RESUMO
Decomplexation of organic ligands through redox titration has been applied to catalyst synthesis, developing an improved preparation method for Fe-ferrierite (Fe-FER), the catalyst showing excellent performance and durability for N2O decomposition under realistic conditions for nitric acid plants.
RESUMO
It is demonstrated that biological species like limpets can be classified according to their level of n-alkanes when artificial neural networks are applied. Marine intertidal and subtidal limpets of the Canary Islands (Spain), Patella piperata, Patella candei crenata and Patella ulyssiponensis aspera were selected as bioindicator organisms. Samples were collected at four stations on the coasts of Fuerteventura. Concentration of n-alkanes in the soft tissues of the limpets has been determined by gas chromatography. Data were treated with artificial neural networks (ANNs) and it was found that using suitable architecture of a supervised artificial neural network, the limpets can be successfully distinguished (classified) up to 98%.
Assuntos
Alcanos/metabolismo , Moluscos/classificação , Moluscos/metabolismo , Redes Neurais de Computação , Alcanos/química , Animais , Biomarcadores/análise , Cromatografia Gasosa , Poluentes Químicos da Água/análiseRESUMO
Phenolic compounds including phenolic aldehydes, acids and flavonoids are separated by high-performance liquid chromatography (HPLC) with analysis time shorter than described in the literature. The use of a fluorescence detector in series with absorbance detector allowed increasing selectivity and sensitivity for the determination of catechin, vanillic acid, syringic acid, epicatechin and trans-resveratrol in wine samples. An optimised sample preparation method using liquid-liquid extraction with diethyl ether at pH 2.0 was used. The optimised method was applied to analyse wine samples with good results.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Fenóis/isolamento & purificação , Calibragem , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrometria de Fluorescência , Espectrofotometria UltravioletaRESUMO
Chemical fingerprinting approach to environmental assessment is illustrated in the evaluation of marine oil pollution in the coasts using two limpet species as bioindicator organisms, and based on profiles and concentrations of n-alkanes and aromatic hydrocarbons in their tissues. Accidental and chronic releases of hydrocarbons can contaminate the marine environment of the Canary Islands not only because of their geographical situation but also because of the very dense tanker traffic around. This situation affects coastal areas, fishing activities, tourism resort, etc. Concentrations of n-alkanes and aromatic hydrocarbons (polycyclic aromatic hydrocarbons and methyl-polycyclic aromatic hydrocarbons) in the soft tissues of the marine intertidal and subtidal limpets, Patella crenata and Patella ullysiponensis aspera, were evaluated. Limpet samples were collected at monthly intervals, at three locations on the southeast coast of Tenerife over a 3-year period (1991-93). Levels of hydrocarbons found in limpets are similar to concentrations found in unpolluted areas around the world. From application of principal component analysis, the interpretation of variable loading plots gives information on variable correlation and can be used to distinguish among potential sources of pollution and the ability of studied molluscs to be used as bioindicator organisms.
Assuntos
Monitoramento Ambiental/métodos , Moluscos/química , Petróleo/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Alcanos/análise , Animais , Biomarcadores , Hidrocarbonetos Policíclicos Aromáticos/farmacocinética , Espanha , Distribuição TecidualRESUMO
A group of phenolic compounds including phenolic aldehydes, acids and flavonoids are separated by micellar electrokinetic chromatography (MECC). The influence of buffer (concentration and pH), concentration of sodium dodecylsulphate (SDS) and applied voltage were studied. To increase the selectivity of the separation and the resolution of the solutes organic solvents are added to the separation buffer, the best results were obtained when methanol was used at lower percentages. An optimized buffer (150 mM boric acid (pH 8.5)-50 mM SDS-5% methanol) provides the optimum separation with regard to resolution and migration time. This method was applied to the determination of these compounds in wine samples with good results.
Assuntos
Cromatografia Capilar Eletrocinética Micelar/métodos , Fenóis/isolamento & purificação , Soluções Tampão , Eletrólitos , Vinho/análiseAssuntos
Alcanos/metabolismo , Moluscos/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Água do Mar , Poluentes Químicos da Água/metabolismo , Poluição Química da Água , Alcanos/análise , Animais , Cromatografia Gasosa , Monitoramento Ambiental , Resíduos Industriais , Moluscos/química , Petróleo , Hidrocarbonetos Policíclicos Aromáticos/análise , Espanha , Poluentes Químicos da Água/análise , Poluição Química da Água/análiseRESUMO
The hydrocarbons contents (n-alkanes, polycyclic aromatic hydrocarbons) were determined in the sea urchin Arbacia lixula. Multivariate data analysis as principal component analysis, factor analysis and, cluster analysis were applied to elucidate sources of pollution. PCA and FA were performed to establish the relationships between variables (hydrocarbons), samples (sea urchin) and sources of pollution.