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Objetivo: avaliar a estabilidade química, microbiológica e teor de bioativos de farinhas de cladódios da palma, acondicionadas em sachês de alumínio e armazenadas em temperatura ambiente. Métodos: cladódios jovens de palma foram cortados e secos em estufa a 60ºC ± 5ºC/ 72h para a produção da farinha F0 (não armazenada) e farinhas F1 e F2 (acondicionadas em sachês de alumínio e armazenadas em temperatura ambiente, durante 15 e 30 dias, respectivamente). Realizou-se análises químicas, microbiológicas (Bacillus cereus, Escherichia coli e Salmonella sp) e determinação de bioativos nos cladódios e nas farinhas. Resultados: Os parâmetros avaliados mostraram que as farinhas em sua maioria apresentaram maiores valores (p0,05) de F0 e carotenoides totais e vitamina C da F2 apresentarem maiores (p

O crescente aumento das doenças crônicas não transmissíveis tem estimulado a procura do consumidor por alimentos funcionais. Portanto, este estudo teve como objetivo a preparação e caracterização de smoothies, utilizando o iogurte Skyr, a mucilagem de palma como espessante e a polpa de umbu para sua saborização. Foram elaboradas quatro formulações distintas de acordo com o processamento do Skyr (dessorado ou sem dessorar) e tipo de açúcar (açúcar de coco ou demerara). As formulações foram submetidas à caracterização química, determinação do teor de constituintes bioativos, atividade antioxidante e análise reológica. Dentre os resultados obtidos, destacaram-se na polpa de umbu valores elevados de ácido ascórbico (11,59 mg.100 g-1), compostos fenólicos (56,70 mg.EAG.100 g-1), atividade antioxidante total (59,85%) e baixo teor lipídico (0,31 mg.100 g-1). Os smoothies apresentaram acidez titulável e pH compatíveis com os exigidos pela legislação brasileira para iogurtes, baixo teor lipídico (1,16-3,03%), ácido ascórbico variando entre 5,82-10,36 mg.100 g-1 e os níveis de fenólicos totais, flavonoides amarelos e antocianinas foram maiores na formulação com Skyr dessorado e açúcar de coco. A atividade antioxidante oscilou de 12,06 a 28,09% para os diferentes smoothies. A mucilagem de palma promoveu efeito espessante e estabilizante nas formulações. Tanto a polpa quanto os smoothies apresentaram um comportamento reológico não-newtoniano. Portanto, os smoothies podem ser considerados como alimentos funcionais evidenciando-se que a utilização do umbu e a palma constituem-se como uma opção interessante para a inovação tecnológica na área alimentícia além de colaborar com uma alimentação saudável.

Sediments provide essential information about geochemical processes occurring in aquatic systems and are useful to monitor temporal changes in metals concentrations. In this work, we conducted a geochemical survey in the Rio de Ondas basin, situated in the inland cerrado area from the northeast Brazilian region, to establish environmental reference values to identify metal origins related to anthropogenic and natural sources. Also, we evaluated the temporal dynamics of soil to assess the anthropic pressure over the soil surface and its potential effects on geochemical compositions of sediments. To this end, we combined geochemical and Geographic Information System (GIS) information, including remote sensing imagery, X-ray diffraction analysis, and geochemical analytical tools. We applied multivariate statistical analysis, determination of Geoaccumulation Index (Igeo), and enrichment factors (EF) to interpret the dataset. The results showed that 47.35% of the Brazilian cerrado in this zone was suppressed due to agricultural activity expansion. Mineralogy analysis indicated the presence of quartz silicates, varying from 65.1% (w/w) to 86% (w/w). Overall, the sediments showed low metal contamination levels and moderate levels near urban centers, probably due to domestic sewage discharge. It was also observed in very similar proportions of mineral constituents, obtaining environmental reference data and their associations with the region's geological formation. Thereby, sediment geochemical compositions probably reflect weathering processes, which may accelerate due to landscape modifications induced by economic activities, notably agriculture.

