In this study, the elemental composition of nine medicinal plants and phytomedicines was evaluated by using axial view inductively coupled plasma optical emission spectrometry (ICP OES) after three digestion procedures: dry ashing (DA) and two wet digestions with a mineral acid (HNO3/H2O2) mixture on a conventional hot plate (CD), besides microwave digestion (MW). Accuracy was assessed from spinach leaves (CRM 1570a) and recovery values were in the range of 82 to 113.8%. Precisions, such as relative standard deviation (RSD), below 10% were reached. The MW procedure was preferred for its accuracy (recovery values of 94 to 102%), reduced contamination, increase in the efficiency of the decomposition process, lower residual acidity and reduced time required for digestion. The concentrations of analytes in the samples (minimum-maximum in μg g-1) were: Ca (100.71-462.20), Co (0.54-0.85), Cu (0.32-7.82), Fe (2.74-18.03), Mg (18.40-521.28), Mn (0.17-55.14), Ni (0.56-1.25) and Zn (2.96-20.92). The levels of Al, Ba, Cd, Cr, Mo, Pb, Se and V in all investigated samples were found to be below the limit of detection of ICP OES. The multielement analysis by ICP OES showed that the method is simple, fast and reliable for the multielement determination in medicinal plants and phytomedicines.

Neste trabalho, foi avaliada a composição mineral da farinha de trigo consumida no Brasil. Na etapa de amostragem foram coletadas 54 amostras em 15 cidades, incluindo as principais cidades brasileiras como: São Paulo, Rio de Janeiro, Salvador, Porto Alegre, Recife e outras. Os elementos determinados foram: cálcio, cobre, magnésio, manganês, ferro, fósforo, potássio e zinco. As amostras foram digeridas usando acido nítrico e peróxido de hidrogênio em sistema aberto. A técnica analítica empregada foi a espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). A validação do método (incluindo digestão e determinação) foi confirmada usando um material de referência certificado de farinha de trigo fornecido pelo National Institute of Standards & Technology (NIST). Considerando as 54 amostras analisadas, os resultados demonstraram que os macronutrientes: cálcio, magnésio, potássio e fósforo encontram-se em média de 0,27; 0,35; 1,71 e 1,92 mg g-1, com variação da concentração de 0,11-1,96; 0,19-0,51; 0,76-3,16 e 0,81-7,15 mg g-1, respectivamente. Os micronutrientes: cobre, ferro, manganês e zinco encontram-se em média de 1,84; 37,82; 8,25 e 9,41 µg g-1, com a variação de concentração de 1,00-2,80; 10,46-146,58; 3,89-14,74 e 5,07-13,93 µg g-1, respectivamente. Os resultados foram também avaliados usando as técnicas de análise multivariadas: análise de componente principal (PCA) e análise de agrupamento hierárquico (HCA).

In the present paper, the mineral composition of wheat flour consumed in Brazil was evaluated. In the sampling step 54 samples were collected in 15 cities, including principal Brazilian cities such as: São Paulo, Rio de Janeiro, Salvador, Porto Alegre, Recife and others. The elements determinate were: calcium, copper, magnesium, manganese, iron, phosphorus, potassium and zinc. The samples were digested using nitric acid and hydrogen peroxide in open system. The analytical technique employed was Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). The method validation (including digestion and determination) was performed using a certified reference material of wheat flour furnished by National Institute of Standards & Technology (NIST). Considering the 54 samples analyzed, the results demonstrated that the macronutrients: calcium, magnesium, potassium and phosphorus have average contents of 0.27, 0.35, 1.71 and 1.92 mg g-1, for concentration ranges of 0.11-1.96, 0.19-0.51, 0.76-3.16 and 0.81-7.15 mg g-1, respectively. The micronutrients: copper, iron, manganese and zinc have average contents of 1.84, 37.8, 8.2 and 9.4 µg g-1, for concentration ranges of 1.00-2.80, 10.5-146.6, 3.9-14.7 and 5.1-13.9 µg g-1, respectively. The results were also evaluated using the multivariate analysis techniques: principal component analysis (PCA) and hierarchical cluster analysis (HCA).

Neste trabalho a otimização de um procedimento rápido e de baixo custo para digestão ácida de feijão foi desenvolvida. Elementos essenciais (Ca, Cu, Fe, K, Mg, Mn, Ni, P, Zn) e não essenciais (Al, Ba, Sr) foram determinados por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). Foi utilizado planejamento fatorial de dois níveis fracionário com cinco fatores (volumes de HNO3 e H2O2, tempo, temperatura do bloco e tamanho de partícula). O fator temperatura foi o parâmetro mais importante e o planejamento Doehlert foi aplicado para determinar as condições ótimas, que foram obtidas quando se utiliza 3,5 mL de HNO3 concentrado e o tempo de 45 min. A exatidão foi demonstrada usando um material de referência certificado (folhas de espinafre NIST 1570a) e método oficial recomendado. Os resultados obtidos para todos os analitos foram concordantes com os valores certificados de acordo com o teste-t pareado para um nível de confiança de 95%.

