 573 ºK Al-pillared samples indicated the best results in the bleaching of the soybean oil measured by UV-visible spectrophotometer.
  • Assessment of the use of polyethylene terephthalate (PET) as matrix for immobilization of incinerator ash Artigo

    Pacheco, Flávia Gonçalves; Cota, Stela Dalva Santos; Silva, Tânia Valéria da; Senne Jr., Murillo

    Abstract in English:

    Industrial hazardous wastes must receive appropriate treatment to ensure a safe disposal to humans and environment. One of the techniques adopted for this purpose is the stabilization/solidification in polymer matrices. This paper evaluated the use of recycled polyethylene terephthalate as an incorporation matrix of incinerator ash. The polymer and the ash were submitted to an extrusion process in different percentages. The final product was evaluated through thermal and leaching tests and the leachate extracts constituents were determinated by atomic absorption spectrophotometry. The results showed a reduction in the release of substances up to 99% by mass for the conditions used.
  • Obtainment and evaluation of protein concentrates of whitemouth croaker (Micropogonias furnieri) processed by chemical extraction Artigo

    Fontana, Aline; Centenaro, Graciela Salete; Palezi, Simone Canabarro; Prentice-Hernández, Carlos

    Abstract in English:

    The objective of this study was to obtain and evaluate physicochemical and functional properties of protein concentrates from Micropogonias furnieri produced by pH shifting process, using alkaline and acid solubilization followed by isoelectric precipitation of muscle proteins. The concentrates showed high protein content and the maxim solubility for the minced (96.5%), for the alkaline (97.5%) and acid (93.7%) extraction was obtained at pH 11.0. The water holding capacity of the alkaline concentrate resulted in a value same or superior to water holding capacity of the acid concentrate in all investigated values of pH. The oil holding capacity of alkaline and acid concentrates showed no significant difference between the studied processes.
  • Organic compounds contents in cachaças produced in the northern Rio de Janeiro State - RJ Artigo

    Souza, Leandro Marelli de; Ferreira, Karla Silva; Passoni, Luís César; Bevitori, Alice Barreto; Melo, Karen Vieira; Viana, Arivaldo Ribeiro

    Abstract in English:

    This work aimed to quantify some organic compounds in "cachaças" (sugar cane spirit). The ethyl alcohol was quantified by densimetry, after distillation. The acetic acid, methyl alcohol, n-propyl alcohol, n-butyl alcohol, isobutyl alcohol, isoamyl alcohol (mixture of 2-methyl-butyl and 3-methyl-butyl), ethyl acetate and acetaldehyde were determined by gas chromatography; and the furfural, 5-hydroxy-methylfurfural and acrolein by high efficiency liquid chromatography. From the 30 samples analyzed, 63.3% showed non-conformity with national legislation regarding at least one of the analyzed components.
  • Characterization of the major nutritional components of Caryocar brasiliense fruit pulp by nmr spectroscopy

    Miranda-Vilela, Ana Luisa; Grisolia, Cesar Koppe; Resck, Inês Sabioni; Mendonça, Márcio Antônio

    Abstract in English:

    Pequi (Caryocar brasiliense Camb.), a typical fruit of Brazilian Cerrado, is well known in regional cookery and used in folk medicine to treat various illnesses. Mass spectrometry and chromatographic methods have identified the organic composition of pequi fruit pulp; however, NMR spectroscopy is used for the first time to characterize the nutritional components of organic and aqueous-ethanolic extracts. This spectroscopic technique determined the triacylglycerols in the pequi organic fraction, which is constituted mainly by oleate and palmitate esters, and detected the carbohydrate mixtures as the major components of aqueous and ethanolic fractions, respectively. In this study, presence of phenolic compounds was only evidenced in the ethanolic fraction.
  • Short-term variations of soil CO2 emissions in coffee plantations Artigo

    D'Andréa, Alexandre Fonseca; Silva, Marx Leandro Naves; Curi, Nilton; Freitas, Diego Antonio França de; Roscoe, Renato; Guimarães, Paulo Tácito Gontijo

