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Search Results: 1 - 10 of 586270 matches for " Débora A. Azevedo "
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A preliminary investigation of the polar lipids in recent tropical sediments from aquatic environments at Campos dos Goytacazes, Brazil
Azevedo, Débora de A.;
Journal of the Brazilian Chemical Society , 2003, DOI: 10.1590/S0103-50532003000100016
Abstract: the polar fractions extracted from sediments of the imbé, urubu, and ururaí rivers and from lake de cima were analyzed using gas chromatography and gas chromatography-mass spectrometry. in the samples, cholest-5-en-3b-ol, 24-methylcholest-5-en-3b-ol, 24-ethylcholest-5-en-3b-ol, 24-ethylcholesta-5,22-dien-3b-ol and their 5a-counterparts were dominant among the sterols. sediments of theses water bodies have the c29 sterols as the most abundant, emphasizing a higher plant input. in the ururaí river, cholest-5-en-3b-ol predominated, reflecting a major algal contribution. olean-12-en-3b-ol (b-amyrin) and friedelan-3-one were prevalent among the triterpenoids in the imbé and the urubu sediments, but were not detected at lake de cima. samples of the imbé and urubu rivers contained appreciable concentrations of n-alkanols. they ranged from c14 to c32 with a maximum at c16 and with a second maximum in c28. results of all four sediments point to a mixed contribution of higher plants and algae/zooplankton. alkanols found in these water bodies indicate a greater contribution of higher plant material, while in sediments from the ururaí algae/zooplankton were the main sources of the organic matter.
A preliminary investigation of the polar lipids in recent tropical sediments from aquatic environments at Campos dos Goytacazes, Brazil
Azevedo Débora de A.
Journal of the Brazilian Chemical Society , 2003,
Abstract: The polar fractions extracted from sediments of the Imbé, Urubu, and Ururaí rivers and from Lake de Cima were analyzed using gas chromatography and gas chromatography-mass spectrometry. In the samples, cholest-5-en-3beta-ol, 24-methylcholest-5-en-3beta-ol, 24-ethylcholest-5-en-3beta-ol, 24-ethylcholesta-5,22-dien-3beta-ol and their 5alpha-counterparts were dominant among the sterols. Sediments of theses water bodies have the C29 sterols as the most abundant, emphasizing a higher plant input. In the Ururaí River, cholest-5-en-3beta-ol predominated, reflecting a major algal contribution. Olean-12-en-3beta-ol (beta-amyrin) and friedelan-3-one were prevalent among the triterpenoids in the Imbé and the Urubu sediments, but were not detected at Lake de Cima. Samples of the Imbé and Urubu rivers contained appreciable concentrations of n-alkanols. They ranged from C14 to C32 with a maximum at C16 and with a second maximum in C28. Results of all four sediments point to a mixed contribution of higher plants and algae/zooplankton. Alkanols found in these water bodies indicate a greater contribution of higher plant material, while in sediments from the Ururaí algae/zooplankton were the main sources of the organic matter.
Aliphatic and aromatic hydrocarbons in tropical recent sediments of Campos dos Goytacazes, RJ, Brazil
Gomes, Alexandre de O.;Azevedo, Débora de A.;
Journal of the Brazilian Chemical Society , 2003, DOI: 10.1590/S0103-50532003000300004
Abstract: sediment samples from the imbé, the urubu and the ururaí rivers and from lake de cima were studied. these sites are located in the county of campos dos goytacazes, rio de janeiro, brazil. aliphatic and aromatic fractions were analyzed by gc-fid and gc-ms in order to gather information on the degree of contamination by anthropogenic activities and other biogenic contributions. concentrations of total aliphatic and aromatic hydrocarbons were 1.2, 2.8, 5.8 and 4.3 mg g-1 and 74, 30, 722 and 340 ng g-1 in the imbé, ururaí, urubu rivers and lake de cima, respectively. the c20 highly branched isoprenoid alkane was identified in the urubu sediment. there were no hopanes or steranes in any sample. anthropogenic aromatic compounds, detected at trace levels, were observed only in the imbé and in lake de cima (227 ng g-1). the fluoranthene/pyrene rate for lake de cima was 4.2, suggesting a combustion origin for the pah. this data is consistent with the frequently sugar cane burning practice that occurs in this region. a greater input from higher plants was observed in the urubu, imbé and lake de cima sediments; on the other hand, the aquatic input predominates for ururaí. in summary, lake de cima sediment is considered very slightly polluted, while the others are unpolluted.