In this work, the optimization of a fast and inexpensive acid wet digestion procedure for beans was developed. Essential (Ca, Cu, Fe, K, Mg, Mn, Ni, P, Zn) and non-essential (Al, Ba, Sr) elements were determined in beans degestates by inductively coupled plasma optical emission spectrometry (ICP OES). Experimental designs for five factors (HNO3 and H2O2 volume, digestion time, block temperature and particle size) were used for optimization of the digestion procedure, adopting a factorial experiment with 2(5-1) design. The factor block temperature was found to be the most important parameter and Doehlert designs were applied in order to determine the optimum conditions. Decomposition conditions were attained using 3.5 mL of concentrated HNO3 and lasts 45 min. The accuracy of the results was demonstrated using one certified reference material (spinach leaves NIST 1570a) and comparison with recommended official method. A paired t-test showed a good agreement for all analytes at 95% confidence values.

No presente trabalho foram avaliados os processos sortivos dos íons Cd2+ e Pb2+ em carne bovina em pH 6. Uma válvula de seleção de 8 canais foi utilizada para a mecanização do preparo das amostras e as concentrações de cádmio e chumbo foram determinadas por ICP-OES. Observou-se alta retenção (> 80%, m/m) dos íons Cd2+ e Pb2+ em carne fresca ou putrefata, indicando os riscos associados ao consumo de carne inadequadamente abatida, manipulada, estocada e/ou comercializada. Ácido acético a 1% (v/v) disponibilizou 70% do cádmio inicialmente adsorvido nas amostras de carne, revelando que práticas culinárias podem influenciar na sorção dos contaminantes.

The metal sorption capacity in fresh and rotten red meat was evaluated for Cd2+ and Pb2+ ions at pH 6 and the process involved in the studied metal retention was discussed. For the experimental set, an eight channels multi-port selection valve was employed to mechanise the sample preparation. The cadmium and lead concentrations were determined by ICP-OES. A high retention (> 80%, m/m) of Cd2+ and Pb2+ ions, in fresh and rotten bovine muscle was found, indicating the potential contamination risks related to the consumption of meat submitted to inappropriate conditions of abattoir, handling, storage and commercialisation. Seventy per cent of the cadmium was released with the immersion of meat in acetic acid at 1% (v/v), revealing that cookery practices may act on contaminant sorptive processes in meat structure.

Os materiais de controle de qualidade (QCM) têm sido usados rotineiramente no trabalho de laboratório, para preencher a lacuna entre a necessidade e disponibilidade de materiais de referência certificados (CRM). Os QCMs possuem custos relativamente baixos, quando comparados aos materiais de referência certificados (CRMs), sendo uma alternativa viável para a implementação de um sistema de controle de qualidade em laboratórios de várias áreas. Este trabalho descreve a produção de um QCM para determinação de metais em sedimentos estuarinos e os resultados de um exercício interlaboratorial. Estudos de homogeneidade e estabilidade foram realizados, e análises de variância foram aplicadas aos dados. As concentrações de Co, Cu, Cr, Ni, Mn, Pb e Zn, dentro e entre recipientes não foram significativamente diferentes. As condições de armazenagem e temperatura não promoveram variação nos resultados. O QCM produzido foi considerado estável e homogêneo, e pode ser utilizado em cartas de controle de qualidade, avaliação da reprodutibilidade e exercícios interlaboratoriais.

Quality Control Materials (QCM) have being used routinely in daily laboratory work as a tool to fill the gap between need and availability of Certified Reference Materials (CRM). The QCM are a low-cost alternative to CRMs, and they are in high demand, especially, for the implementation of quality control systems in laboratories of several areas. This paper describes the preparation of a QCM for the determination of trace metals in estuarine sediments and the results of an interlaboratory exercise. Homogeneity and stability studies were performed and analysis of variance was carried out with the results. No statistical significant differences were observed in the concentrations of Co, Cr, Cu, Mn, Pb and Zn between- or within bottle results. Neither the storage nor temperature affected the results. Therefore, the QCM produced is considered homogeneous and stable and can be used for statistical control charts, evaluation of reproducibility and interlaboratory exercises.

The use of factorial design was evaluated for optimization of focused-microwave-assisted digestion of bean samples. Calcium, Fe, Mg, Mn and Zn percentual recoveries were determined in digestates after focused-microwave-assisted digestion according to factorial design procedures. A cavity microwave digestion was carried out to certify the elemental compositions obtained. The accuracy was checked using a standard reference material, the NIST SRM 8433 - Corn Bran. Results are in agreement with certified values at the 95% confidence limit when the Student t-test was used. Volumes of nitric and sulfuric acid, temperature, and the interplay between HNO3 and H2SO4 initial volumes were significant variables according to P-values in the analysis of variance (ANOVA).

