OPTIMIZATION OF THE EXTRACTION OF ANTHOCYANINS PRESENT IN BLACK BEANS AND IMPREGNATION OF THE EXTRACT IN NATURAL POLYMERIC MATRIX FOR USE AS A pH INDICATOR. In this work, a method of extracting natural indicators, anthocyanins, present in black beans was optimized. The best extraction condition was obtained with 50 g of beans and 93 g of water, under agitation at 150 rpm, at a temperature of 40oC for 24 h. The wavelengths of greatest absorption for the indicator in its acidic and basic form were 523 nm and 620 nm respectively and these wavelengths were used to determine the pKa of the indicator. At least three pKa values were observed: 1.9; 7.2 and 10.7. A simplified condition for anthocyanins extraction, the same amount of water, tap water in these case, and beans kept together for 12 h without agitation and temperature control, was also evaluated. Both extracts were impregnated with qualitative filter paper, coffee filter paper and cotton buds and the materials impregnated with the indicator were tested with solutions of HCl, vinegar, NaOH and milk of magnesia. A comparison between the impregnated material and a universal pH indicator paper using buffer solutions pH 4.0, 7.0, 10.0 and 11.2 proved the applicability of the developed material since it presented adequate distinction in its color for the different pH conditions.

Resumo Carvão ativado é um material que desponta para o uso da adsorção de contaminantes em águas, no entanto seu uso é mais restrito ao carvão vegetal do que ao mineral, principalmente devido ao seu maior custo (~ 40%), uma vez que é um combustível fóssil extraído da terra através da mineração. Assim, o caroço de pêssego, proveniente de rejeitos de indústrias alimentícias, pode ser uma boa alternativa para a remoção de contaminantes em meio aquoso. O objetivo deste estudo foi o desenvolvimento de um carvão ativado de baixo custo proveniente de caroços de pêssego para a remoção de atrazina em meio aquoso. Estudos de caracterização e experimentos em batelada foram realizados para investigar os efeitos de dosagem do carvão, concentração de atrazina, tempo de contato e pH do meio de adsorção, na remoção de atrazina. A partir dos resultados do delineamento experimental, observou-se excelente remoção do analito em condições próximas a do meio ambiente, como pH = 6,5, temperatura ambiente e tempo de agitação de 10 minutos, buscando sempre um menor custo de energia e tempo. A aplicação por sistema de batelada foi sugerida como versátil para aplicação em problemas sazonais, como a contaminação por pesticidas.

Abstract Activated carbon is commonly used as a material for contaminant-adsorption processes in aqueous systems. However, its use is more restricted to charcoal than to coal, for the most part, in view of the fact of the higher cost (~ 40%) if the mineral is a fossil fuel which needs to be extracted from the earth by mining. For this reason, the peach stone that comes from alimentary industrial tailings can be a good choice for the separation of pollutants from aqueous suspensions and other soluble substances. The purpose of this research was the development of a low-cost filter, using stones to remove atrazine from water. Appraisal and characterization studies were performed along with batch experiments to investigate dosing effects of the activated carbon, atrazine concentration, contact time, and adsorption pH on removal procedures. From the results of the experiment, an excellent removal of the analyte in question was observed under conditions that can be considered as close as possible to the environment, such as pH = 6.5, room temperature and 10 minutes of agitation time, always choosing the best alternative with the lowest cost of energy and time. Batch system application has been recommended as versatile for utilization in seasonal problems such as pesticide contamination.

