Abstract This study shows the results obtained of evaluation and comparison of chemical analysis and ecotoxicity for evaluated the quality of water contaminated with gasoline after Fenton process. The process Fenton was efficient to remove the aromatics organic compounds such as benzene, toluene and xylenes from water contaminated with gasoline. At 90 minutes of reaction time, the concentration measured of aromatics compounds by gas chromatography were less than limit of quantification (0.05mg L-1). This value is in accordance with the limits established by Brazilian legislation for the effluents discharge. On the other hand, analysis of total phenols and dissolved organic carbon demonstrated at 120 minutes that all dissolved organic compound and total phenols are not totally removed even though benzene, toluene and xylenes were almost completely removed. Phytotoxicity tests using Sinapis alba as biological response showed that water contaminated with gasoline are not toxic, however these results was probably influenced by volatilization of aromatics compounds during the assay. Differently, the ecotoxicity using Daphnia magna showed that water contaminated with aromatic compounds is toxic, but after 120 minutes of treatment the toxicity was reduced more than 50%. Then, Daphnia magna was the better bioindicator to evaluate the efficiency of Fenton process since these results were according with response of dissolved organic carbon and total phenol showing the toxicity of intermediates produced during the Fenton process.

The ultrasound-assisted extraction (UAE) is an alternative approach for the total lipid content determination in food samples. The high extraction efficiency, being less time-consuming and with the possibility of using less toxic solvents are the main advantages of UAE. It is, thus, an excellent alternative to be applied as a laboratory experiment for undergraduate students. The UAE procedure was optimized and the extraction parameters, such as extractor solvent, time and frequency of the ultrasound, were evaluated. The accuracy of the UAE procedure was evaluated by comparing the obtained results with those found by the traditional lipids extraction approach. The results showed that the lipids content found in the analyzed samples by using UAE were in agreement with the results obtained by the traditional lipids extraction. Therefore, the optimized UAE procedure was proposed as a laboratory experiment to 15 groups of undergraduate students to introduce the subjects of an alternative approach for total lipids determination in food samples. The results obtained showed that 80% of the student groups found results for total lipid contents in agreement with those found by traditional lipids extraction method. The proposed UAE procedure as a laboratory experiment proved to be simple and easy to be applied to undergraduate students.

Resumo: O presente artigo objetiva apresentar resultados de um estudo realizado sobre a utilização de saberes populares como ponto de partida para o ensino de conceitos químicos, articulando os diversos saberes sob o enfoque CTS. O trabalho foi realizado com 30 alunos da 3ª série do ensino médio de um colégio da rede estadual de ensino, da região sul do Paraná, Brasil. A abordagem metodológica foi a qualitativa, de natureza interpretativa, com observação participante. A coleta de dados se deu por meio de questionários, apresentação e discussão dos resultados das pesquisas bibliográficas, elaboração e análise de mapas conceituais, produção de infográficos (historinhas). A pesquisa demonstrou que a utilização dos saberes populares se constituiu num fator motivador e de apoio para a aprendizagem, possibilitando a contextualização dos conteúdos, tornando o ensino de Química mais atraente e significativo, facilitando, dessa maneira, a criação de estruturas cognitivas e mudanças de perfil conceitual.

Abstract: This article presents a general objective to demonstrate the possibility of using popular knowledge as a starting point for teaching chemical concepts, using the diverse knowledge of the STS approach. The study was conducted with 30 students of the 3rd year of a state high school, in the southern region of Paraná state, in Brazil. The methodological approach was qualitative, interpretative in nature, and used participant observation. Data collection was through questionnaires, presentation and discussion of the results of bibliographic research, preparation and analysis of conceptual maps, and infographics production (stories). The research has shown that the use of popular knowledge constituted a motivating factor and support for learning, enabling the contextualization of content, making chemistry education more attractive and meaningful, thus facilitating the creation of cognitive structures and conceptual profile change.

Nos últimos anos o consumo de achocolatados tem aumentado, principalmente pelo público infantil. Dessa maneira o controle de qualidade do produto em relação a sua composição, principalmente quanto à concentração dos minerais, torna-se importante para facilitar a escolha do produto pelo consumidor. Um método simples e rápido para a determinação de Fe, K e Na em amostras de achocolatado utilizando extração assistida por ultrassom foi proposto. As análises foram realizadas por fotometria de chama e espectrometria de absorção atômica com atomização em chama (FAAS). O método proposto mostrou-se simples, rápido e preciso, apresentando limites de detecção (LOD) para o método de 10 mg.100g-1 para K e Na e 0,2 mg.100g-1 para Fe, e valores de RSD menores que 13%. Foram analisadas 10 amostras de achocolatado em pó de diferentes marcas e as concentrações obtidas comparadas aos valores estabelecidos pela Tabela Brasileira de Composição de Alimentos (TACO) e aos valores informados nos rótulos dos produtos. Os resultados obtidos, para a maioria das amostras, não estavam de acordo com os valores estabelecidos na tabela TACO e com os valores informados nos rótulos.