Dois procedimentos foram comparados para separação e pré-concentração de traços de cobre, zinco e manganês em amostras salinas. Os métodos basearam-se na adsorção dos íons metálicos sobre duas fases sólidas obtidas por impregnação de uma resina não-iônica Amberlite XAD-7 e uma resina aniônica Dowex 1X8-50 com o reagente vermelho de alizarina S (ARS), ácido nítrico foi utilizado para re-extrair os cátions das fases sólidas, os quais foram determinados por FAAS. Para o sistema Amberlite XAD-7/ARS, Mn, Cu e Zn foram quantitativamente retidos, na faixa de pH de 8,5 a 10,0, para uma massa de 0,50 g da fase sólida, após 5 min de agitação e uma massa total de até 200 µg de cada metal. Os elementos foram eluídos com 5 mL de HNO3 3 mol L-1, com recuperação ³ 95%, obtendo-se fator de pré-concentração de até 50 vezes para Zn e de 10 vezes para Mn e Cu. Para o sistema Dowex 1X8-50/ARS, Cu, Mn e Zn foram quantitativamente retidos, na faixa de pH de 8,1 a 9,0 e Zn em pH 8,1, usando uma massa de 0,75 g da fase sólida, após 90 min de agitação e uma massa total de até 50 µg de cada metal. Os elementos foram eluídos com 20 mL de HNO3 2 mol L-1, obtendo-se fator de pré-concentração de até 5 vezes para Cu e Zn. A precisão dos procedimentos foi estabelecida pela medida de 10 replicatas com 250 µg L-1 de cada íon e os desvios padrão relativos foram de 0,2% (Cu), 0,4% (Mn), e 0,4% (Zn), para ARS-XAD7 e 0,3% (Cu), 0,5% (Mn), e 0,3% (Zn), para ARS-Dowex. Os procedimentos propostos foram aplicados na determinação de Mn, Cu e Zn em solução fisiológica e água do mar da cidade de Salvador/BA. Testes de recuperação com adição de 5 mg dos metais às amostras revelaram eficiência no que diz respeito à exatidão e a precisão dos procedimentos propostos, com recuperação quantitativa (³ 95%).

Two procedures have been proposed and compared for separation and preconcentration of trace amounts of manganese, copper, and zinc in saline samples. The procedures are based in the use of Amberlite XAD-7 and an anion-exchanger Dowex 1X8-50 loaded with Alizarin Red S (ARS). In order to obtain quantitative recoveries of metal ions, various experimental parameters such as pH, shaking time, sample volume, amounts of solid phase, effects of concomitants, capacity and cations desorptions from solid phases were optimized. For Amberlite XAD-7 impregnated with ARS (XAD 7-ARS), Mn, Cu, and Zn were quantitatively retained, in the pH range 8.5-10.0, by using 0.50 g of solid phase, stirring time of 5 min and a total mass up to 200 µg of each cation. The sorbed elements were subsequently eluted with 5 mL of 3 mol L-1 HNO3, with recovering over 95%, and a fifty-fold preconcentration factor for Zn and a ten-fold preconcentration factor for Mn and Cu were obtained. For Dowex 1X8-50 impregnated with ARS (Dowex-ARS), Cu and Mn were quantitatively retained in the pH range 8.1 to 9.0, and Zn pH 8.1, by using 0.75 g of solid phase, 90 min of stirring time and a total mass up to 50 µg of each cation. The sorbed elements were subsequently eluted with 20 mL of 2 mol L-1 HNO3, and a five-fold preconcentration factor to Cu and Zn was obtained. The precision of the procedure was determined by running 10 replicate samples, each one containing 250 µg L-1 of each element and the relative standard deviations were 0.2% (Cu), 0.4% (Mn), and 0.4% (Zn), to XAD 7-ARS and 0.3% (Cu), 0.5% (Mn), and 0.3% (Zn), to Dowex-ARS. The procedures were used for determining of Mn, Cu, and Zn in physiological solutions and seawater samples, from Salvador-Bahia. The analyte addition technique was used and the recoveries obtained (³ 95%) revealed that the proposed procedure shows good accuracy and precision.