    Abstract in English:

    Soil CO2 emissions represent an important component of carbon global cycle. However, information about short-term alterations of CO2 fluxes in soils of tropical regions are scarce. So, the objective of this study was to evaluate such variations in coffee plantations in Latosol (Oxisol). The CO2 emissions were not affected by environmental abiotic factors, such as temperature and soil water evaporation, but they were significantly correlated with the carbon content of microbial biomass (R=0.90, P<0.05). It happens a close relationship between root activity and soil CO2 emission in coffee plantations.
  • Lead(II) removal in continous systems by vapor activated carbon Artigo

    Zanin, Cristiane Imenes de Campos Bueno; Figueiredo, Flávia Camargo Alves; Carvalho, Wagner Alves

    Abstract in English:

    Fixed-bed column studies were undertaken to evaluate the performance of a commercial Brazilian activated carbon in removing Pb(II) from aqueous environment. Breakthrough points were found out for the metal adsorption by varying different operating parameters like feed concentrations (10 and 20 mg L-1) and bed heights (0.5, 1.5 and 2.8 cm). A good agreement was observed between the experimental data and the values predicted by the bed depth service time (BDST) model. Regeneration of the exhausted columns was possible with HCl, and the adsorption capacity was maintained after three adsorption-desorption cycles.
  • Comparison of esters determination techniques in cachaça Artigo

    Nascimento, Eduardo S. P.; Cardoso, Daniel R.; Franco, Douglas W.

    Abstract in English:

    An analytical comparison of three different techniques for quantitative profile of esters in cachaça is reported. The Ministério da Agricultura Pecuária e Abastecimento (MAPA) recommends the use of GC/FID or volumetry. Despite being laborious and lacking in chemical speciation, the volumetric technique for total ester content shows to be appropriate, reproducible, and accurate for the analysis of cachaça. However, the GC/FID suggested by MAPA, considering only ethyl acetate, shows inaccuracy, underestimating the total ester content by a median factor of 72%, mainly due to the absence of ethyl lactate analysis. On the other hand, the GC/MS technique that comprises the analysis and speciation of nine esters, including ethyl lactate, proved to be reproducible, simple, fast and accurate for the analysis of total ester content in cachaça. Thus, the total ester content results obtained using GC/FID must be considered with precaution.
  • Application of artificial neural networks in the identification of tampered gasoline commercialized in the region of Londrina - Paraná Artigo

    Borsato, Dionísio; Moreira, Ivanira; Nobrega, Marcelo Medre; Moreira, Mariete Barbosa; Dias, Gabriel Henrique; Silva, Rui Sérgio dos Santos Ferreira da; Bona, Evandro

    Abstract in English:

    The multilayer perceptron network was used to classify the gasoline. The main parameters used in the classification were established by the Ordinance nº 309 of the Agência Nacional do Petróleo, but without informing the network the legal limits of these parameters. The network used had 10 neurons in a single hidden layer, learning rate of 0.04 and 250 training epochs. The application of artificial neural network served classify 100% of the commercialized gas in the region of Londrina-PR and to identify the tampered gasoline even those suspected of tampering.
  • Direct determination of Ca, Mg, Mn and Zn in buffalo milk of the Marajó Island by FAAS Artigo

    Pereira Junior, João B.; Fernandes, Kelly G.; Müller, Regina C. S.; Nóbrega, Joaquim A.; Palheta, Dulcidéia C.