This work presents a critical review of multivariate techniques employed for optimization of methods developed in food analysis. A comparison between the response surface methodologies has been performed, it evidencing advantages and drawbacks of these. Applications of the main chemometric tools (central composite and Box Behnken designs and Doehlert matrix) often utilized for optimization of sample preparation procedures and also instrumental conditions of analytical techniques for determination of organic and inorganic species in food samples are shown. Also, a brief discussion on the use of multiple responses and robustness test in food analysis has been presented.

A new procedure developed based on a preconcentration system using a dispersive liquid-liquid microextraction technique based on solidification of floating organic drop (DLLME-SFO) was combined with the molecular absorption spectrometry to determine uranium using 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) as the complexing reagent. The optimization step was performed using two-level factorial design and the Box-Behnken design. The parameters analyzed were pH, Br-PADAP volume, extractant solvent volume and disperser solvent volume. The method allowed determining uranium with a limit of detection of 0.46 μg L− 1, limit of quantification 1.53 μg L− 1. The enrichment factor was estimated to be 76-fold. The precision expressed as relative standard deviation (RSD) for uranium concentrations of 2 and 10 μg L− 1 was 4.91% and 1.85% (n = 15), respectively. Accuracy was assessed using recovery values ranging from 95.28% to 103.86%, which proves that this method does not suffer from a matrix effect and can be satisfactorily applied. The proposed method was applied to determine uranium in human milk samples. Fifteen samples were analyzed, and the uranium concentration ranged from 45.87 ± 3.62 μg L− 1 to 160.97 ± 7.00 μg L− 1.

Asphaltene precipitation is a complex and serious problem in all sectors of the oil industry because it has a severe and detrimental impact on oil production. Thus, it is crucial to investigate under which conditions asphaltenes precipitate in order to prevent or mitigate the effects. Several approaches have been reported in the literature regarding the modeling of asphaltene precipitation during oil production. The simplest one is the single-component solid model in which the precipitated asphaltene is considered a pure solid and the oil and gas phases are described by a cubic equation of state (EOS). These are the basic assumptions of the Nghiem and Coombe’s model. In this paper, based on this model, we make numerous improvements and simplifications such as reducing the number of parameters to be estimated and considering that the number of asphaltene fractions can vary according to the oil characteristics. The characterization method is performed using the exponential distribution and only the binary i...

O Parque Nacional Serra de Itabaiana está inserido numa região de ecótono entre os domínios fitogeográficos Mata Atlântica e Caatinga. Por ser uma das principais áreas de estudos científicos em Sergipe, existem trabalhos que abordam famílias botânicas e listagens da sua flora vascular. Entretanto, percebeu-se a necessidade de atualização e compilação das listas para melhor conhecimento da diversidade e conservação da flora local. Diante disso, elaborou-se um checklist a partir de publicações pretéritas e do banco de dados do Herbário da Universidade Federal de Sergipe (ASE). Foram registradas 124 famílias e 830 espécies, distribuídas entre Angiospermas (803 espécies), Samambaias e Licófitas (26) e Gimnospermas (1). As famílias de maior riqueza foram: Fabaceae (73 espécies), Poaceae (65), Cyperaceae (59), Rubiaceae (40) e Asteraceae (36). Ervas (41.2%), arbustos (24.7%) e árvores (17.6%) foram os hábitos mais representativos. Cento e setenta espécies são novas ocorrências para Sergipe, há uma nova espécie para a ciência, seis espécies raras, três em perigo de extinção, nove quase ameaçadas e três vulneráveis, além de 80 espécies endêmicas da Mata Atlântica e 13 endêmicas da Caatinga.Palavras chave: Checklist, coleção biológica, ecótono, florística.