Resumo O carvão ativado pulverizado quando bem embalado e estocado não possui um prazo de validade regulamentado. Em geral, esta validade é determinada de acordo com requisitos estabelecidos pelo próprio fabricante e está diretamente relacionada a uma estimativa de tempo superior ao tempo em que o produto ficará estocado no cliente até a sua utilização. Neste trabalho, avaliou-se a eficiência de carvões ativados de base seca e umectados, relacionando parâmetros de capacidade adsortiva (índice de iodo e umidade) destes materiais com o tempo. Os carvões contendo superfície alcalina não apresentaram variação nos parâmetros avaliados ao longo do tempo de armazenamento, pois não apresentaram significância estatística, uma vez que os valores de F regressão <F crítico e os valores de p > 0,05, tanto para base seca como úmida. Dos carvões com caráter ácido (pH corrigido), apenas um tipo foi mais sensível à adsorção de umidade e iodo ao longo do tempo. A partir da equação de reta oriunda da análise de regressão linear para este carvão, obteve-se a correlação Índice de Iodo = 824 - 0,370 x dias, indicando que o tempo de armazenamento para este material foi igual a 605 dias, garantindo que o valor do índice de iodo seja igual ao valor limite de 600 mg I2.g-1 carvão.

Abstract The pulverized activated carbon, when well packed and stored, doesn’t have either a regulated or approved shelf life. In general, this expiration date is determined based on the established requirements coming from the manufacturer itself and it is directly related to an overestimation of the time that the product is held in the customer storage location until its use. In this analysis, the research has assessed the efficiency of the moistened and the dry activated carbon powder, relating parameters of adsorption capacity (numbers of iodine and humidity) in these materials with time information. The charcoals containing alkaline surface didn’t exhibit a variation in the parameters evaluated along the storage time, since they didn’t feature statistical significance, once the F regression < F critical and the rate of p > 0.05, both for dry and wet basis. From the viewed acid carbons (with corrected pH), there was only one which got sensitive to moisture and iodine adsorptions over time. From the equation of the line originated by analysis of regression for this charcoal, the following correlation was obtained: Iodine Index=824-0.370 x days, showing that the storage time for the carbon was equal to 605 days, assuring that the right value of iodine index is equivalent to the limit of 600 mg I2 g-1 carbon.

Voltammetry using mercury electrode as working electrode has been employed in the determination of organic and inorganic compounds in several samples. A review on the applications of this analytical tool is present, covering the period of the last ten years. The emphasis of this work is directed to the hanging mercury drop electrode (HMDE), its advantages, disadvantages and applications. Voltammetric measurements are easily carried out, and present low cost. The review discusses that the use of mercury in the measurements can be a limitation due the toxicity of the element. However, nowadays the necessary of volume of Hg in the measurements is very small, and it can be reused. Thus, the correct disposal of the small amount of waste generated can be minimize environmental risks and human health, according to the principles of Green Chemistry.

Resumo O objetivo deste trabalho consiste em desenvolver e validar uma metodologia que reduza o tempo de digestão e o consumo de reagentes para determinar minerais em farinha de milho. No Brasil, a metodologia padrão utilizada é a descrita pelo AOAC, que consiste na calcinação da amostra em altas temperaturas, por longo período, o que torna o processo dispendioso e moroso. Neste trabalho, aplicou-se a digestão por via úmida das amostras usando HNO3, aquecimento em bloco digestor e solubilização final em banho ultrassom. Os testes de validação envolveram estudos de linearidade e faixa de trabalho, limites de detecção e de quantificação, precisão e exatidão. O tempo de digestão das amostras foi de 1h30min e as porcentagens de recuperação dos metais foram de 93% para Ca, 98% para Cu, 110% para Fe, 97% para Mg, 101% para Mn e 106% para Zn.

Abstract The aim of this work was to develop and validate methodology to reduce the digestion time and reagent consumption in the determination of minerals in maize flour. The standard methodology employed in Brazil is that described by AOAC. It consists of the calcination of the sample at high temperatures for a long period of time, making the process expensive and slow. In this work, a wet sample digestion method using HNO3 was employed, heating on a block digester with final dissolution in an ultrasonic bath. The validation tests involved linearity and working range studies, and the determination of the detection and quantification limits, accuracy and precision. The sample digestion time was 1:30 h and the percent recoveries for the metals were 93% for Ca, 98% for Cu, 110% for Fe, 97% for Mg, 101% for Mn and 106% for Zn.

