Análise potenciométrica de redissolução com ultramicroeletrodos: fundamentos e aplicações na determinação de metais traços

Nobre, Ana Lúcia da Rocha; Mazo, Luiz Henrique

doi:10.1590/s0100-40421997000400012

Cited by 5 publications

(5 citation statements)

References 35 publications

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“…As figuras 14 e 15 mostram os potenciogramas típi-cos para a determinação de Zn 2+ em amostra de líquido de conserva de palmito in natura e Pb 2+ em amostra de líquido de conserva de cogumelo com um UME de Pt de 10 µm recoberto com Hg, juntamente com as respectivas curvas analíticas. Esta técnica apresenta inúmeras vantagens que estão discutidas em um trabalho submetido a esta revista 49 . …”

Section: B Eletroanalíticaunclassified

Ultramicroeletrodos. Parte II: construção e aplicações

et al. 1998

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Recebido em 16/10/96; aceito em 14/1/97 ULTRAMICROELECTRODES. PART II: CONSTRUCTION AND APPLICATIONS. This work describes the techniques of construction and several applications of ultramicroelectrodes in electrochemistry and electroanalytical chemistry. Disc shaped UME are produced by embedding metal wires on insulating materials such as glass or epoxy resin. In the field of electrochemistry, UME have been applied in studies of the hydrogen evolution reaction and the electrocrystallization of metals. The negligible values of sensibility for ohmic drop and the enhanced mass transport rate by spherical diffusion are the main advantages of UME in these applications. New important conclusions regarding the phenomena under study were drawn from the experimental results. The applications in electroanalytical chemistry involved the determination of contaminants such as heavy metals and nitrites in natural waters and food products. The use of UME requires little sample manipulation and, in general, no need for oxygen removal or the addition of supporting electrolytes.

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Section: B Eletroanalíticaunclassified

Ultramicroeletrodos. Parte II: construção e aplicações

et al. 1998

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“…[2][3][4] As compared to voltammetric stripping analysis (VSA), PSA has several advantages, such as smaller dependence on the electrode surface reproducibility, robustness with respect to the presence of some electroactive organic species, applicability to the analysis of solutions with low ionic strength, no need for deoxygenation of the sample, lower background contributions. 5,6 In addition, PSA can be carried out with a simple and inexpensive instrumentation, which can be easily automated. In fact, the only physical parameters that need to be measured are potential and time.…”

Section: Introductionmentioning

confidence: 99%

Wavelet-Based determination of Cu and Pb in water samples using potentiometric stripping analysis with a Lab-Made potentiostat

Martins

Galvão

César

2009

J. Braz. Chem. Soc.

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Este artigo demonstra a possibilidade de se realizar uma determinação simultânea de chumbo e cobre em água mineral, de rio e de torneira mediante análise por redissolução potenciométrica empregando um potenciostato lab-made de baixo custo e um método de processamento de sinais baseado em wavelets. As concentrações encontradas para Pb(II) e Cu(II) situaram-se na faixa 3-7 µg L -1. Os desvios padrão relativos foram em média menores que 3%, o que é satisfatório tendo em vista as baixas concentrações dos analitos. Para comparação, a determinação foi também realizada empregando um equipamento comercial de alto padrão (µAutolab Type II, Eco Chemie).As médias e desvios padrão dos resultados foram similares aos obtidos com o potenciostato labmade. Não foi verificada diferença estatística significativa de acordo com um teste t pareado ao nível de confiança de 95%. This paper demonstrates the possibility of simultaneously determining lead and copper in mineral, river and tap water by potentiometric stripping analysis using a low-cost lab-made potentiostat and a wavelet-based signal processing method. Pb(II) and Cu(II) concentrations were found to be in the range 3-7 µg L -1. Relative standard deviations were on average smaller than 3%, which is satisfactory in view of the trace concentration. For comparison, the determination was also carried out by using a high-end commercial equipment (µAutolab Type II, Eco Chemie). The average and standard deviation of the results were similar to those obtained with the labmade potentiostat. No significant statistical difference was verified according to a paired t-test at a confidence level of 95%.

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“…A aplicação da eletroanálise com métodos bastante sensíveis para a medida de traços e ultra-traços de metais tornou-se comum nos últimos anos (NOBRE; MAZO, 1997 …”

Section: Voltametriaunclassified

Análise físico-química de amostras de méis de Apis mellifera e Meliponíneos

Pereira¹

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DEDICATÓRIA RESUMOAnálise físico-química de amostras de méis de Apis mellifera e Meliponíneos O mel de abelhas é um produto biológico muito complexo, cuja composição varia notavelmente em função da flora visitada pelas abelhas e das condições climáticas e edáficas da região onde foi produzido. Este trabalho teve como objetivos confrontar os resultados das análises físico-químicas entre as amostras de méis produzidos em diferentes localidades do Brasil por Apis mellifera e por Meliponíneos e investigar se o mel produzido por essas abelhas nas suas diferentes regiões de origem apresenta níveis toleráveis de contaminantes inorgânicos. ABSTRACT Physico-chemical analysis of honey samples of Apis mellifera and MeliponidThe honeybee is a very complex biological product, whose composition varies markedly depending on the plant visited by the bees and the weather and soil conditions in the region where it was produced. This study aimed to compare the results of physicochemical analysis between the samples of honey produced in different locations in Brazil by Apis mellifera and Meliponid and to investigate whether honey produced by these bees, in different regions of origin, has tolerable levels of inorganic contaminants. To this end, we evaluated 56 samples of honey from A. mellifera and 56 samples of honey from Meliponid from the states of Bahia, Minas Gerais, Mato Grosso do Sul, Paraíba, Piauí, Paraná, Santa Catarina and São Paulo, for the following parameters: moisture content, water activity, viscosity, pH, free acidity, formol index, reducing sugars, apparent sucrose, ash content, color, electrical conductivity, hydroxymethylfurfural, diastase activity and metals (Hg ). Differential Pulse Anodic Stripping Voltammetry (DPASV) technique was used to quantify the metals, and, to the other analysis, conventional and suitable methods for honey were used. The results showed that the current legislation, referring to the honey of A. mellifera, is not appropriate for the parameters reducing sugars, moisture content and diastase activity of some species of Meliponid. It was concluded that the species A. mellifera, Tetragonisca angustula, Melipona quadrifasciata, M. scutellaris, M. mandacaia, M. fasciculata, M. subnitida produce honeys with different and specific physico-chemical characteristics. For all species studied, levels of inorganic contaminants found in honey were tolerable to human health. The honey produced by A. mellifera showed variations in physicochemical water activity, viscosity, free acidity, formol index, reducing sugars, electrical conductivity, hydroxymethylfurfural, diastase activity and the mineral zinc, depending on the different locations where they were produced.

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Análise potenciométrica de redissolução com ultramicroeletrodos: fundamentos e aplicações na determinação de metais traços

Cited by 5 publications

References 35 publications

Ultramicroeletrodos. Parte II: construção e aplicações

Ultramicroeletrodos. Parte II: construção e aplicações

Wavelet-Based determination of Cu and Pb in water samples using potentiometric stripping analysis with a Lab-Made potentiostat

Análise físico-química de amostras de méis de Apis mellifera e Meliponíneos

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