Aliphatic and aromatic hydrocarbons in tropical recent sediments of Campos dos Goytacazes, RJ, Brazil
Gomes Alexandre de O.,Azevedo Débora de A.
Journal of the Brazilian Chemical Society , 2003,
Abstract: Sediment samples from the Imbé, the Urubu and the Ururaí rivers and from Lake de Cima were studied. These sites are located in the county of Campos dos Goytacazes, Rio de Janeiro, Brazil. Aliphatic and aromatic fractions were analyzed by GC-FID and GC-MS in order to gather information on the degree of contamination by anthropogenic activities and other biogenic contributions. Concentrations of total aliphatic and aromatic hydrocarbons were 1.2, 2.8, 5.8 and 4.3 mug g-1 and 74, 30, 722 and 340 ng g-1 in the Imbé, Ururaí, Urubu rivers and Lake de Cima, respectively. The C20 highly branched isoprenoid alkane was identified in the Urubu sediment. There were no hopanes or steranes in any sample. Anthropogenic aromatic compounds, detected at trace levels, were observed only in the Imbé and in Lake de Cima (227 ng g-1). The fluoranthene/pyrene rate for Lake de Cima was 4.2, suggesting a combustion origin for the PAH. This data is consistent with the frequently sugar cane burning practice that occurs in this region. A greater input from higher plants was observed in the Urubu, Imbé and Lake de Cima sediments; on the other hand, the aquatic input predominates for Ururaí. In summary, Lake de Cima sediment is considered very slightly polluted, while the others are unpolluted.
Brazilian gasoline quality: study of adulteration by statistical analysis and gas chromatography
Wiedemann, Larissa S. M.;d'Avila, Luiz A.;Azevedo, Débora de A.;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000200003
Abstract: the addition of organic solvents (heavy aliphatic, light aliphatic and aromatic hydrocarbons) in brazilian gasoline is unfortunately very frequent, and this illicit practice does not guarantee gasoline quality. organic solvent adulterations of gasoline samples have been investigated. for characterization and comparison of these samples, physico-chemical parameters were selected as the factor for hierarchic multivariate analysis (cluster analysis). however, these parameters are not efficient to detected all kinds of adulteration. gas chromatographic (gc) analysis can be used as a procedure to improve the detection of adulterated gasoline. more detailed information of their compositions was revealed. the use of physico-chemical properties of gasoline samples for hierarchic multivariate analysis and gas chromatographic fingerprints is a practicable method to adulteration detection.
Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from two Brazilian estuarine systems
Maioli, Otávio L. G.;Rodrigues, Kamila C.;Knoppers, Bastiaan A.;Azevedo, Débora A.;
Journal of the Brazilian Chemical Society , 2010, DOI: 10.1590/S0103-50532010000800020
Abstract: this study focuses on the tropical estuarine systems of mundaú-manguaba (mmels) and paraíba do sul river (psr), brazil, affected by sugarcane monoculture practices and also urbanization. the levels of 17 polycyclic aromatic hydrocarbons (pahs), 16 of which are classified as priority pollutants by the us-epa and perylene (a biogenic pah) were measured in surface sediments to identify pollution sources and determine baseline data looking for future management strategies. the σ16pah ranged from 2.90 to 231.30 μg kg-1 in mmels and from 87.10 to 9344.29 μg kg-1 in the psr. pah isomeric ratios suggested mainly pyrogenic input.
Triazines in the tropical lagoon system of Mundaú-Manguaba, NE-Brazil
Azevedo, Débora A.;Silva, Thaís R.;Knoppers, Bastiaan A.;Schulz-Bull, Detlef;
Journal of the Brazilian Chemical Society , 2010, DOI: 10.1590/S0103-50532010000600020
Abstract: this study addresses triazines in the tropical and eutrophic mundaú-manguaba estuarine-lagoon system (mmels) located in the state of alagoas, ne-brazil, affected by sugar-cane monoculture in its lower drainage basin. water and sediment samples from mmels were collected during the wet post-harvest season (august/2006) and the dry harvest season (february/2008). trace analysis of the triazines atrazine, simazine, deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine were performed in surface sediments, suspended particulate matter and in the dissolved fraction in water. water samples were filtered and after the analytical procedures, the resulting extracts were analyzed by gas chromatography-mass spectrometry. additionally, the analytical method for suspended particulate matter was evaluated, the recovery being between 72-123 % with relative standard deviations of 4.2-22 % and limits of detection around 0.2-0.3 ng l-1. sediments fortified at 10, 20 and 50 ng g-1 were extracted with the ase system and recovery experiments lied between 68-133 % with relative standard deviations of 2-34 %. the limits of detection were of 0.6-1.2 ng g-1. atrazine was the sole triazine detected and only in suspended particulate matter during the wet season at four sites, with low concentrations of 3.1, 2.7, 1.6 and 0.7 ng l-1. this suggests that triazines are either largely retained and transformed within the sugar-cane fields and/or are readily diluted in the waters and degraded due to the intense metabolism of mmels.