Infusions of yerba mate obtained at different stages of industrialization were evaluated to determine the bioavailable fraction of Al. Adsorptive Cathodic Stripping Voltammetry using DASA (complexing agent) was applied to determine the labile fraction of Al at pH 5.0 and pH 8.0 for the total fraction of dissolved Al. The results indicate that on average 60% of Al is complexed with organic compounds, minimizing their bioavailability; however, the labile fraction exceeds by up to 4 times the maximum weekly intake recommended by the World Health Organization.

Trace metal content of three fish species harvested from a tank located in the City of Guarapuava-PR, Brazil were determined by digestion and voltametry. Trace metal content in fish samples were 0.10-1.30 µg/g (muscle) and 0.45-15.90 µg/g (liver) for chromium, 0.35-2.56 µg/g (muscle) and 2.32-34.30 µg/g (liver) for lead. The levels of lead and chromium in fish samples were higher than the recommended legal limits for human consumption. To assess the dietary intake of Cr and Pb by fish, weekly intake was calculated based on average metals contents and weekly consumption of fish and it compared with PTWI (Provisional Tolerable Weekly Intake). The Cr and Pb have achieved up to 25 and 45%, respectively, of PTWI recommended by WHO/FAO.

This work was performed to evaluate the distribution of metals Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the sediment surface in the Itaipu Lake-PR-Brazil. It was also performed to measurement the pH, phosphorus, organic carbon and particle size. In accordance of international criteria of quality of sediment, the results indicate an anthropogenic collaborations since some metals reached an excessive values. The factor of contamination was also used to evaluate the levels of contamination. The levels of Cu and Pb indicate a moderate contamination, so that it's possible to do harm to the balance of the ecosystem studied.

Propolis is mostly used as hydroalcoholic extract. Recently there has been a growing number of patents dealing with new solvents for preparing propolis extracts. This study aimed to prepare edible oil propolis extracts and compare their chemical composition and biological activity with ethanolic propolis extracts. ESI-MS and spectrophotometric methods were used for qualitative and quantitative analyses, respectively. Antibacterial activity was evaluated by diffusion in agar. Cytotoxicity was tested by MTT assay using tumor cell lines. The oil is able to extract bioactive compounds from propolis. Further studies are needed to improve extraction efficiency and to characterize the active components.

A determinação seletiva de As(III), As(V) e ácido dimetilarsínico (DMA) foi estudada pela técnica da geração de hidretos - espectrometria de absorção atômica. Os meios de redução selecionados permitiram a determinação de As(III) na presença de tampão citrato (0,4 mol/L, pH4,4), As(III) + As(V) no meio HCl 6 mol/L, após uma pré-redução com iodeto de potássio, e As(III) + DMA em CH3COOH 0,12 mol/L. O teor de arsênio total pode ser determinado no meio HCl 6 mol/L, após ser efetuada a pré-redução das formas As(V) e DMA com iodeto de potássio e cloreto estanoso. Os efeitos de interferência causados por diferentes íons metálicos foram, também, avaliados.

Hydride generation - atomic absorption spectrometry, using sodium tetrahydroborate(III) as a reductant, was used to form arsines selectively from inorganic arsenic(III) and arsenic(V), and dimethylarsinic acid (DMA). The selected reaction media allowed the rapid determination of arsenic(III) alone (citrate buffer 0.4 mol/L, pH 4.4), arsenic(III) + arsenic(V) (HCl 6 mol/L, after pre-reduction with potassium iodide) and arsenic(III) + DMA (acetic acid 0.12 mol/L). Total arsenic could be measured in HCl 6 mol/L, after arsenic(V) and DMA pre-reduction with a potassium iodide and stannous chloride mixture. Interference effects produced by heavy metal ions were also evaluated.