Sample preparation of polymers for halogen determination requires special attention because they are difficult to bring into solution and due to the risk of analyte losses when using acid digestion. A method using microwave-induced combustion (MIC) was optimized for accurate determination of halogens in polymeric parts obtained in waste of electrical and electronic equipment. Results were compared with those by using microwave-assisted extraction (MAE) with alkaline solution and microwave-assisted wet digestion (MAWD) using concentrated nitric acid, which are common choices for sample preparation. In this particular case, the MAE method was not suitable and underestimated results were obtained, showing the necessity for the complete digestion. Even with the use of MAWD under high temperature and pressure, incomplete digestion and high acid content were obtained, which were unsuitable for analysis and resulted in poor recovery. Only by using MIC (diluted ammonia as absorbing solution) acceptable recoveries (95 to 104%) and agreement with certified values for the certified reference materials (CRMs) of polymers were obtained. Thus, a suitable method for all halogen to be determined by ion chromatography (IC) or inductively coupled plasma mass spectrometry (ICP-MS), with the exception of F, was obtained in agreement with the requirements by the Restriction of the Use of Certain Hazardous Substances (RoHS) European directive.

A method for digestion of plastics from waste of electrical and electronic equipment (WEEE) was developed using the microwave-assisted wet digestion in single reaction chamber (MAWD-SRC). The determination of As, Cd, Co, Cr, Cu, Ni, Pb, Sb and Zn by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES) was carried out after sample digestion. Mercury was determined by flow-injection cold vapor generation coupled to inductively coupled plasma mass spectrometry (FI-CVG-ICP-MS). Results obtained using MAWD-SRC for sample preparation were compared with those obtained using microwave-assisted wet digestion (MAWD) at high pressure. Acid mixtures (HNO3 or HNO3 + HCl) were evaluated and feasibility for further inorganic contaminants determination by ICP-MS and ICP OES was demonstrated. Sample preparation by MAWD-SRC using HNO3 + HCl mixture resulted in better digestion efficiency in comparison to MAWD. In addition, lower limits of quantification were obtained using MAWD-SRC due to the higher sample mass that can be digested (500 mg). The combination of HNO3 and HCl for digestion showed to be crucial for quantitative recovery of some elements, as Cr and Sb. Agreement with certified values was better than 96%.

A method for digestion of crude oil distillation residues (atmospheric residue, AR and vacuum residue, VR) using microwave-induced combustion (MIC) was developed for simultaneous determination of metals (Ba, Co, Fe, Mg, Mn, Ni and V) and sulfur by inductively coupled plasma optical emission spectrometry (ICP-OES). Samples were wrapped in polyethylene films and combusted using 20 bar of oxygen. Nitric acid solutions were evaluated using 5 min of reflux after combustion. Accuracy was evaluated using certified reference material and comparison with the results obtained by microwave-assisted wet digestion (MAWD). No statistical difference was observed between the certified values and those obtained using MIC as well as between the values obtained using MAWD or MIC. In spite of both methods have been apparently suitable for crude oil digestion, MIC was preferable in view of the possibility of using 3 mol L-1 HNO3 as absorbing solution. Furthermore, it is important to notice that using MIC, C content in digests was lower than 10 mg L-1, preventing interferences in ICP-OES. In addition, the simultaneous digestion of eight samples was possible in less than 30 min and without using concentrated acids and/or longer heating times, making the proposed method well-suited for routine analysis.

In this work, a method using microwave-induced combustion (MIC) was optimized in order to obtain a fast, simple, efficient and greener sample preparation method for coal digestion and further determination of sulfur by inductively coupled plasma optical emission spectrometry (ICP OES). Accuracy was evaluated by comparison of the results with those obtained using elemental analysis by UV-fluorescence, microwave-assisted acid digestion with determination by ICP OES and by analysis of certified reference materials of coal. Some parameters that influence MIC method, such as the type and concentration of absorbing solution, the necessity of using a reflux step as well as the cooling time were carefully optimized. No statistical difference was observed for combustion without reflux followed by 5 min of cooling, in comparison to the reference values obtained by elemental analysis. Complete digestion was obtained with this fast and simple method (total digestion program required only 6 min) and using a diluted acid solution for quantitative recovery. The feasibility of digests for sulfur determination as sulfate by ion chromatography (IC) with conductivity detection was also demonstrated. The possibility of determining other elements, commonly monitored in coals, is another advantage of this high-efficiency digestion method (MIC) combined with the multielemental capacity of ICP OES or IC instruments.