This study proposes a methodology of determination of cadmium and manganese in food samples using an aqueous two-phase system without extracting agent with F AAS detection. In order to choose the best system for preconcentration, an experimental design with Doehlert matrix was employed, allowing the determination of the system composed by PEO400 + K2HPO4 + H2O with the best extraction efficiency. This same study verified that pH does not influence the extraction percentage. Still in the optimization stage, the best conditions were tie-line length = 53.3%w; mass ratio between bottom and top phases = 0.029; and extraction time = 18hs. The method reached values of LOD (0.45 µg.Kg−1 for Cd(II) and 6.4 µg.Kg−1 for Mn(II)), LOQ (1.5 µg.Kg−1 for Cd(II) and 21 µg.Kg−1 for Mn(II)) and enrichment factor (16 for Cd(II) and 45 for Mn(II)) suitable to determine both analytes in food samples. The intra and inter-day relative standard deviation ranged from 3.28 to 4.37%, and from 5.05 to 6.60% for Cd(II) and Mn(II), respectively. The analysis of the NIST 1575a certified sample had a recovery of 98.2% for cadmium, and NIST 1515 presented recovery of 99.2% for manganese, showing high accuracy. The method was applied to samples of green tea and soluble coffee, and the recovery tests obtained results ranging from 94.0 to 110%. Therefore, the proposed methodology is efficient and without using an extractor, being a highly accurate and environmentally safe alternative for the determination of trace levels of metal in food samples.

The present paper reports the advantages, drawbacks and applications of the main techniques of sample preparation employed during the determinations of total mercury and methylmercury in food matrices employing analytical methods such as: cold vapor atomic absorption spectrometry (CV AAS), cold vapor atomic fluorescence spectrometry (CV AFS), inductively coupled plasma mass spectrometry (ICP-MS), voltammetry, and neutron activation analysis. The use of slurry sampling, solid sampling, microwave assisted extraction, reflux system by cold finger and Vigreux column was discussed. Also a brief text on the use of chromatographic techniques for the speciation analysis of mercury is presented. A list of 134 references is cited and the analytical characteristics of some these procedures proposed are shown as tables.

Concentrations of 11 elements (P, Cu, Ni, Co, Pb, Ca, Mn, Fe, Zn, Cr and Al) were measured in leachate samples collected monthly from the municipal landfill in Jequié, Bahia, Brazil. P (0.943-23.8 mg L(-1)), Ca (19.90-129 mg L(-1)) and Fe (0.115-2.87 mg L(-1)) were found in the highest levels, while Cu (LOQ-0.230 mg L(-1)), Ni (LOQ-0.540 mg L(-1)), Co (LOQ-0.268 mg L(-1)), Pb (LOQ-0.563 mg L(-1)), Mn (LOQ-3.40 mg L(-1)), Zn (LOQ-0.594 mg L(-1)), Cr (LOQ-0.163 mg L(-1)) and Al (LOQ-2.27 mg L(-1)) were found in lower concentrations. Principal components analysis and hierarchical clustering analysis revealed two distinct groups associated with dry and rainy periods. Overall, this study revealed that concentrations of elements in landfill leachate vary temporally, and rainfall strongly influences their levels.

Caigua (in Brazil “maxixe do reino”) is a fruit that is generally consumed either cooked or even raw as salad. This fruit has been used as a food and also in folk medicine. In this work, the mineral composition of Caigua was determined for the first time. Twenty-nine samples from five farms located in the southwestern region of Bahia, Brazil were acquired and analyzed using inductively coupled plasma optical emission spectrometry. The elements determined in this fruit included calcium, magnesium, sodium, potassium, phosphorus, manganese, iron, zinc, copper and vanadium. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to evaluate the obtained results. The average concentrations of the determined elements (expressed as mg 100g−1) were as follows: 0.91 for sodium, 152 for potassium, 19.4 for phosphorus, 11.9 for calcium, 8.4 for magnesium, 0.074 for manganese, 0.21 for iron, 0.013 for copper, 0.13 for zinc and 0.015 for vanadium.