In recent years the consumption of chocolate powder has been increasing, mainly by kids, and for this reason quality control of the product in relation to its composition, especially regarding the mineral concentrations, is important to facilitate the choice of product by the consumers. A simple and quick method for the determination of Fe, K and Na in chocolate powder samples using ultrasound assisted extraction was proposed. The measurements were carried out using photometric detection and atomic absorption spectrophotometry with flame atomization (FAAS). The method was shown to be simple and accurate, with detection limits (LOD) of 10 mg.100g-1 for K and Na and 0,2 mg.100g-1 for Fe, and RSD values below 13%. To check the efficiency of the method, the results were compared with acid digestion. Ten chocolate powder samples of different brands were analyzed, and the concentrations obtained compared with those found in the Brazilian Table of Food Composition (TACO) and also with the values informed on the product labels. For the majority of samples the results obtained were not in accordance with the values established by the TACO tables or with those printed on the labels.

OBJETIVO: Este estudo teve como objetivo avaliar o impacto da suplementação na dieta de gestantes e de lactantes com ácidos graxos ômega-3 docosahexaenoico, sob a forma de óleo de peixe, e sua influência na composição do leite humano. MÉTODOS: A amostra foi constituída de 60 gestantes, com idade entre 18 e 38 anos, saudáveis, com padrão alimentar adequado e não fumantes. A intervenção consistiu na suplementação da dieta com cápsulas de óleo de peixe, totalizando um consumo diário de 315mg de ácido docosahexaenoico e 80mg de ácido eicosapentaenoico, no período entre o terceiro trimestre de gravidez e o terceiro mês após o parto. O teor de lipídeos totais e do perfil de ácidos graxos foi determinado pelos métodos de crematócrito e de cromatografia gasosa. Para a análise dos dados foi utilizada estatística descritiva e nível de significância de p<0,05. RESULTADOS: Entre o grupo sujeito à dieta suplementada (cápsulas de óleo de peixe) e o grupo controle (cápsulas contendo amido de milho como excipiente), não se constatou diferença estatística quanto aos valores totais de lipídeos. Entretanto, no leite das mães do primeiro grupo, a suplementação com óleo de peixe mostrou teores mais elevados na concentração dos ácidos docosahexaenoico e eicosapentaenoico, nos tempos 30 e 60 dias, demonstrando que um maior consumo de ômega-3 pode influenciar na sua concentração no leite humano. CONCLUSÃO: Considerando a importância do ácido docosahexaenoico no período neonatal, é adequado incrementar com ácidos graxos poliinsaturados de cadeia longa a alimentação de gestantes e de lactantes, o que pode ocorrer pela suplementação da dieta com óleo de peixe.

OBJECTIVE: This study assessed the impact of supplementing the diet of women during pregnancy and lactation with fish oil containing the omega-3 fatty acid docosahexaenoic acid, and its influence on the composition of human milk. METHODS: The sample comprised 60 women aged 18 to 38 years with appropriate dietary pattern, all of them healthy and nonsmokers. The intervention consisted of a daily supplementation with fish oil capsules that corresponded to a daily intake of 315mg of docosahexaenoic acid and 80mg of eicosapentaenoic acid during the third trimester of pregnancy and the first three months postpartum. The total fat content and fatty acid profile of their milk were determined by creamatocrit and gas chromatography. Descriptive statistics were used for data analysis and the significance level was set at p<0.05. RESULTS: There was no statistical difference between the fat contents of the study (fish oil capsules) and control (capsules containing corn starch as filler) groups. However, the milk of women taking fish oil contained higher docosahexaenoic and eicosapentaenoic acid levels 30 and 60 days after delivery. These results demonstrate that high omega-3 intake can influence its concentration in human milk. CONCLUSIONS: Given the importance of docosahexaenoic acid in the neonatal period, it is appropriate for pregnant and breastfeeding women to supplement on long-chain polyunsaturated fatty acids, which may be done by adding fish oil to the regular diet.