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Recebido em 4/9/08; aceito em 13/5/09; publicado na web em 6/11/09 VALIDATION OF CHROMATOGRAPHIC METHODS-AN EXPERIMENT USING HPLC AND GREEN CHEMISTRY IN METHYLXANTHINES DETERMINATION. 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.

Contamination at Todos os Santos BayAbstract: Todos os Santos Bay (BTS) is the second largest coastal bay in Brazil, which occupies an area of 1,233 km 2 and 184 km of coastline perimeter. The BTS includes an urban area, including Salvador, with more than 3 million inhabitants and an extensive industrial area. This paper focuses on the chemical contamination of the atmosphere and marine coastal system of BTS, discussing the main sources of different compounds found. In several regions of the BTS atmospheric particulate matter, suspended particulate matter, algae, sediment and biota are enriched with trace elements (As, Cd, Pb, Zn, Hg, Mn, Co, Cu, Sb, among others) and organic contaminants (PAH and n-alkanes) at concentration levels above those considered "natural". Therefore, anthropogenic contributions (industrial discharges and domestic oil and gas extraction, power generation processes, vehicular emission and port activities) contributed to the environmental levels of contaminants studied to date. Keywords:Contaminants; metals; hydrocarbons; atmosphere; sediments; biota; Todos os Santos Bay. ResumoA Baía de Todos os Santos (BTS) é a segunda maior baía costeira do Brasil, em que ocupa uma área de 1.233 km 2 e 184 km de perímetro de costa. O entorno da BTS compreende uma área urbana, incluindo Salvador, com mais de 3 milhões de habitantes e uma extensa zona industrial. O foco deste trabalho está sobre a contaminação química da atmosfera e do sistema costeiro marinho da BTS, discutindo as principais fontes de diferentes compostos encontrados. Em várias regiões da BTS o material particulado atmosférico, material particulado em suspensão, sedimentos e biota encontram-se enriquecidos por elementos traço (As, Cd, Pb, Zn, Hg, Mn, Co, Cu, Sb, dentre outros) e por contaminantes orgânicos (nalcanos e HPA) em níveis de concentração acima do co siderado atural . Logo, as o tri uições antrópicas (descargas de efluentes industriais e domésticos, extração de petróleo e gás, processos de geração de energia, emissão veicular e atividades portuárias) contribuíram para os níveis ambientais dos contaminantes estudados até o presente momento.

In this work, multivariate optimization techniques were used to develop a method based on the ultrasoundassisted extraction for copper, manganese, nickel and zinc determination from rations for chicken nutrition using flame atomic absorption spectrometry. The proportions of extracting components (2.0 mol.L -1 nitric, hydrochloric and acetic acid solutions) were optimized using centroid-simplex mixture design. The optimum proportions of this mixture taken as percentage of each component were respectively 20%, 37% and 43%. variables of method (sample mass, sonication time and final acid concentration) were optimized using Doehlert design. The optimum values found for these variables were respectively 0.24 g, 18s and 3.6 mol.L -1 . The developed method allows copper, manganese, nickel and zinc determination with quantification limits of 2.82; 4.52; 10.7; e 9.69 µg.g -1, and precision expressed as relative standard deviation (%RSd, 25 µg.g -1 , N = 5) of 5.30; 2.13; 0.88; and 0.83%, respectively. This method was applied in the analytes determination from chicken rations collected from specialized commerce in Jequié city (Bahia State/Brazil). Application of paired t-test at the obtained results, in a confidence level of 95%, does not show significant difference between the proposed method and the microwave-assisted digestion.

The methanolic extract from stem bark of Bauhinia monandra, a medicinal plant employed in folk medicine, yielded by column chromatography lup-20(29)-en-3β,24-diol (1) and methyl galloate (2) along with β-sitosterol (3). These known phytoconstituents are being reported for the first time from this plant and their structures were established by NMR and MS spectral studies and by comparison with their literature data. Furthermore, lup-20(29)-en-3β,24-diol (1), a minor constituent, was isolated from this genus for the first time.