This study compares the techniques cold vapour atomic fluorescence spectrometry (CV-AFS) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of Hg in biological samples (hepatic tissue from marine tetrapods). Acid digestions were performed for the samples and aliquots of them were analysed by ICP-MS and CV-AFS. To minimize the Hg memory effect in its determination by ICP-MS, gold (200 µg L-1 in 5% v v-1 HCl) was added to the sample digests. The detection limits were 0.02 mg kg-1 for ICP-MS and 0.01 mg kg-1 for CV-AFS. Accuracy was assessed by the calculation of the recovery obtained from TORT-3 (lobster hepatopancreas) certified reference material analysis. Accurate results were obtained for both CV-AFS and ICP-MS. The comparison of the results obtained for hepatic tissue with and without lyophilization showed a significant difference among them (at 95% of confidence level), evidencing losses of Hg in the lyophilization process.

The acute toxicity of copper and cadmium in Oreochromis niloticus was evaluated through a 96 h static assay. Precipitation of Cu and co-precipitation of Cd in the presence of Cu were noted, being indicative of differences in nominal and actual concentrations of metals. Under these conditions, LC50-96h was determined as 3.53 mg L-1Cu, 20.1 mg L-1 Cd and 1.36 mg L-1 (Cu + Cd). Besides the quantitative determinations of total dissolved metals in water, considerations on Cd/Cu interactions in aquatic media were presented, allowing the assessment for metals speciation. Data revealed that alkalinity, hardness, dissolved organic carbon and formation of inorganic complexes reduce metal availabilities, mainly in relation to Cu. In spite of this, the LC50 for Cd was significantly reduced in the presence of Cu, matching environmental realistic values. Based on simulated fate of metals, hardness may impair a reduction of 18 and 2% in metal activities, respectively to Cu and Cd.

An analytical method to determine tin concentrations in natural samples, by coupling atomic fluorescence spectrometry, hydride generation and flow injection system was developed. The sample digestion procedure and the conditions of hydride generation were fully optimized. The best conditions for the generation of SnH4 were obtained with NaBH4 4% (m v-1) and HCl 0.6 mol L-1. The optimized flow rates were 1.2 mL min-1 for sample, 1.2 mL min-1 for HCl and 1.6 mL min-1 for NaBH4 solution. The sample volume was 500 µL. The best acid volume for digestion of solid samples was stablished to be 3 mL HNO3 + 1 mL HCl. The accuracy of the method was established by the analysis of certified reference materials and by comparative determinations, using inductively coupled optical emission spectrometry. The approach developed was shown to offer a robust method with excellent accuracy and precision for the determination of Sn in environmental samples. Finally, the method was applied to analyse the soil, sediment and water samples, collected in area under anthropogenic activities: processing area of cassiterite in Corumbataí/SP. The obtained data indicated that there was alteration in the natural quality of the environment as a result of the activities developed in that site

Foi avaliada a bioconcentração de cádmio e chumbo pelo caranguejo fluvial Trichodactylus fluviatilis. Trinta animais foram expostos a 200 µg L-1 de cádmio e chumbo por 7, 14 e 21 dias. Após dissecação e digestão nitro-perclórica, os metais foram determinados nas brânquias, hepatopâncreas e músculo por espectrometria de emissão óptica com plasma acoplado indutivamente. O chumbo foi detectado apenas nas brânquias, sem diferenças significativas entre diferentes períodos de exposição. O cádmio foi encontrado em todos os tecidos após exposição. Diferenças significativas entre as concentrações de cádmio em animais expostos por diferentes períodos sugerem um processo de acumulação, com concentração estabilizada após 14 dias. Usando um procedimento de extração em fase sólida com Saccharomyces cerevisae e com o objetivo de avaliar a transferência e estocagem de cádmio nos tecidos, foi realizado o fracionamento de cádmio na forma livre (ou lábil) e cádmio-proteína (possivelmente metalotioneína) (Cd-P) em animais expostos a 200 µg L-1 de cádmio por 21 dias. A determinação de cádmio livre e Cd-P nos tecidos mostrou que nas brânquias o metal foi encontrado principalmente na forma livre, enquanto que no hepatopâncreas o metal foi encontrado principalmente ligado à proteína. Pode-se inferir que, absorvido através das brânquias, o cádmio foi transferido e estocado no hepatopâncreas dos animais.

The bioconcentration of cadmium and lead by the freshwater crab Trichodactylusfluviatilis was evaluated. Thirty animals were exposed to 200 µg L-1 of cadmium and lead for 7, 14 and 21 days. Both metals were determined in gills, hepatopancreas and muscle after dissection and digestion by inductively coupled plasma optical emission spectrometry. Lead was detected only in gills, but without significant difference among different exposure periods. Cadmium was found in all tissues after exposure. Significant differences among cadmium concentrations in animals exposed for different periods suggest an accumulation process, with concentration stabilized after 14 days. Fractionation of free (or labile) cadmium and cadmium protein (possibly metallothionein) (Cd-P) in gills and hepatopancreas were carried out to assess the cadmium transference and storage in the tissues using a solid phase extraction procedure with Saccharomycescerevisae. Fractionation of free (or labile) cadmium and cadmium protein (possibly metallothionein) (Cd-P) in animals exposed to 200 µg L-1 for 21 days in gills and hepatopancreas were carried to assess the cadmium transference and storage in the tissues using a solid phase extraction procedure with Saccharomycescerevisae. In gills, cadmium was found mainly in the free form, while in hepatopancreas the metal was found mainly bound to the protein (Cd-P). It may be inferred that, absorbed through gills, cadmium was transferred and stored in the hepatopancreas.

A diluição isotópica do B enriquecido em 94,14 átomos % em 10B fornecido durante o cultivo de mudas de cafeeiro foi avaliada na parede celular, núcleo e cloroplastos de células foliares. Para isto foi necessária a determinação de 11B/10B em pequenos volumes de amostras conseguidas pelo processo de fracionamento por centrifugação diferenciada. As determinações isotópicas foram efetuadas por espectrometria de massas com fonte de plasma acoplado indutivamente (ICP-MS) utilizando-se nebulizador de injeção direta (DIN). Razões isotópicas de B entre 1,002 e 1,326 foram determinadas em 50 mL das amostras enriquecidas com precisão caracterizada por RSD<1,5%. As concentrações de B encontradas nas frações celulares variaram entre 3,3 e 10,8 mg g-1, e em média os átomos % de 10B foram 46,7; 44,5 e 48,8 na parede celular, núcleo e cloroplasto, respectivamente. O limite de detecção foi estimado em 0,5 ng B mL-1.

Enriched 10B (94.14 atom %) was supplied to coffee plantlets for three months. Then boron isotope ratios were determined in the leaf cell compartments, cell wall, nuclei and chloroplast, after a sub-cellular fractionation procedure. The isotopic measurements were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) provided with a direct injection nebulizer (DIN), introducing a sample volume of 50 mL. Isotopic ratios from 1.002 to 1.326 were determined with precision characterized by RSD lower than 1.5% for the enriched cell fractions with B concentrations ranging from 3.3 to 10.8 mg g-1. The detection limit (3s) was 0.5 ng B mL-1. The average enrichments in 10B atom % found in the cell walls, nuclei and chloroplasts were 46.7, 44.5 and 48.8, respectively.