The mineral composition of Brazilian rice samples was determined and the data obtained were evaluated using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Nineteen commercial rice samples were analyzed, six being brown, seven parboiled and six white. The elements were determined employing inductively coupled plasma optical emission spectrometry (ICP OES), and the accuracy was confirmed using a certified reference material of rice flour. The PCA showed the formation of three clusters: a group with the brown rice samples, other with the parboiled rice samples and another of the white rice samples. PCA also showed that the brown rice samples are richer in minerals than the white and parboiled rice samples. Calcium, sodium, zinc and manganese in white rice samples are higher than in parboiled rice samples, while the parboiled rice has higher contents of iron, magnesium, strontium, potassium and phosphor. HCA also demonstrated formation of three major groups, confirming the results obtained by PCA. Application of HCA in the subgroups of rice samples clearly showed separation of rice brands and also separation between the raw and cooked samples. The mineral composition in the rice samples analyzed agrees with data reported by other authors. This paper revealed that the mineral compositions for white, brown and parboiled rice are significantly different.

Broccoli (Brassica oleracea L. var. Italica) is a vegetable food that belongs to the family Cruciferaceae, and it is a good source of vitamins and minerals. Among other characteristics, the kind of culture (conventional or organic), the climate of origin, and the way a vegetal will be consumed influence directly in the concentrations of minerals. The aim of this work was to determine mineral composition (Fe, Mn, Zn, K, Ca, Mg, and Na) of 16 broccoli samples collected in four cities of Bahia, Brazil, in summer and winter, from organic and conventional cultures. These elements were also determined in a lot of raw and cooked summer samples and then all results were evaluated using multivariate analysis. Broccoli samples were analyzed by inductively coupled plasma optical emission spectrometry after digestion with HNO3 and H2O2. The results expressed as milligrams of element per 100 g of sample demonstrated that the concentration ranges for conventional and organic broccoli varied, respectively, from 0.13 to 0.90 and 0.14–1.18, for iron; from 0.15 to 1.79 and 0.04–1.40, for manganese; from 0.20 to 1.58 and 0.17–1.28, for zinc; from 317.65 to 484.45 and 321.58–521.78 for potassium; from 7.14 to 153.50 and 9.38–131.55, for calcium; from 21.09 to 47.15 and 29.51–61.23, for magnesium; from 3.66 to 21.21 and 1.89–27.09 for sodium. The accuracy of the method was confirmed by analysis of a certified reference material of spinach leaves (NIST 1570a). The statistical evaluation of the obtained results showed that broccoli samples were not differentiated by city of origin, station, or culture. Nevertheless, by comparing raw and cooked samples, it was noticed a tendency of separation in the principal component analysis and hierarchical cluster analysis.

Inductively coupled plasma optical emission spectrometry was used to determine the elements present in Chinese cabbage (Beta vulgaris). The accuracy of the method was confirmed by analysis of a certified reference material of spinach leaves. The study involved 57 samples that were collected in 13 Brazilian cities. Average concentrations of elements found per gram of Chinese cabbage were as follows: 3.44 mg g−1 sodium, 5.09 mg g−1 potassium, 1.25 mg g−1 phosphorous, 0.85 mg g−1 calcium, 0.49 mg g−1 magnesium, 2.79 μg g−1 manganese, 9.50 μg g−1 iron, 0.74 μg g−1 copper, 14.28 μg g−1 zinc, and 6.44 μg g−1 strontium. Principal component analysis and hierarchical cluster analysis demonstrated that there is no systematic difference in the mineral composition between the cabbage samples that were analyzed.

In this work, the mineral composition of fresh bovine milk obtained from the milk-producing areas of the Brazilian State of Sergipe was examined. A dry-ashed digestion method and the ICP OES technique were used for the quantification of mineral elements ( e.g. , Ca, Mg, K, Na, P, Sr and Zn) in 27 samples of milk collected from properties located in milk-producing areas around Nossa Senhora da Gloria. The following ranges of values (% m/v) were obtained: 0.063 to 0.117 for Ca; 0.060 to 0.114 for P; 0.024 to 0.064 for Na; and 0.087 to 0.164 for K. The ranges of values (mg L − 1 ) for the other mineral elements were also found: 0.68 to 1.89 for Sr; 2.46 to 5.73 for Zn; and 54.2 to 109.9 for Mg. Additionally, the exploratory evaluation of the 27 milk samples was performed using principal component analysis (PCA) involving seven variables dealing with the effect of different management systems (conventional and organic) on milk composition. The results show that there are indeed differences between the mineral composition of milk from properties that use organic practices and those that use conventional management practices.