Chemotaxonomical aspects of lower Cretaceous amber from Rec?ncavo Basin, Brazil
Pereira, Ricardo;Carvalho, Ismar S.;Fernandes, Antonio Carlos S.;Azevedo, Débora A.;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000800015
Abstract: the chemical composition of lower cretaceous amber samples from rec?ncavo basin (salvador, bahia) was performed by gc-ms to characterize possible botanical sources. the compounds identified were hydrocarbonic and polar diterpenoids, such as abietane, dehydroabietane, tetrahydroretene, dehydroabietol, dehydroabietic acid, ferruginol and sugiol. other diterpenoid classes were not detected as well as triterpenoids. the composition of the extracts and chemosystematic data allows relating the samples to conifers of podocarpaceae or cheirolepidiaceae families due to detection of ferruginol, a specific biomarker to these families. the data concerning cretaceous amber in the rec?ncavo basin provided information concerning the presence of a resinous flora in the maracangalha formation sediments during the lower cretaceous.
Occurrence of nonylphenol and bisphenol-A in surface waters from Portugal
Azevedo, Débora de A.;Lacorte, Silvia;Viana, Paula;Barceló, Damià;
Journal of the Brazilian Chemical Society , 2001, DOI: 10.1590/S0103-50532001000400015
Abstract: the occurrence of the endocrine disruptor compounds, such as 4-nonylphenol isomers and bisphenol a was determined in surface water samples from portugal. the analytical method used involved the preconcentration of 200 ml of water sample by solid phase extraction (spe) using a oasis (waters) cartridge, followed by gas chromatography-mass spectrometry (gc/ms) determination. recoveries and limits of detection of 4-nonylphenol isomers and bisphenol-a were 73 % and 119 %, respectively, 0.01 mg l-1 and 0.002 mg l-1. the method was applied to the determination of these estrogenic pollutants in river and coastal waters during three months (august-october/1999). the total samples analyzed were 135. concentrations of 4-nonylphenol isomers and bisphenol-a ranged from 0.03-30 mg l-1 and 0.07-4.0 mg l-1, respectively. only in two river samples, concentrations of 4-nonylphenol isomers were above 10 mg l-1 and bisphenol-a were above 2 mg l-1. these values can cause estrogenic effects in fish and these sampling points require further investigation in order to verify the maintenance of these levels.
Monitoring of pesticides and polycyclic aromatic hydrocarbons in water from Paraíba do Sul River, Brazil
Azevedo, Débora de A.;Gerchon, Elaine;Reis, Ederson O. dos;
Journal of the Brazilian Chemical Society , 2004, DOI: 10.1590/S0103-50532004000200021
Abstract: the paraíba do sul river, in the state of rio de janeiro, was studied for its water quality, by determining the levels of selected polycyclic aromatic hydrocarbons (pahs) and pesticides from six sites in two cities, resende and campos dos goytacazes, as they have industrial and agricultural activities. this study was carried out between july 2001 and march 2002. the method involved 200 ml samples taken by off-line, solid phase extraction by oasis polymeric cartridges followed by gas chromatography-mass spectrometry (gc-ms). recoveries and standard deviation of pesticides in non polluted real water sample spiked with a standard mixture were 82-119% and less then 20%. for pah, recoveries and standard deviation were 56-78% and less then 18%, respectively, with exception to acenaphthylene, 23% and 2.7%. atrazine was detected in the average concentration of 0.231 μg l-1 in two sites in campos dos goytacazes, near the sugar-cane power plants and plantations area, while no detection was observed in resende. irgarol was observed in campos dos goytacazes downtown at 0.138 μg l-1, an area of small boating activities. benzo[a]pyrene was detected at 0.255 μg l-1 in resende, near the presidente dutra highway. pahs were not detected in the water samples from campos dos goytacazes.
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