    Abstract in English:

    This work proposes an analytical procedure for direct determination of calcium, magnesium, manganese and zinc in buffalo milk by flame atomic absorption spectrometry (FAAS). Samples were diluted with a solution containing 10% (v/v) of water-soluble tertiary amines (CFA-C) at pH 8. For comparison, buffalo milk samples were digested with HNO3 and H2O2. According to a paired t-test, the results obtained in the determination of Ca, Mg, Mn and Zn in digested samples and in 10% (v/v) CFA-C medium were in agreement at a 95% confidence level. The developed procedure is simple, rapid, decrease the possibility of contamination and can be applied for the routine determination of Ca, Mg, Mn and Zn in buffalo milk samples without any difficulty caused by matrix constituents, such as fat content, and particle size distribution in the milk emulsion.
  • Vitamin C, total phenolic compounds and antioxidant activity in guava (Psidium guajava L.) fruits from Colombia

    Rojas-Barquera, Dayana; Narváez-Cuenca, Carlos-Eduardo

    Abstract in English:

    Some physicochemical parameters, vitamin C, total phenolic compounds and antioxidant activity (AA) measured by ABTS, FRAP and DPPH methods were determinated in four different varieties of ripe guava produced in Colombia. Samples were statistically similar in their titratable acidity. Soluble solids were statistically similar and higher in "Pear", "Pink Regional", and "White Regional", but lower in "Apple" guavas. Vitamin C was statistically lower in "Pear" guava. Phenolics, ABTS-, FRAP-, and DPPH-AA were statistically lower in "Apple" guava if compared in wet basis. "Pink Regional" and "White Regional" contained the highest levels in vitamin C, phenolics and antioxidant activity.
  • Influence of basic properties of Mg,Al-mixed oxides on their catalytic activity in knoevenagel condensation between benzaldehyde and phenylsulfonylacetonitrile

    Pérez, Caridad Noda; Monteiro, José Luiz Fontes; López Nieto, Jose Manoel; Henriques, Cristiane Assumpção

    Abstract in English:

    The catalytic performance of Mg,Al-mixed oxides (MO20, MO25 and MO33) derived from hydrotalcites was evaluated in the Knoevenagel reaction between benzaldehyde and phenylsulfonylacetonitrile at 373 and 383 K. The best results were obtained for the sample MO20 that presented the highest basic sites density and external area and the smallest crystallite sizes. The relative amount of basic sites with weak to intermediate strength also played an important role on catalytic performance. By increasing the catalyst content from 1 to 5 wt.% at 383 K, a complete conversion of the reactants is attained, producing α-phenylsulfonylcinnamonitrile with a selectivity of 100%.
  • Development and validation of a GC-FID assay for determination of fluvastatin in pharmaceutical preparations

    Aslan, Serap Saglik; Ersoy, Olcay Sagirli and Lale

    Abstract in English:

    A gas chromatographic method has been developed for the assay of fluvastatin sodium (FLU). FLU was silylated with N,O-bis(trimethylsilyl)trifluoroacetamide-1% trimethylchlorosilane at 90 ºC for 30 min and analysed in a DB-1 column by capillary gas chromatograph with a flame ionization detector. The method was validated. The assay was linear over the concentration range at 10.0 to 50.0 µg mL-1. The limit of detection and the limit of quantitation were 1.0 and 3.0 µg mL-1, respectively. The recoveries of FLU derivatives were in the range of 99.25-99.80%. In inter-day and intra-day analysis, the values of relative standard deviation (%) and the relative mean error (%) were found between 0.20-0.80% and -0.20-0.75%, respectively. The developed method was succesfully applied to analyze the FLU content in tablet formulation. The results were statistically compared with those obtained by the official method, and no significant difference was found between the two methods. Therefore, it can be recommended for the quality control assay of FLU in pharmaceutical industry.
  • Phytochemical study of the wood from Guarea macrophylla (Meliaceae) Artigo

    Lago, João Henrique G.; Roque, Nídia F.