A procedure is proposed for the direct determination of manganese and iron in wine employing fast sequential flame atomic absorption spectrometry and the reference element technique to correct for matrix effects. Cobalt, silver, nickel and indium have been tested as reference elements. The results demonstrated that cobalt and indium at a concentration of 2 and 10 mg L−1 were efficient for quantification of manganese and iron, respectively. Under these conditions, manganese and iron could be determined with quantification limits of 27 and 40 μg L−1, respectively. The proposed method was applied to the determination of manganese and iron in 16 wine samples. The content of manganese varied from 0.78 to 2.89 mg L−1 and that of iron from 0.88 to 9.22 mg L−1. The analytical results were compared with those obtained by inductively coupled plasma optical emission spectrometry after complete mineralization using acid digestion. The statistical comparison by a t-test (95% confidence level) showed no significant difference between the results.

Levels of As, Cd, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb and Se in muscle, gill, stomach, liver, kidney and gonad tissues of six different fish species (Caranx latus, Bagre marinus, Archosargus rhomboidalis, Lutjanus synagris, Scomberomorus cavalla and Sphyraena guachancho) from the Todos os Santos Bay (Bahia State, Brazil) were evaluated. The elements were determined by inductively coupled plasma mass spectrometry (ICP-MS) after wet digestion using reflux system with a cold finger. The detected concentration ranges were as follows (mg kg-1 dry weight): < 0.49-27.31 for As, < 0.013-1.12 for Cd, 0.38-6.05 for Cr, 0.17-28.12 for Cu, < 0.092-1.19 for Li, 0.16-55.9 for Mn, < 0.034-1.24 for Mo, < 0.067-15.57 for Ni, < 0.013-0.60 for Pb, < 0.144 for Sb and 0.57-14.6 for Se. Highest concentrations of trace elements were observed in kidney, liver and gill tissues.

The present article describes fundamentals and applications of multivariate techniques used for the optimization of analytical procedures and systems involving spectroanalytical methods such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma optical emission spectrometry (ICP OES), and inductively coupled plasma mass spectrometry (ICP‐MS), considering the main steps of a chemical analysis. This way, applications of experimental designs in optimization of sampling systems, digestion procedures, preconcentration procedures, instrumental parameters of quantification steps of analytical methods, and robustness tests have been summarized in this work.

Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. This review covers separation and preconcentration procedures, such as electrochemical deposition, precipitation, coprecipitation, solid phase extraction, liquid-liquid extraction (LLE) and cloud point extraction (CPE), and consider the features of the their application with several spectrometric techniques.

The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.

The present paper proposes an on-line pre-concentration system for cadmium determination in drinking water using flame atomic absorption spectrometry (FAAS). Cadmium(II) ions are retained as 1-(2-pyridylazo)-2-naphthol (PAN) complex at the walls of a knotted reactor, followed of elution using hydrochloric acid solution. The optimization was performed in two steps using factorial design for preliminary evaluation and a Box–Behnken design for determination of the critical experimental conditions. The variables involved were: sampling flow-rate, reagent concentration, pH and buffer concentration, and as response the analytical signal (absorbance). The validation process was performed considering the parameters: linearity and other characteristics of the calibration curve, analytical features of on-line pre-concentration system, precision, effect of other ions in the pre-concentration system and accuracy. Using the optimized experimental conditions, the procedure allows cadmium determination with a detection limit (3 σ / S) of 0.10 μg L− 1, a quantification limit (10 σ / S) of 0.33 μg L−1, and a precision, calculated as relative standard deviation (RSD) of 2.7% (n = 7) and 2.4% (n = 7) for cadmium concentrations of 5 and 25 μg L− 1, respectively. A pre-concentration factor of 18 and a sampling frequency of 48 h−1 were obtained. The recovery for cadmium in the presence of several ions demonstrated that this procedure could be applied for the analysis of water samples. The method was applied for cadmium determination in drinking water samples collected in Salvador City, Brazil. The cadmium concentrations found in five samples were lower than the maximum permissible levels established by the World Health Organization.

