In this work, an alternative procedure for the determination of As in vegetable oils and biodiesel of different origins by graphite furnace atomic absorption spectrometry (GFAAS) is proposed. The sample stabilization was achieved by the formation of three component solutions prepared mixing the samples with appropriate volumes of propan-1-ol and nitric acid. Palladium was used as a chemical modifier. Pyrolysis and atomization temperatures as well as the sample dilution factor were investigated and optimized. Because no adequate certified reference material was available, accuracy was assessed by recovery tests, using both organic and inorganic species. Recoveries ranged from 95 to 110%. The limit of detection in the original sample was 0.3 mg kg−1, which is adequate for the analysis of vegetable oils and biodiesel, according to the expected Brazilian legislation.

The antibacterial activity and efflux pump reversal of thymol and carvacrol were investigated against the Staphylococcus aureus IS-58 strain in this study, as well as their toxicity against Drosophila melanogaster. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method, while efflux pump inhibition was assessed by reduction of the antibiotic and ethidium bromide (EtBr) MICs. D. melanogaster toxicity was tested using the fumigation method. Both thymol and carvacrol presented antibacterial activities with MICs of 72 and 256 µg/mL, respectively. The association between thymol and tetracycline demonstrated synergism, while the association between carvacrol and tetracycline presented antagonism. The compound and EtBr combinations did not differ from controls. Thymol and carvacrol toxicity against D. melanogaster were evidenced with EC50 values of 17.96 and 16.97 µg/mL, respectively, with 48 h of exposure. In conclusion, the compounds presented promising antibacterial activity against the tested strain, although no efficacy was observed in terms of efflux pump inhibition.

: The Aedes aegypti is responsible for the transmission of arboviruses, which compromise public health. In the search for synthetic product alternatives, essential oils (OEs) have been highlighted by many researchers as natural insecticides. This systematic review (SR) was performed according to PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and had as it’s objective to evaluate studies addressing OEs with larvicidal properties against Ae. aegypti, through electronic database searches (Pubmed, Science Direct and Scielo), covering an overview of the plant sources OEs, which plant parts were used, the extraction methods, analytical techniques, major and/or secondary constituents with greater percentages, as well as the LC50s responsible for larval mortality. Following study analysis, plants distributed across 32 families, 90 genera and 175 species were identified. The Lamiaceae, Myrtaceae, Piperaceae, Asteraceae, Rutaceae, Euphorbiaceae and Lauraceae families obtained the highest number of species with toxic properties against larvae from this vector. Practically all plant parts were found to be used for OE extraction. Hydrodistillation and steam distillation were the main extraction methods identified, with GC-MS/GC-FID representing the main analytical techniques used to reveal their chemical composition, especially of terpene compounds. In this context, OEs are promising alternatives for the investigation of natural, ecologically correct and biodegradable insecticides with the potential to be used in Ae. aegypti control programs.

Recentemente, a Associação Brasileira de Normas Técnicas (ABNT) lançou uma série de normas, relacionadas com a determinação de Na, K, Mg e Ca em biodiesel, recomendando procedimentos similares àqueles das normas europeias e americanas, mas também introduzindo uma norma alternativa (ABNT NBR 15556), que possibilita a determinação dos 4 elementos usando a técnica de espectrometria de absorção atômica com chama (F AAS). Neste trabalho, apresentam-se os estudos de otimização e validação que dão suporte a essa norma, bem como a comparação do desempenho de um equipamento com fonte de linhas com outro de fonte contínua. Entre os fatores otimizados, os baixos valores de taxa de aspiração e o uso de uma solução de óleo mineral em xileno para o ajuste da viscosidade entre soluções das amostras e de calibração devem ser destacados. Testes de precisão (repetitividade e precisão intermediária) mostraram valores adequados, comprovando a robustez do método, e os limites de detecção estiveram confortavelmente abaixo daqueles propugnados pelas legislações brasileira e internacional. A exatidão foi confirmada por testes de recuperação e pela participação em exercícios interlaboratoriais de proficiência promovidos pela Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP). A determinação dos 4 elementos por F AAS traz evidentes vantagens econômicas ao produtor, uma vez que se trata de um equipamento mais barato na sua aquisição e manutenção.Recently, ABNT (Brazilian Association of Technical Standards) has presented a set of norms related to the determination of Na, K, Mg and Ca in biodiesel, recommending procedures similar to those of the European and American norms. However, it has also introduced an alternative norm (ABNT NBR 15556) wherein these 4 elements can be determined by flame atomic absorption spectrometry (F AAS). This work presents the studies that have supported this proposal and compares the performance of linear source equipment with a continuous source one in the application of the norm. Among the optimized factors, the low aspiration rate and the use of mineral oil solution in xylene to adjust the viscosity between samples and calibration solutions are highlighted. Precision tests (repeatability and intermediary precision) have shown adequate values, confirming the robustness of the method. Limits of detection were suitably below the legislation limits. The accuracy was confirmed by recovery tests as well as by the participation in interlaboratory proficiency tests promoted by the National Agency on Oil, Natural Gas and Biofuels (ANP, Brazil). The determination of these 4 elements by F AAS brings evident economic advantages to the producer, once F AAS is less expensive to purchase and maintenance.Keywords: biodiesel, ABNT NBR 15556 norm, metals, flame atomic absorption spectrometry Oliveira et al. 1401 Vol. 23, No. 7, 2012 Introduction Nowadays biodiesel represents a real alternative to diesel for internal combustion engines. The use of biodiesel has the potential to lower the environmental impact o...

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