    Abstract in English:

    In the present work, the crude ethanol extract from wood of G. macrophylla was submitted to liquid/liquid partition between hexane, CH2Cl2, EtOAc and n-BuOH. Each phase was individually chromatographed over silica gel, Sephadex LH-20 or Amberlite XAD-2 to give eight terpene derivatives, such as five sesquiterpenoids (caryophyllene oxide, guai-6-en-10β-ol, spathulenol, aromadendrane-4β,10α-diol and aloaromadendrane-4α,10β-diol) as well as three triterpenoids (cicloart-24-ene-3β,23(R*)-diol, cicloart-24-ene-3β,23(S*)-diol, and cicloart-23E-ene-3β,25-diol). Additionally, were isolated three fatty acids (linolenic, linoleic and stearic), two steroids (sitosterol and stigmasterol) and sacarose. The structures of all these compounds were characterized by spectrometric analysis, mainly mass spectrometry and NMR and comparison of these data described in the literature.
  • Synthesis of chirals regioisomers from D-mannitol: obtainment of a acetylenic alcohols mixture Artigo

    Citó, Antônia Maria das Graças Lopes; Araújo, Bruno Quirino; Lopes, José Arimatéia Dantas; Magalhães, Aderbal Farias; Magalhães, Eva Gonçalves

    Abstract in English:

    The synthesis of chiral acetylenic regioisomers was described by using an appropriate intermediate such as isopropylidene glycerol, a synthon widely used in the enantioselective syntheses. This intermediate was prepared from D-mannitol. The nine obtained compounds have been characterized by their respective spectral data. The mixture of chiral acetylenic alcohols showed activity against Escherichia coli when tested through the monitoring of CO2 released during microbial respiration by using a conductimetric system.
  • Production, purification and performance improve of cyclodextrin glycosyl transferases to cyclodextrins production Artigo

    Moriwaki, Cristiane; Mazzer, Cassiana; Pazzetto, Rúbia; Matioli, Graciette

    Abstract in English:

    Biospecific affinity chromatography was used to purify three cyclodextrin glycosyl transferases (CGTases) obtained from microorganisms isolated of soil. The cyclodextrins (CDs) production by CGTases was evaluated using starches from different sources. CDs were measured through the Complexation Theory and by HPLC. CGTase from Bacillus firmus strain 7B showed the best production (30 mmol/L of β-CD and 4.3 mmol/L of γ-CD), and its cultivation conditions were optimized. The maximum enzymatic activity was achieved using lung peptone, soluble starch and agitation speed of 160 rpm. Studied CGTases were shown quite interesting for the industrial production of CDs.
  • Cd and Pb determination: evaluation of sediments from Jundiaí and Pirai streams and sludge from a wastewater treatment plant Artigo

    Souza, Silvéria Neves de Paula e; Fadini, Pedro Sérgio; Pereira-Filho, Edenir Rodrigues

    Abstract in English:

    Jundiaí river is the main stream in the Jundiaí Hydrographic Basin and its water is not considered safe for public supply. The water problem is getting worse with the development of the region. The Pirai stream, have been one of the last potable water resource. With the purpose of investigating the sediment quality, due to its influence on the water quality, bioavailable and total Cd and Pb were determined using TS-FF-AAS. Total Cd and Pb up to 2.47 and 24.7 µg g-1 were measured, respectively. The wastewater sludge showed concentrations of 4.01 and 171 µg g-1, for the same metals.
  • Chemical composition and allelophatic activity of essential oil from Hydrocotyle bonariensis Lam (araliaceae) Artigo

    Silva, Cristiane B. da; Simionatto, Euclésio; Hess, Sônia C.; Peres, Marize T. L. P.; Simionatto, Edésio L.; W. Júnior, Alberto; Poppi, Nilva R.; Faccenda, Odival; Cândido, Ana C. da Silva; Scalon, Silvana de P. Q.

    Abstract in English:

    The volatile oil obtained from the leaves of Hydrocotyle bonariensis Lam (Araliaceae) was analyzed by GC, Chiral-GC and GC-MS. It was identified 14 compounds and the monoterpene (+)-limonene (53.6%) and sesquiterpene γ-muurolene (10.5%) were the main components. The allelopathic effects of the oil were evaluated against two seeds, Lactuca sativa and Allium cepa. The results show that the oil exhibited inhibition effects in the germination and seedling growth of plants species relative to the control.
  • Volatile chemical composition of mango fruit 'Tommy Atkins', cultivated in São Francisco Valley, at different stages of maturity Artigo