Em virtude das altas taxas de decomposição do material orgânico em regiões tropicais, um dos problemas para a manutenção e sustentabilidade do sistema de plantio direto é a necessidade de produção de grandes quantidades de palha. Com o objetivo de identificar, no sistema de integração agricultura-pecuária, as variações dos atributos físicos do solo e a produtividade de grãos de soja sobre palhada de braquiárias, este trabalho foi conduzido na FEPE-UNESP de Ilha Solteira, SP, e o delineamento experimental utilizado foi o de blocos ao acaso, com nove tratamentos em esquema fatorial (3 x 3), com quatro repetições. Os tratamentos foram constituídos por três espécies de braquiárias e três modalidades de consórcio das braquiárias com o milho. Os atributos físicos foram determinados antes da implantação do projeto de pesquisa, após a colheita do milho consorciado com as forrageiras e depois da colheita da soja. Na safra de verão a cultura da soja foi semeada sobre a palhada dos consórcios de milho com braquiárias, no espaçamento de 0,45 m, com 14 linhas por parcela e área útil correspondente às 4 linhas centrais de 5 m cada uma. Os resultados permitiram concluir que a consorciação e a sequência de culturas proporcionaram aumento na macroporosidade e porosidade total do solo. A Brachiaria brizantha semeada na época de adubação de cobertura do milho e a Brachiaria decumbens, na linha do milho, promoveram maiores valores de produtividade de grãos de soja.

In tropical regions, due to high rates of decomposition of the organic material, one of the problems for the maintenance and no tillage system sustainability is the necessity of production of great quantities of straw. With the objective to identify, in the pasture-agriculture integration system, the variations of soil physical attributes and yield of soybean on brachiaria straw, the present work was conducted at the FEPE-UNESP of Ilha Solteira, SP. The randomized block experimental design was used , with nine treatments in the fatorial scheme 3x3, with four repetitions. The treatments consisted of three species of brachiaria and a consortium of the three types of brachiaria with corn. The physical properties of soil were determined before the installation of the experimente, after the harvest of corn intercropped with forage and after the harvest of soybeans. In summer the soybean crop was sown on the straw of corn and brachiaria spaced 0.45 m, with 14 lines per plot and area for data collection consisting of 4 lines of 5 m each. The results showed that intercropping and sequence of crops provided increase of soil macroporosity and total porosity. Brachiaria brizantha sown at the time of top-dressing of corn and Brachiaria decumbens sown in line promoted higher yields of soybeans.

A determinação de Al, Cd, Co, Cr, Cu, Mg, Mn e Pb em nanotubos de carbono (CNTs) foi realizada por espectrometria de absorção atômica com atomização eletrotérmica e amostragem direta de sólidos (DSS-ET AAS, corretor de fundo com fonte de deutério). Foram avaliados os parâmetros de aquecimento, uso de Pd como modificador químico, possibilidade de calibração com soluções aquosas e massa máxima de amostra. Para comparação dos resultados as amostras foram analisadas por espectrometria de massa com plasma indutivamente acoplado (ICP-MS) e espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) após decomposição por via úmida em sistema de alta pressão assistida por micro-ondas e também por combustão iniciada por micro-ondas. Não foram observadas diferenças significativas entre os resultados obtidos pelo método proposto e pelas outras técnicas. A exatidão também foi avaliada por comparação com resultados de análise por ativação neutrônica (NAA). A calibração foi possível com soluções de referência aquosas. Os sinais de fundo foram sempre inferiores a 0,02 (altura de pico) e o uso de modificador químico não foi necessário. O método proposto possibilitou a determinação de todos os analitos, com menores limites de detecção quando comparados com as outras técnicas.

