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  • Author or Editor: M. Armelin x
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Abstract  

Brazilian fertilizer legislation considers the total concentration of micronutrients as being the guarantee of their presence in fertilizers. This fact allows the use industrial by-products as micronutrient source for fertilizers, which brings the risk of the presence of high amounts of toxic elements that may lead to soil contamination. The purpose of this study was to determine the micronutrient and contaminant contents in six Brazilian commercial phosphate fertilizers and to evaluate the phytoavailability of elements from soils treated with these fertilizers. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine the contents of the elements. As, Cd, Co, Cr, Fe, Mo, Na, Sb and Zn were detected in fertlizers. Concentrations in vegetal tissue were not modified by the treatments, except for Cd, which was increased due to fertilizers application.

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Abstract  

Instrumental neutron activation analysis (INAA) was applied to determine the elements Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn, Na, Rb, S, V, Zn in five varieties of Brazilian corn, resulting from the studies carried out in order to increase their protein contents. The accuracy of the method was evaluated by means of reference material analysis. In general, the precision of the method was lower than 15%, except for Cu, I and S. Sensitivity and detection limit were also determined. Besides, tryptophan contents were determined. It was observed that the tryptophan content in improved corn samples was twice as large as in the normal samples. However, the same ratio was not observed in the inorganic element contents.

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Abstract  

The present paper describes radiochemical separation procedures developed for the determination of seven elements: As, Cd, Cr, Cu, Hg, Sb and Se in different Brazilian regional diets. In the case of the elements As, Hg, Sb and Se, the procedure was based on retention in inorganic exchanger TDO (tin dioxide) and determination of Hg by extraction with Ni(DDC)2. For determination of Cd, Cr, Cu and Se the procedure chosen was based on retention in inorganic exchanger HMD (hydrated managese dioxide) and extraction of Cu and Cd as diethyldithiocarbamate compounds. The accuracy and precision of the methods studied were tested by means of analyses of different reference materials. Due to the lack of data on trace element levels in Brazilian foodstuffs and diets, these methods were applied to determination of these elements in different Brazilian regional diets. These diets were supplied by the Food and Experimental Nutrition Department of the Faculty of Pharmaceutical Science, University of São Paulo. The daily dietary intake values for these diets are presented for As, Cd, Cr, Cu, Hg, Sb and Se.

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Abstract  

Instrumental neutron activation analysis (INAA), followed by gamma-ray spectrometry, was used to determine the concentration of K, Ca, Mg, Na, Zn, Fe, Mn, Mo, Co, Cr, La, Eu and Th in six species of legumes and three species of grasses. Each species of forage was cultivated on two differet oxisols, that is, a red yellow Latossol and a dark red Latossol, with the aim of comparing the influence of the soils in the mineral extraction. Besides, on each kind of soil, two different limestone concentrations were used in order to verify how the soil pH correction could influence the elemental absorption in each species, and at the same time; to search for an optimum value of limestone concentration for each soil.

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Abstract  

Instrumental neutron activation analysis (INAA) was applied to estimate the concentrations of Ca, Co, Cr, Cu, Fe, K, Mg, Mo, Mn, Na, Se and Zn in hair samples from Holstein-Friesan male calves, which were infested withBoophilus microplus larvae and, also from healthy animals. These results were obtained in order to evaluate if is there a significant difference between the trace element concentrations in hair samples from infested and healthy animals.

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Summary  

Field trial was performed at the experimental farm of Southeast Embrapa Cattle, São Carlos - SP, Brazil, on a 16 year old Brachiaria decumbens pasture, grown on a distrophic Hapludox (Oxisol), recovered by the use of limestone and fertilizer. The experiments were carried out in random blocks, with 6 replications and 5 treatments. The 100 m2 blocks were established in the pasture. Each block received a sequence of limestone doses of 0, 1, 2, 4 and 8 t/ha. The forage samples were taken one year after limestone application on soil surface. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine mineral contents. The statistical analysis showed a negative linear correlation of Br, Co, Cr, Mn and Zn contents in forage with the limestone doses, while the uptake of Mg was affected in a positive way.

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Abstract  

The present paper describes radiochemical separation procedures developed for the determination of the elements As, Cr, Hg, Sb and Se in biological reference materials. The methods chosen utilize ion exchange, retention on inorganic exchangers and solvent extraction techniques for the isolation of the elements of interest. These procedures are more rapid than previously used methods, such as distillation and precipitation. As to the sample dissolution, the following procedures were tested using radioactive tracers and reference materials: treatment of the materials in teflon bombs with a mixture of HNO3+H2SO4 or HNO3 only in a normal oven, and with HNO3 in a microwave oven using specially designed digestion bombs.

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