    Canuto, Kirley Marques; Souza Neto, Manoel Alves de; Garruti, Deborah dos Santos

    Abstract in English:

    The effect of the maturation stages on the volatile chemical composition of mango fruit cv. Tommy Atkins, cultivated in São Francisco Valley, was investigated using SPME. GC/MS and GC-FID analysis allowed the identification of 32 compounds, consisting mainly of monoterpenes. δ-3-Carene was the major component in all the stages, while α-terpinolene, trans-β-caryophyllene e α-pinene succeded each other as the second most abundant constituent, during the ripening. The aroma of the ripe fruit was characterized by presence of short-chain ethyl esters (C2-C6), whereas the green mango contained the highest concentration of δ-3-carene. Furthermore, some terpenes were detected exclusively at one of the stages.
  • Kinetic study of the cobalt electrodeposition onto glassy carbon electrode from ammonium sulfate solutions

    Rios-Reyes, Clara Hilda; Granados-Neri, Madaí; Mendoza-Huizar, Luis Humberto

    Abstract in English:

    We carried out an electrochemical study of the cobalt electrodeposition onto glassy carbon electrode from an aqueous solution containing 10-2 M of CoSO4 + 1 M (NH4)2SO4 at natural pH 4.5. The potentiostatic study indicated a progressive 3D nucleation and growth during the deposition process. The average diffusion coefficient calculated for this system was 2.65 X 10-6 cm² s-1 while the ΔG for the formation of stable nucleus was 6.50 X 10-20 J/nuclei. The scanning electron microscopy images indicated the formation of small and homogeneous nucleus onto GCE of approximately 300 nm.
  • Synthesis of 2-iodobenzamides and 3-(iodoacetamido)benzamides linked to D-galactose and their tri-n-butyltin hydride-mediated radical carbocyclization reactions Artigo

    Leal, Daniel Henriques Soares; Queiroga, Carla Graziella; Pires, Magno Carvalho; Prado, Maria Auxiliadôra Fontes; Alves, Ricardo José; Cesar, Amary

    Abstract in English:

    Starting from methyl 6-O-allyl-4-azido-2,3-di-O-benzyl-4-deoxy-α-D-galactopyranoside, four new derivatives containing 2-iodobenzamido and 3-(iodoacetamido)benzamido groups were synthesized. These four compounds were submitted to tri-n-butyltin hydride mediated radical cyclization reactions, resulting in two macrolactams from 11- and 15-endo aryl radical cyclization. The corresponding four hydrogenolysis products were also obtained. The structures of the new compounds were elucidated by ¹H and 13C NMR spectroscopy, DEPT, COSY, HMQC and HMBC experiments.
  • Flow-injection turbidimetric determination of fluoxetine hydrochloride in pharmaceutical formulations Artigo

    Suarez, Willian Toito; Sartori, Elen Romão; Batista, Érica Ferreira; Fatibello-Filho, Orlando

    Abstract in English:

    A simple, accurate and precise flow-injection turbidimetric procedure for the determination of fluoxetine hydrochloride in pharmaceutical formulations is reported. The procedure is based on the precipitation of chloride of fluoxetine hydrochloride with silver nitrate solution and the yielded insoluble AgCl(s) was monitored at 420 nm. The analytical curve was linear in the fluoxetine hydrochloride concentration range 3.0 x 10-5 - 5.0 x 10-4 mol L-1 with a detection limit of 10 µmol L-1 and, a sample throughout of 60 h-1.
  • Determination of ethanol and related volatile compounds in blood and oral fluid by headspace solid-phase micro extraction associated to gas chromatography with flame-ionization detector Artigo

    Feltraco, Lílian de Lima; Antunes, Marina Venzon; Linden, Rafael

    Abstract in English:

    The aim of this study was to validate a method for the determination of acethaldehyde, methanol, ethanol, acetone and isopropanol employing solid-phase microextraction associated to gas chromatography with flame ionization detection. The operational conditions of SPME were optimized by response surface analysis. The calibration curves for all compounds were linear with r² > 0.9973. Accuracy (89.1-109.0%), intra-assay precision (1.8-8.5%) and inter-assay precision (2.2-8.2%) were acceptable. The quantification limit was 50 µg/mL. The method was applied to the meaurement of ethanol in blood and oral fluid of a group of volunteers. Oral fluid ethanol concentrations were not directly correlated with blood concentrations.
  • Energy dispersive X-ray fluorescence applied to mapping of tree stems in Campinas, São Paulo Artigo

    Col, José Augusto da; Bueno, Maria Izabel Maretti Silveira

    Abstract in English:

    Dendrochemistry is based on the determination of elements retained in tree rings, which can be useful to characterize environmental occurrences. This work shows elemental mappings obtained by EDXRF of the cross section of a tree stem. The tree is originated from a polluted area in Campinas, São Paulo. Some profiles, as the sulfur one, show variations that can be attributed to external contributions, whereas the silicon one can be inferred to a protection defense natural mechanism. Besides being simultaneous and multielementar, the main advantages here are its performance through a non-destructive sample treatment and the ease of operation of XRF equipments.
  • Construction and characterization of an electrochemical detector for flow analysis Artigo

    Santos, Wallans Torres P. dos; Azevedo, Eduardo F.; Richter, Eduardo M.; Albuquerque, Yaico D. Tanimoto de

    Abstract in English:

    The present work describes a low-cost electrochemical "wall-jet" detector for flow analysis. The electrolytic solution enters into the cell through a tube of stainless steel (200 to 300 µm i.d), reaching to the center of the working electrode perpendicularly and then being mixed to the remaining solution in the cell, which flows under atmospheric pressure into a waste reservoir. The proposed electrochemical detector can be used with any type of working electrode, from commercial to home-made, such as glassy carbon and metallic electrodes (modified or unmodified), which enlarge the applications of the electrochemical detector.
  • Oxidative demage in the microalgae Pseudokirchneriella subcapitata exposed to receiving waters of a mining effluent in the Rio Blanco (V Region, Chile)

    Aránguiz, Fernanda; Gaete, Hernán; Hidalgo, María Eliana; Lobos, Gabriela

    Abstract in English:

    In this investigation antioxidant response and toxicity of metals in receiving water effluent miner in the Blanco river in Pseudokirchneriella subcapitata was assessed. The catalase activity, lipid damage through Tbars, the growth rate of was determined. The result showed an inhibition of the growth rate of P. subcapitata which correlated with increased catalase activity and the lipid liperoxidation. These responses were correlated with the concentrations of copper and iron.
  • A heterogeneous photocatalysis study of decolorization of synthetic dyes on Ti/TiO Artigo

    Cervantes, Thiago N. M.; Zaia, Dimas A. M.; Santana, Henrique de

    Abstract in English:

    The main goal of this paper was to study the degradation of synthetic dyes using photoelectrocatalytic properties of particulate films of TiO2 supported on plates of titanium and stimulated by UV-Vis radiation. The dyes decolorizations were measured using spectrophotometric methods to verify which the conditions on Ti/TiO2 electrode was the best for the photoelectrodegradation of them. The results showed that decolorization rates were higher than 90% during a period of 270 min. FT-IR spectroscopy showed that intermediate substances were formed after the decolorization and N=N group/aromatic structures were preserved independently of the specific structure of the dyes.
  • Carotenoids production: microorganisms as source of natural dyes

    Valduga, Eunice; Tatsch, Pihetra Oliveira; Tiggemann, Lídia; Treichel, Helen; Toniazzo, Geciane; Zeni, Jamile; Di Luccio, Marco; Fúrigo Júnior, Agenor

    Abstract in English:

    Carotenoids are natural dyes synthesized by plants, algae and microorganisms. Application in many sectors can be found, as food dyeing and supplementation, pharmaceuticals, cosmetics and animal feed. Recent investigations have shown their ability to reduce the risks for many degenerative diseases like cancer, heart diseases, cataract and macular degeneration. An advantage of microbial carotenoids is the fact that the cultivation in controlled conditions is not dependent of climate, season or soil composition. In this review the advances in bio-production of carotenoids are presented, discussing the main factors that influence the microbial production of these dyes in different systems.
  • The benzyne chemistry revival with silylaryl triflates in the context of insertion reactions into sigma bonds Revisão

    Gallo, Rafael D. C.; Rezende, Hellenicy V.; Muzzi, Rozanna M.; Raminelli, Cristiano

    Abstract in English:

    In this paper we gathered articles concerning insertion reactions of arynes, exclusively generated from 2-(trimethylsilyl)aryl triflates in the presence of fluoride ions, in substrates bearing nucleophilic and electrophilic portions separated by sigma bonds. Accordingly, we stand out the great importance and versatility of such transformations in the preparation of highly functionalized aromatic systems, which are hardly synthesized in just one step for other methods.
  • Chemotherapy of Chagas' disease: state of the art and perspectives for the development of new drugs Revisão

    Dias, Luiz C.; Dessoy, Marco A.; Silva, Jean Jerley N.; Thiemann, Otavio H.; Oliva, Glaucius; Andricopulo, Adriano D.

    Abstract in English:

    Neglected diseases are a major global cause of illness, long-term disability and death. Chagas' disease is a parasitic infection widely distributed throughout Latin America, with devastating consequences in terms of human morbidity and mortality. The existing drug therapy suffers from a combination of drawbacks including poor efficacy, resistance and serious side effects. In 2009, we celebrate the 100th anniversary of the discovery of Chagas' disease, facing the challenges of developing new, safe and effective drugs for the treatment of this disease. This brief review attempts to highlight the state of the art, limitations and perspectives of Chagas' disease drug development.
  • Spectrophotometric determination of hexamethylenetetramine (HMT) in pharmaceutical preparations using chromotropic acid and microwave oven Nota Técnica

    Fagnani, Enelton; Pezza, Leonardo; Pezza, Helena Redigolo

    Abstract in English:

    This paper proposes a methodology for spectrophotometric determination of hexamethylenetetramine (HMT) by using chromotropic acid in a phosphoric acid media employing a domestic microwave oven as a source of heating. The reddish-purple soluble product is quantitatively formed after 30 s of irradiation and obeys the Beer´s law in the range between 0.1-1.2 mg L-1 HMT (r = 0.99925). The method was applied successfully in commercial pharmaceutical preparations containing dyes in their composition. The results showed that the method proposed is feasible for simplicity, speed, low cost, precision and accuracy when compared with United States Pharmacopeia official method.
  • Evaluation of the influence of base and alkyl bromide on synthesis of pyrazinoic acid esters through fatorial design

    Fernandes, João Paulo dos Santos; Felli, Veni Maria Andres

    Abstract in English:

    Pyrazinoic acid esters have been synthesized as prodrugs of pyrazinoic acid. In the literature, its preparation is reported through the reaction of pyrazinoyl chloride with alcohols and the reaction with DCC/DMAP. In this work, it is reported a 2² factorial design to evaluate the preparation of these esters through the substitution of alkyl bromides with carboxylate anion. The controlled factors were alkyl chain length of bromides (ethyl and hexyl) and the used base (triethylamine and DBU). Results revealed that the used base used has significant effect on yield, and alkyl bromide used has neither significant influence, nor its interaction effect with base.
  • Comparative study of the ozonation of genetically modified and not modified sunflower oils

    Díaz Gómez, Maritza F.; Ledea Lozano, Oscar E.; Gómez Regüeiferio, Magali; Garcés Mancheño, Rafael; Alaiz Barragán, Manuel S.; Martínez Force, Enrique

    Abstract in English:

