Heronides Adonias Dantas Filho

Simultaneous Spectrometric Determination of Cu 2+ , Mn 2+ and Zn 2+ in Polivitaminic/ Polimineral Drug Using SPA and GA Algorithms for Variable Selection

Este artigo apresenta uma aplicacao do metodo para determinacao espectrofotometrica simultânea dos ions divalentes de cobre, manganes e zinco a analise de medicamento polivitaminico/polimineral. O metodo usa 4-(2-piridilazo) resorcinol (PAR), calibracao multivariada e tecnicas de selecao de variaveis e foi otimizado o empregando-se o algoritmo das projecoes sucessivas (APS) e o algoritmo genetico (AG), para escolha dos comprimentos de onda mais informativos para a analise. Com essas tecnicas, foi possivel construir modelos de calibracao por regressao linear multipla (RLM-APS e RLM-AG). Os resultados obtidos foram comparados com modelos de regressao em componentes principais (PCR) e nos minimos quadrados parciais (PLS). Demonstra-se a partir do erro medio quadratico de previsao (RMSEP) que os modelos apresentam desempenhos semelhantes ao prever as concentracoes dos tres analitos no medicamento. Todavia os modelos RLM sao mais simples pois requerem um numero muito menor de comprimentos de onda e sao mais faceis de interpretar que os baseados em variaveis latentes.

Distribution and availability of copper, iron, manganese and zinc in the archaeological black earth profile from the Amazon region

Os solos de terra preta arqueologica sao ricos em materia orgânica, contem fragmentos cerâmicos e artefatos liticos e apresentam nutrientes em concentracoes mais elevadas do que outros tipos de solos. Com o intuito de contribuir com informacoes sobre concentracoes de micronutrientes disponiveis em solos de terra preta, foram avaliadas atraves de extracoes quimicas sequenciais, a distribuicao e disponibilidade de Cu, Fe, Mn e Zn em um perfil de terra preta arqueologica no municipio de Juruti, estado do Para. As maiores concentracoes de Cu, Fe, Mn e Zn no perfil sao encontradas na fracao residual. Este estudo mostrou que ferro, manganes e zinco sao preferencialmente disponiveis a partir das fracoes, associados aos oxidos de Fe-Mn, variando de 1265,39 a 1818,12 mg kg-1, 0,83 a 48,51 mg kg-1 e 1,92 a 12,05 mg kg-1, respectivamente, e o cobre a partir da materia orgânica, variando de 0,13 a 0,45 mg kg-1.

Comportamento do mercúrio em perfis de solos do sítio Ilha de Terra-Caxiuanã, Pará

Behavior of mercury in soil profiles with archaeological black earth (ABE) and surroundings area (SA) from Sitio Ilha de Terra, Caxiuana, can provide information on anthropogenic activity of the Amazonian habitat. The samples of ABE and SA soil profiles were submitted to mineralogical chemical (total and sequential) analysis. The data show that the Hg occurs mainly in goethite and kaolinite in the two soil profiles. The highest concentrations of Hg and Fe are observed in the SA profile. These results indicate that the prehistoric human occupation contributed to the decrease of the concentration of Hg in soil ABE from Caxiuana.

Evaluation of the physicochemical parameters and inorganic constituents of honeys from the Amazon region

The aim of this study was to determine the physicochemical composition and inorganic constituents of seventeen honey samples produced in Amazon region by different bee species (Scaptotrigona sp., Melipona fasciculata, Melipona flavolineata and Apis mellifera). The physicochemical parameters evaluated were pH, acidity, soluble solids, moisture, density, reducing sugars, apparent sucrose and hydroxymethylfurfural. Ba, Ca, Cd, Cu, Fe, Mg, Mn, P, Pb and Zn contents were determined in honey samples by inductively coupled plasma optical emission spectrometry. Na and K contents were measured in honeys by flame atomic absorption spectrometry. Honey samples were digested in a microwave oven using diluted nitric acid and hydrogen peroxide. The analytical results obtained in this study were evaluated by analysis of certified reference material (GBW 07604 Poplar leaves). The results of physicochemical analyzes showed significant differences (p < 0.05) among the species, mainly regarding moisture content, acidity, density and soluble solids. In general, the honeys from Scaptotrigona sp. showed the highest levels of minerals (Ca, Cu, K, Mg), being a good source of minerals, as well as presented significant differences (at 5% of significance) in relation to the other studied species. Thus, the results indicate new information about the composition of these honeys and emphasize the need for the implementation of specific legislation for quality assessing of honey from stingless bees.