Metal impurities (Al, Cd, Co, Cr, Cu, Mg, Mn and Pb) were determined in carbon nanotubes (CNTs) by direct solid sampling electrothermal atomic absorption spectrometry (DSS-ET AAS, deuterium lamp background corrector). Parameters as pyrolysis and atomization temperatures, use of Pd as chemical modifier, feasibility of calibration using aqueous standard solutions and maximum sample mass were investigated. Results obtained by the proposed method were compared with those obtained by neutron activation analysis (NAA) and also by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES) after high-pressure microwave assisted wet digestion and microwave-induced combustion methods. No significant differences were observed between the results obtained by DSS-ET AAS, ICP-MS and ICP OES after both digestion methods and also by NAA. Calibration was performed using aqueous standards. Background signals were always lower than 0.02 (peak height) and no chemical modifier was used. The proposed method allowed the determination of all elements in CNTs with lower limits of detection in comparison with other techniques.

Em regiões de clima tropical, com altas taxas de decomposição do material orgânico, uma alternativa para suprir o aporte anual de palha exigido para proporcionar a sustentabilidade do sistema plantio direto é a consorciação de forrageiras com culturas produtoras de grãos. Com o objetivo de identificar, no sistema de integração agricultura-pecuária, a melhor modalidade de consorciação de três espécies de braquiária (Brachiaria brizantha B. decumbens, e B. ruzizienses) com milho outonal (linha, entrelinha e entrelinha na época de adubação de cobertura do milho), foi conduzido o presente trabalho. Foi utilizado o delineamento em blocos ao acaso, no esquema fatorial (3x3), com quatro repetições. Foram avaliadas: massa seca de palha do milho, massa seca da palha de braquiária, massa seca total de palha, massa de 1.000 grãos e produtividade de grãos. Os resultados demonstraram que, quando o foco principal da consorciação de milho com braquiária for produtividade de grãos e o foco secundário for formação de palha, a utilização da Brachiaria ruzizienses semeada na época de adubação de cobertura do milho proporcionou maiores valores de produtividade de grãos. Todos os tratamentos produziram quantidade de palha suficiente para a manutenção da estabilidade do sistema de semeadura direta.

In tropical regions with high rates of organic material decomposition, an alternative to supply the annual amount of straw required to provide the no tillage system sustainability is the use of intercrop of forage plants with grain crop. The present work was conducted with the objective of identify the best intercrop modality of three species of brachiaria (Brachiaria brizantha, B. decumbens and B. ruziziensis) with fall maize (row, interrow, interrow at the moment of maize coverage fertilization) in the pasture-agriculture integration system. It was used a randomized block design in a factorial scheme (3x3) with four repetitions evaluating dry weight of maize straw, dry matter of pasture straw, total dry weight of straw, 1000 grain weight and grain yield. The results showed that when the main focus of intercropping maize with pasture for grain yield and the secondary focus is the formation of straw, the use of Brachiaria ruziziensis sown at the time of maize manuring led to the highest grain yield. All treatments produced sufficient quantity of straw to maintain the stability of no tillage.

OBJETIVO: Diante de um paciente portador de hiperparatiroidismo primário com indicação de tratamento cirúrgico, a localização pré-operatória da paratiroide é de fundamental importância para definir a melhor abordagem cirúrgica. MATERIAIS E MÉTODOS: A realização adicional de imagens SPECT e da cintilografia com 99mTc durante a cintilografia das paratiroides com Setamibi não é rotina em nosso meio, sendo comum a aquisição apenas das imagens planas − precoce (15 minutos) e tardia (2 horas). RESULTADOS: Na nossa experiência, tem-se percebido que a realização do protocolo completo contribui de maneira decisiva na sensibilidade da localização pré-operatória da paratiroide. CONCLUSÃO: A aplicação completa de todos os métodos cintilográficos disponíveis (SPECT e 99mTc) e a análise cuidadosa das imagens em um contexto multidisciplinar podem aumentar a acurácia da cintilografia das paratiroides.

OBJECTIVE: In patients with primary hyperparathyroidism, candidates for surgical intervention, the parathyroid pre-operative localization is of fundamental importance in planning the appropriate surgical approach. MATERIALS AND METHODS: The additional acquisition of SPECT and Technetium-99m images, during parathyroid scintigraphy with Sestamibi, is not common practice. Usually, only planar image acquisition, 15 minutes prior and 2 hours after radiopharmaceutical administration, is performed. RESULTS: In our experience, the complete protocol in parathyroid scintigraphy increases the accuracy of pre-operative parathyroid localization. CONCLUSION: The complete utilization of all available nuclear medicine methods (SPECT e 99mTc) and image interpretation in a multidisciplinary context can improve the accuracy of parathyroid scintigraphy.