Um procedimento em batelada é proposto para separação e pré-concentração de cádmio, chumbo, níquel e zinco em amostras de salmoura. O método baseia-se na adsorção dos íons metálicos sobre a fase sólida composta de ditizona co-cristalizada com naftaleno microcristalino, na faixa de pH de 8,5 – 9,1. Ácido nítrico é utilizado para re-extrair os cátions da fase sólida, os quais são determinados por ICP-OES. Vários parâmetros, tais como efeito do pH, do tempo de agitação e da quantidade da fase sólida foram estudados sistematicamente visando otimizar as condições para a determinação de quantidades traço de Cd, Cu, Pb, Ni e Zn em amostras sintéticas de salmoura. Os limites de detecção obtidos, expressos em mg L-1, foram: 44 (Zn), 11 (Ni), 30 (Cd), 47 (Pb) e 11 (Cu). A precisão do procedimento foi estabelecida pela medida de 10 replicatas com 250 μg L-1 de cada íon e os desvios padrão relativos foram de 2,71 % (Cd), 2,15 % (Cu), 1,53 % (Pb), 2,47 % (Ni) e 2,78 % (Zn). A exatidão do procedimento foi confirmada pelo método de adição de analitos e os resultados obtidos indicaram recuperação quantitativa (≥ 95 %).

A procedure for separation and pre-concentration of trace amounts of cadmium, copper, lead, nickel, and zinc in brine samples has been proposed. It is based on the adsorption of metal ions onto dithizone co-crystallized with microcrystalline naphthalene, in the pH range 8.5-9.1. Nitric acid is used to back-extract the cations from the solid phase, which are measured by ICP-OES. Various parameters, such as the effect of pH, stirring time, and amounts of solid phase, have been studied in detail, to optimize the conditions for the determination of trace amounts of Cd, Cu, Pb, Ni and Zn in synthetic brine samples. The limits of detection values expressed in μg L-1 are 44 (Zn), 11 (Ni), 30 (Cd), 47 (Pb) and 11 (Cu). The precision of the procedure was determined by running 10 replicate samples, each one containing 250 μg L-1 of each element and the relative standard deviations were 2.71 % (Cd), 2.15 % (Cu), 1.53 % (Pb), 2.47 % (Ni), and 2.78 % (Zn). The accuracy of the procedure was confirmed by applying the analyte additions method and the results indicated that quantitative recoveries (≥ 95 %) were obtained.

In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorption spectrophotometry (FAAS). In the spectrophotometric determinations were studied pH conditions, reagents addition order, interferences, amount of reagents, linear range and stability of the system. In the techniques of ICP-AES and FAAS were studied the best lines, interferences, sensibility and linear range. The obtained results were compared and the agreement was evaluated among the methods for the determination of the metals of interest.

O presente trabalho descreve o uso de 1-(2-thiazolylazo)-p-cresol (TAC) para separação, preconcentração e determinação de traços de ferro (ng g-1) em sais alcalinos usando a técnica ICP-AES. O método proposto é baseado na extração líquido-líquido do complexo formado entre o cátion ferro(III) e o 1-(2-thiazolylazo)-p-cresol (TAC). Foram estudados parâmetros tais como: quantidade de TAC, efeito de pH, influência do solvente orgânico, mineralização da fase orgânica e re-extração. Os resultados demonstraram que o complexo ferro(III)-TAC, formado na faixa de pH de 4,0 a 10,0, pode ser quantitativamente extraído de soluções salinas, usando como solvente extractor álcool isoamílico, tetracloreto de carbono, clorofórmio ou metil isobutil cetona. A solução para determinação de ferro pode ser obtida por uma re-extração usando soluções de ácido clorídrico 1 mol/L ou ácido nítrico 1 mol/L ou também por uma mineralização da fase orgânica, com uma evaporação do solvente orgânico e digestão do resíduo com ácido nítrico concentrado. O procedimento foi usado para determinação de ferro em amostras de vários sais alcalinos. A técnica da adição padrão foi aplicada e as recuperações obtidas revelaram que o procedimento proposto tem uma boa exatidão.

The present paper describes the use of 1-(2-thiazolylazo)-p-cresol (TAC) for separation, preconcentration and determination of iron traces (ng g-1) in alkaline salts by the ICP-AES technique. The proposed method is based on the liquid-liquid extraction of the complex formed between iron(III) and 1-(2-thiazolylazo)-p-cresol (TAC). Parameters such as: TAC amount, pH effect, influence of the organic solvent on the extraction, back extraction and mineralization of the organic phase were studied. The results show that the iron(III)-TAC complex, formed in the pH range from 4.0 to 10.0, can be quantitatively extracted from saline solutions (up to 30% NaCl) using isoamyl alcohol, carbon tetrachloride, chloroform or methyl isobutyl ketone as extracting solvent. The solution for the iron determination can be obtained by a back extraction using 1 mol/L hydrochloric acid or 1 mol/L nitric acid solutions or also by mineralization of the organic phase, which was accomplished by evaporation of the organic solvent and digestion of the residue with concentrated nitric acid. The procedure was used for iron determination in several alkaline salt samples. The standard addition technique was applied and the recoveries obtained revealed that the proposed procedure has a good accuracy.