In this work, multivariate optimization techniques were used to develop a method based on the ultrasound-assisted extraction for copper, manganese, nickel and zinc determination from rations for chicken nutrition using flame atomic absorption spectrometry. The proportions of extracting components (2.0 mol.L–1 nitric, hydrochloric and acetic acid solutions) were optimized using centroid-simplex mixture design. The optimum proportions of this mixture taken as percentage of each component were respectively 20%, 37% and 43%. Variables of method (sample mass, sonication time and final acid concentration) were optimized using Doehlert design. The optimum values found for these variables were respectively 0.24 g, 18s and 3.6 mol.L–1. The developed method allows copper, manganese, nickel and zinc determination with quantification limits of 2.82; 4.52; 10.7; e 9.69 µg.g–1, and precision expressed as relative standard deviation (%RSD, 25 µg.g–1, N = 5) of 5.30; 2.13; 0.88; and 0.83%, respectively. This method was applied in the analytes determination from chicken rations collected from specialized commerce in Jequié city (Bahia State/Brazil). Application of paired t-test at the obtained results, in a confidence level of 95%, does not show significant difference between the proposed method and the microwave-assisted digestion. Neste trabalho, técnicas de otimização multivariada foram usadas no desenvolvimento de um método com base na extração assistida por ultrassom para determinação de cobre, manganês, níquel e zinco em rações para nutrição de frangos usando espectrometria de absorção atômica com chama. As proporções dos componentes extratores (soluções 2.0 mol.L–1 dos ácidos nítrico, clorídrico e acético) foram otimizadas usando-se um planejamento de misturas centróide simplex. As proporções ótimas desta misturas representadas em percentagem de cada componente foram, respectivamente, 20, 37 e 43%. As variáveis de método (massa da amostra, tempo de sonicação e concentração final do ácido) foram otimizadas usando-se planejamento Doehlert. Os valores ótimos encontrados para estas três variáveis foram respectivamente 0,24g; 18s e 3,6 mol.L–1. O método desenvolvido permite a determinação de cobre, manganês, níquel e zinco com limites de quantificação de 2,82; 4,52; 10,7 e 9,69 µg.g–1, e precisão expressa como desvio padrão relativo (%SRD, 25 µg.g–1, N = 5) de 5,30; 2,13; 0,88 e 0,83%, respectivamente. Este método foi aplicado na determinação de analitos em rações de frango coletadas no comércio especializado da cidade de Jequié (Estado da Bahia/Brasil). A aplicação do test t pareado aos resultados obtidos, no nível de confiança de 95%, mostrou não haver diferença significativa entre o método proposto e a digestão assistida por microondas.

A method has been developed for the determination of lead in wine by electrothermal atomic absorption spectrometry without any sample preparation and calibration against aqueous standards, using 7.5 microg Pd as a chemical modifier. The results obtained for seven wines using the proposed method and an acid digestion procedure did not show any significant difference using a Student's t-test. Atomization in a transversally heated filter atomizer (THFA) was compared with atomization in a conventional transversally heated platform furnace. The former provided a 2.6-fold higher sensitivity, improving the characteristic mass from 34 to 12 pg and a 1.6-fold better limit of detection (0.3 microg L(-1) compared to 0.5 microg L(-1)) for aqueous solutions using the same injection volume of 20 microL. However, the average precision, expressed as the relative standard deviation for the determination of lead in wine under routine conditions was improved from 4.6% with platform atomization to 0.6% in the THFA. The lead content found in seven arbitrarily chosen white and red wines, five from Brazil, one from Chile and one from Spain, ranged from 6 to 60 microg L(-1) Pb with an average content of 11.4 microg L(-1) Pb for the wines from South America.

