ABSTRACT Determination of potential contaminants elements in food packing films arising from contact with acidic aqueous foods was undertaken by inductively coupled plasma optical emission spectrometry (ICP OES) in accordance with DIN EN 1186-1. Test sections from plastic films were totally immersed in 3% w/v CH3COOH used as the food simulant. Testing was conducted under three conditions: (1) 10 days at 40 ºC; (2) 30 min at 70 ºC and 10 days at 40 ºC; and (3) 30 min at 100 ºC and 10 days at 40 ºC. These time and temperature conditions were considered to be the most severe situations likely to be encountered in practice. Several different containers were investigated, including a borosilicate glass beaker, a glass bottle used for food canning, as well as one of polystyrene. The glass bottle was selected for testing treatments according to procedure (3) and a polystyrene one was chosen for use with procedures (1) and (2). Limits of quantitation were adequate for the determination of Ag, B, Ba, Cd, Cr, Cu, Pb, Sb, Sn and Zn by solution nebulization ICP OES and As by chemical vapor generation (CVG-ICP OES). Results for the analysis of AccuStandard certified reference materials as well as spike recoveries show good agreement with expected concentrations, demonstrating the accuracy and precision of the determinations. Eleven samples of food packing material were analyzed. The lead was present in the range 4.8 - 85.3 µg L-1 in 10 of 11 evaluated packing material, showing the importance of quality control measures.

ABSTRACT Twenty-seven bottled mineral waters from local markets in Curitiba, State of Paraná, Brazil were analyzed for a number of constituents, including: pH, conductivity, total dissolved solids, hardness, HCO3 - and CO 3 2-, as well as Ca2+, Mg2+, Na+, K+, NH4 + , F-, Cl-, NO3 -, NO2 - and SO4 2- by ion chromatography (IC); Al, Ba, Cd, Cr, Cu, Fe, Li, Mn, Ni, Sr, V and Zn by inductively coupled plasma optical emission spectrometry (ICP OES); Hg by cold vapor generation-ICP OES and As, Pb, Sb and Se by ICP-mass spectrometry (ICP-MS). The obtained limits of quantitation (LOQ) were adequate for the determination of all analytes using the various analytical techniques. Results for the analysis of AccuStandard certified reference materials QCS-01-5, QCS-02-R1-5 and TCLP-02-1 as well as spike recoveries to samples show acceptable values, within 90-111 % of expected concentrations with relative standard deviations below 10 %, demonstrating the accuracy of the determinations. Both NO2 - and NO 3 - were above the maximum limits set by Brazilian legislation in two samples, indicating a microbiological contamination. One imported sample presented As (6.1 ± 0.2 µg L-1) near the maximum limit (10 µg L-1) while all other elements of interest were below the values specified by Brazilian legislation. Principal component analysis revealed that four imported samples and one from the Minas Gerais State have the highest mineral concentrations.

A presença de alguns elementos inorgânicos no biodiesel pode comprometer a qualidade do combustível e aumentar a emissão de poluentes. Neste contexto, este artigo descreve um procedimento para o preparo das amostras de biodiesel utilizando high pressure asher (HPA) para a determinação de Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, Sr e Zn, em biodiesel de soja, girassol, sebo bovino, algodão e mamona, por espectrometria de emissao optica com plasma indutivamente acoplado (ICP OES). Os parâmetros de digestão do HPA foram otimizados para digerir 1,5 g de biodiesel, com HNO3 e H2O2, a temperatura de 300 °C e pressão de 435 psi, considerando o fator de diluição da amostra, os sólidos dissolvidos e a acidez da amostra para as determinações por ICP OES. A concentração dos elementos determinados nos biodieseis acima listados foram calculados utilizando o método de adição de padrão. Os limites de detecção na faixa de 0,05-0,7 mg kg- 1 foram adequados para atender os parâmetros de qualidade de biodiesel, seguindo a política de governo e legislações em todo o mundo. Portanto, o procedimento proposto mostrou-se eficiente para eliminar as principais interferências orgânicas presentes em amostras à base de óleo, permitindo uma condição analítica rápida, precisa, livre de interferências e robusta para a caracterização do biodiesel.

The presence of some inorganic elements in biodiesel can compromise the fuel quality and enhance the emission of pollutants. In this context, a new procedure for biodiesel sample preparation using a high pressure asher (HPA) is presented, aiming the determination of Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, Sr, and Zn, in soybean, sunflower, animal fat, cotton and castor oil, by inductively coupled plasma optical emission spectrometry (ICP OES). The digestion conditions of the HPA were optimize to digest 1.5 g of biodiesel, with HNO3 and H2O2, at a temperature of 300 °C and pressure of 435 psi, which considered the sample dilution factor, the total solids in solution and the acidity for ICP OES determinations. Analytes concentrations in these biodiesels were calculated using standard addition method. Detection limits from 0.05 to 0.7 mg kg- 1 were suitable to attend biodiesel quality parameters, government policy and legislations worldwide. Therefore, the proposed procedure proved to be efficient to eliminate the major organic interferences typically present in oil based samples allowing a fast, precise, interference-free and robust analytical condition for biodiesel characterization.