Classificação multivariada de ervas medicinais da Região Amazônica e suas infusões de acordo com sua composição mineral

In this study, the mineral composition of leaves and teas of medicinal plants was evaluated. Ca, Cu, Fe, Mg, Mn e Zn were determined in the samples using flame atomic absorption spectrometry. Principal component analysis was applied to discriminate the samples studied. The samples were divided within the 2 groups according to their mineral composition. Copper and iron were the variables that contributed most to the separation of the samples followed by Ca, Mg, Mn and Zn. The information in the principal component analysis was confirmed by the dendrogram obtained by hierarchical cluster analysis.

Flow-batch analyser for preparation of calibration standard mixtures in simultaneous multicomponent spectrometric analysis

The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simul- taneous determination of several chemical species. However, when this methodol- ogy is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high opera- tional cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu 2+ , Mn 2+ and Zn 2+ in polyvitaminic and polymineral pharmaceutical formula- tions, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the prepara- tion of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples h -1 can be carried out with the proposed flow-batch analyser.

ESTUDO DA QUALIDADE DA GASOLINA TIPO A E SUA COMPOSIÇÃO QUÍMICA EMPREGANDO ANÁLISE DE COMPONENTES PRINCIPAIS

The type A gasoline samples were analyzed by gas chromatography with flame ionization detector (GC-FID) which allowed quantifying and classifying of the various compounds into different classes of hydrocarbons. Several physicochemical parameters were evaluated according to the official methods in order to compare the results obtained against the limits established by the Agencia Nacional de Petroleo, Gas Natural e Biocombustiveis (ANP, 2011). Additionally, principal component analysis (PCA) was applied to discriminate the samples studied, which revealed the separation of four groups according to their chemical composition determined in samples collected from the eight fuel distributors in the State of Para.

Adsorção de nitrato em caulinita a partir de rejeito de caulim modificado com uréia

This study evaluates the the efficiency, feasibility and spontaneity of the adsorption of nitrate ion in natural and modified kaolinite with urea, using as starting material kaolin waste processing from Jari River. The materials were characterized by X-ray diffraction, X-ray fluorescence, Fourier transform IR spectroscopy (XRD, XRF and FTIR, respectively). The equilibrium pH measurements were performed by potentiometry and the equilibrium concentrations (Ce) nitrate was measured by ion chromatography. Amounts adsorbed at equilibrium (qe), distribution constant (Kd = qe / Ce), separation factor (RL) and variation of Gibbs free energy (ΔG °) were calculated based on experimental data adsorption. The results of XRD and FTIR confirmed the formation of the kaolinite-urea from treatment carried out on kaolin waste. The following data were obtained from the adsorption of nitrate on natural kaolin waste and treated with urea: qmax = 18.17 and 14.1 mmol kg-1; Kd = 0.7 to 2.2 and 0.45 - 1.5 L kg-1; RL = 0.35 to 0.85 and 0.25 to 0.80; ΔG ° = -9.3 to -5.8 and -9.1 to -5.4 kJ mol-1, respectively. The values of Kd , ΔGo and RL are typical of physisorption processes, feasible and spontaneous and those qmax indicate that the retention of nitrate on natural kaolin waste is more efficient than on kaolin waste modified with urea.

Determination of Ca, Mg, Na, and K in Biodiesel of Oilseed from Northern Brazil

In this study flame atomic absorption spectrometry (FAAS) was used to determine calcium, magnesium, sodium and potassium contents in biodiesel produced with different oilseeds (bacaba, bacuri, brazil nut, palm). These samples were digested using open system with conventional heating with concentrated nitric and sulfuric acids plus hydrogen peroxide. The element concentrations varied considerably in the different samples. The limits of detection obtained were < 0.3 mg/kg.

Mineral Composition of Amazonian Fruits by Flame Atomic Absorption Spectrometry Using Multivariate Analysis

This study aimed to evaluate the mineral composition in native and non-native Amazonian fruits using flame atomic absorption spectrometry (FAAS) and multivariate methods, such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), in order to conduct a more thorough evaluation of the original data. The accuracy was checked by certified reference material analysis (Poplar leaves) and spike experiments. The results of the analysis were in agreement with the certified values, with analytical recoveries for all analytes in an acceptable range from 82 to 113%, and relative standard deviations (RSD) were in the range of 0.2–18%. Furthermore, PCA explained 68% of the total variance, while HCA confirmed the correlations found in the PCA, allowing for the evaluation of the degree of similarity between the fruits studied. These results will be used to better understand the distribution of inorganic constituents within these Amazonian fruits.