    Ozonation of sunflower oils with genetic modification High Oleic and High Oleic-Palmitic (AO and PO respectively) and without modification, High Linoleic (AL) at different applied ozone dosages was carried out with measurement of peroxide and acidity indexes values, fatty acids composition, oxygen percentage content and antimicrobial activity. The comparison of peroxides indexes and oxygen content at different applied ozone dosages in each oil showed good correlation (r = 0,99). Higher amount of oleic acid was consumed at higher applied ozone dosage in PO oil than AO oil, which can be related to the increase of acidity index. The antimicrobial activity was better for AL and PO ozonized oils.
  • An expeditious and consistent procedure for tetrahydrofuran (THF) drying and deoxygenation by the still apparatus

    Simas, Alessandro B. C.; Pereira, Vera L. P.; Barreto Jr., Cleber B.; Sales, Daniel L. de; Carvalho, Leandro L. de

    Abstract in English:

    Despite the availability of alternative methods for drying tetrahydrofuran (THF), the use of the still apparatus, wherein a THF solution containing Na-bezophenone ketyl is heated to reflux, remains widespread. We herein propose a set of procedures to solve the problems usually faced in applying this drying technique. Moreover, a discussion is made on the chemical knowledge underlying such procedures. Safety and economy issues concerned with the operation of the THF still apparatus are also discussed.
  • Validation of chromatographic methods: an experiment using HPLC and Green Chemistry in methylxanthines determination Educação

    Aragão, Nádia Machado de; Veloso, Márcia Cristina da Cunha; Andrade, Jailson Bittencourt de

    Abstract in English:

    The validation of analytical methods is an important step in quality control. The main objective of this study is to propose an HPLC experiment to verify the parameters of validation of chromatographic methods, based on green chemistry principles, which can be used in experimental courses of chemistry and related areas.
  • The role of acidity and organic modifiers in the methylxanthines determination: a HPLC experiment Educação

    Aragão, Nádia Machado de; Veloso, Márcia Cristina da Cunha; Bispo, Marcia Sousa; Andrade, Jailson Bittencourt de

    Abstract in English:

    In this work a new experiment using HPLC is proposed in order to explore the role of acidity and the organic modifiers in the determination of methylxanthines in tea and coffee. Multivariate and univariate optimizations of the experimental conditions were used.
  • Quantum Chemistry Models in the momentum space: different representations of the same system Educação

    Hermoso, Willian; Ornellas, Fernando R.

    Abstract in English:

    The conventional approach to simple quantum chemistry models is contrasted with that known as momentum representation, where the wavefunctions are momentum dependent. Since the physical interactions are the same, state energies should not change, and whence the energy differences correlating with the real world as spectral lines or bands. We emphasize that one representation is not more fundamental than the other, and the choice is a matter of mathematical convenience. As spatial localization is rooted in our brains, to think in terms of the momentum present us a great mental challenge that can lead to complementary perspectives of a model.
  • The luso-brazilian chemist and naturalist Alexandre Antonio Vandelli Assuntos Gerais

    Marques, Adílio Jorge; Filgueiras, Carlos A. L.

    Abstract in English:

    Alexandre Vandelli was the heir of two illustrious scientific traditions in the Luso-Brazilian world of the late eighteenth and early nineteenth centuries, that of his father, the celebrated Italian-Portuguese naturalist and chemist Domingos (Domenico) Vandelli, and that of his father-in-law, that protean figure in several scientific specialties as well as in politics, José Bonifácio de Andrada e Silva, who in later life was of paramount importance in the process of Brazilian independence from Portugal. The younger Vandelli followed their footsteps but soon engaged in a multiple career, at first in Portugal and later in Brazil, of which little is known and is here presented for the first time.
  • Natural hallucinogens: a flight from Medieval Europe to Brazil Assuntos Gerais

    Martinez, Sabrina T.; Almeida, Márcia R.; Pinto, Angelo C.

    Abstract in English:

    This work describes the historical importance and the use of hallucinogenic plants by different civilizations. A comparison between three Brazilian plants whose active principle is N,N-dimethyltriptamine (DMT), and three plant species native to Europe whose active principles are tropanic alkaloids was carried out and we observed these plants promoted different types of hallucinations.
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