An on-line method for Cd and Pb pre-concentration and simultaneous determination in acid digested seafood by inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The on-line pre-concentration was based on the complex formation of the analytes with the ammonium salt of O,O-diethyldithiophosphate (DDTP) and using the Amberlite XAD-4 resin as a solid support in a homemade column. Different conditions of the flow injection system, such as solutions flow rates, nebulizer pressure and eluent concentration were optimized. Three certified reference materials of lobster hepatopancreas, dogfish liver and fish protein, three samples of fish muscle and three samples of shrimp were digested with HNO3, H2O2 and H2SO4 in a microwave system under reflux. DDTP was added in the solutions obtained, and the mixture was injected in the FI system. Calibration curves for Cd and Pb were obtained using the standard solutions in the concentration range 0.05-0.5 µg mL-1 in the digestion medium, submitted to the same pre-concentration procedure. The quantification limits (3.3 x LOD) for 5 min of pre-concentration time were 0.005 mg kg-1 Cd2+ and 0.1 mg kg-1 Pb2+ in the sample of fish or shrimp in natura, considering 1.0 g of the sample in a final volume of 50 mL. The agreement of the obtained concentrations with the certified ones (Student t-test, 95% confidence) and the recoveries of spiked real samples, from 90 to 120%, demonstrated good accuracy. Precision was also adequate, with relative standard deviations from 2 to 13%. The method was accurate, precise and certainly could be applied to the digested samples of different natures.

A method for evaluating inorganic constituents in the grass by ICP OES is proposed. The samples were digested with nitric acid plus hydrogen peroxide in a microwave system. Seventeen samples were collected in the metropolitan area of Curitiba and Castro in the Paraná State, Brazil. The following elements were studied: Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se and Zn. The linear coefficients of the curves were higher than 0.999 and the precision, expressed as the relative standard deviation, which was below 10%, being considered adequate. The accuracy was validated by using the recovery test (recoveries from 80 to 107%) and by the analysis of botanical certified materials. For one sample, two other digestion procedures, using two different mixtures of nitric and hydrochloric acids, produced results in agreement with the adopted procedure. Eleven out of the twenty studied elements could be quantified in real samples. High concentrations of Ca, K, Mg and P, the essential elements for bovines and other animals, were found. The results were evaluated using the principal component analysis that gathered the samples in three groups, according to the areas where the plants were grown.

O presente trabalho apresenta um estudo comparativo das técnicas ICP-MS e ICP OES com configuração axial e também de dois métodos diferentes de tratamento das amostras, ou seja, por dissolução total com e sem separação do cobre por eletrodeposição, para as determinações de As, Fe, Mn, Pb, Sb e Sn em amostras de cobre eletrolítico. Amostras comerciais e industriais foram dissolvidas com HNO3 5% v/v e o cobre foi eletrodepositado em meio de HNO3 (1,4% v/v) e H2SO4 (2,0% v/v). Verificou-se que a separação do cobre foi eficiente, contudo se constatou contaminação de Fe e Sn durante o processo de eletrodeposição. As determinações foram realizadas utilizando-se um ICP OES Axial Varian (Vista Pro) e um ICP-MS Perkin Elmer (Elan Sciex 6000). Foi aplicada a calibração externa, com soluções padrão contendo ou não cobre na concentração equivalente à da amostra. Os limites de detecção (3s, n=10) para a técnica de ICP OES foram bastante semelhantes na presença ou não do cobre). Já usando ICP-MS, os limites foram melhores na ausência do cobre. Com o objetivo de estabelecer o nível de significância entre as técnicas de quantificação, ou seja, entre ICP OES e ICP-MS,foi aplicado o teste t emparelhado, que demonstrou, para um nível de confiança de 95%, não haver diferença significativa, tanto para as soluções sem ou com cobre. Os resultados obtidos no presente trabalho demonstraram que as técnicas ICP-MS e ICP OES fornecem resultados similares em determinadas faixas de concentração dos analitos, podendo ambas serem utilizadas, no controle de qualidade do cobre eletrolítico. Contudo, a técnica ICP-MS foi superior em termos de limite de detecção.

The performance of axial view ICP OES and ICP-MS techniques were compared through the determination of As, Fe, Mn, Pb, Sb and Sn in electrolytic copper. Samples were prepared by two procedures: 1. Total dissolution with 5 % v/v HNO3 and 2. Dissolution with 1.4 % v/v HNO3 plus 2.0 % v/v H2SO4, followed by separation of the Cu by electrodeposition. The methods were applied for the analysis of standard copper solutions, using calibration against aqueous solutions with or without the addition of Cu. The results obtained by the two techniques were similar, but the separation of Cu from the sample matrix proved to be more adequate for practical reasons.

O presente trabalho descreve um método para determinação de arsênio e selênio em café solúvel por espectrometria de emissão atômica com plasma acoplado a geração de hidretos, com o objetivo de atender aos limites estabelecidos pela legislação Brasileira de alimentos. Digestões das amostras foram realizadas com ácido nítrico e peróxido de hidrogênio em sistema de microondas focalizadas. O excesso de ácido nítrico foi eliminado através de aquecimento lento e o selênio (VI) foi reduzido a selênio (IV) através de tratamento com ácido clorídrico 6 mol/L e aquecimento a 90° C em sistema de refluxo. A influência da acidez na sensibilidade foi investigada, sendo o meio mais estável a concentração de ácido clorídrico de 6 mol/L. Os limites de determinação foram de 2.0 mig/L para o As e 1.0 mig/L para o Se. Os resultados das amostras enriquecidas demonstram a precisão e exatidão do método proposto.

A method for the evaluation of arsenic and selenium in soluble coffee by inductively coupled plasma atomic emission spectrometry with continuous hydride generation to attend the Brazilian food legislation is described. Samples were digested with nitric acid and hydrogen peroxide in a focused microwave system. Slow heating eliminated nitric acid and selenium (VI) was reduced to selenium (IV) by addition of 6 mol/L hydrochloric acid and heating at 90° C under a reflux system. The influence of sample acidity on sensitivity was investigated. Hydrochloric acid 6 mol/L was the most suitable reaction medium. Practical detection limits of 2.0mug/L for As and 1.0mu g/L for Se were achieved and attended the Brazilian food legislation. The results of recoveries on spiked samples demonstrate the reliability and accuracy of the procedure.