In this paper, we proposed a procedure for the determination of iron(II) and total iron in wine samples employing molecular absorption spectrophotometry. The ligand used is 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) and the chromogenic reaction in absence or presence of ascorbic acid (reducing agent) allows the determination of iron(II) or total iron, respectively. The optimization step was performed using a multivariate technique (Box Behnken design) involving the factors pH, acid ascorbic concentration and reaction time. The method allows the determination of iron(II) and iron(III) in wine samples, with limits of detection and quantification 0.22 and 0.72 microg L(-1), respectively. The precision expressed as relative standard deviation (R.S.D.) was 1.43 and 0.56% (both, n=11) for content of iron(II) in wine samples of 1.68 and 4.65 mg L(-1), and 1.66 and 0.87% (both, n=11) for content of total iron in wine samples of 1.72 and 5.48 mg L(-1). This method was applied for determination of iron(II) and total iron in six different wine samples. In these, the iron(II) content varied from 0.76 to 4.65 mg L(-1) and from 1.01 to 5.48 mg L(-1) for total iron. The results obtained in the determination of total iron by Br-PADAP method were compared with those that were performed after complete acid digestion in open system and determination of total iron employing FAAS. The method of regression linear was used for comparison of these results and demonstrated that there is no significant difference between the results obtained with these two procedures.

The present paper describes fundamentals, advantages and limitations of the Box-Behnken design (BBD) for the optimization of analytical methods. It establishes also a comparison between this design and composite central, three-level full factorial and Doehlert designs. A detailed study on factors and responses involved during the optimization of analytical systems is also presented. Functions developed for calculation of multiple responses are discussed, including the desirability function, which was proposed by Derringer and Suich in 1980. Concept and evaluation of robustness of analytical methods are also discussed. Finally, descriptions of applications of this technique for optimization of analytical methods are presented.

The present paper describes the development of a microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry (FAAS). The optimization step was performed using a full factorial design (2(3)) involving the factors: composition of the acid mixture (CMA), microwave power (MP) and radiation time (RT). The experiments of this factorial were carried out using a certified reference material of tea GBW 07605 furnished by National Research Centre for Certified Reference Materials, China, being the metal recoveries considered as response. The relative standard deviations of the method were found below 8% for the three elements. The procedure proposed was used for the determination of copper, zinc and nickel in several samples of tea from Turkey. For 10 tea samples analyzed, the concentration achieved for copper, zinc and nickel varied at 6.4-13.1, 7.0-16.5 and 3.1-5.7 (mu g g(-1)), respectively. (c) 2007 Elsevier B.V All rights reserved.

In the present study, we investigated the role of 5-HT(3) and 5-HT(2C) receptors located within the medial amygdala (MeA) in the control of water and salt intake in sodium-depleted rats. Pharmacological activation of 5-HT(3) receptors located in the medial amygdala by the selective 5-HT(3) receptor agonist m-CPBG significantly reduced salt intake in sodium-depleted rats, an effect that is reverted by pretreatment with the selective 5-HT(3) receptor antagonist ondansetron. In addition, the injection of ondansetron alone into the medial amygdala had no effect on salt intake in sodium-depleted and in sodium-repleted rats. Pharmacological stimulation of 5-HT(2C) receptors located in the medial amygdala by the selective 5-HT(2C) receptor agonist m-CPP failed to modify salt intake in sodium-depleted rats, whereas the blockade of these receptors by the selective 5-HT(2C) receptor antagonist SDZ SER 082 significantly reduced salt intake in this same group of animals. These results lead to the conclusion that the pharmacological activation of 5-HT(3) receptors located within the MeA inhibits salt intake in sodium-depleted rats and that, in this same brain region, the functional integrity of 5-HT(2C) receptors is required to achieve the full expression of sodium appetite in sodium-depleted rats.

Lead is recognized worldwide as a poisonous metal. Thus, the determination of this element is often required in environmental, biological, food and geological samples. However, these analyses are difficult because such samples contain relatively low concentrations of lead, which fall below the detection limit of conventional analytical techniques such as flame atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. Several preconcentration procedures to determine lead have therefore been devised, involving separation techniques such as liquid-liquid extraction, solid phase extraction, coprecipitation and cloud point extraction. Citing 160 references, this paper offers a critical review of preconcentration procedures for determining lead using spectroanalytical techniques.