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- Author or Editor: F. Tagliaferro x
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Abstract
Inorganic components were surveyed of some Brazilian cigarette tobacco by INAA. Sixteen different brands were taken from the consumer market and analyzed for As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, K, La, Na, Rb, Sc, Sm, Sr and Zn elements. Comparisons between the results from this work and those originated from several cigarette tobacco producing countries, indicate significant variation in the levels of some elements.
Summary
A random sampling was carried out in the coffee beans collected for the preparation of the organic green coffee reference material in view of assessing the homogeneity and the presence of soil as impurity. Fifteen samples were taken for the between-sample homogeneity evaluation. One of the samples was selected and 10 test portions withdrawn for the within-sample homogeneity evaluation. Br, Ca, Co, Cs, Fe, K, Na, Rb, Sc and Zn were determined by instrumental neutron activation analysis (INAA). The F-test demonstrated that the material is homogeneous for Ca, Co, Cs, K and Sc, but not homogeneous for Br, Fe, Na, Rb and Zn. Results of terrigenous elements suggested negligible soil contamination in the raw material.
Abstract
Aiming at the determination of toxic and essential elements in Brazilian commercial bovine milk, 25 ultra high temperature (UHT) milk samples were acquired in the local market of Piracicaba, SP. The samples were freeze-dried and analyzed by instrumental neutron activation analysis (INAA) allowing the determination of Br, Ca, Co, Cs, Fe, K, Na, Rb and Zn. When the results were expressed as concentration (mg·l−1) no significant differences were found. However, considering the dry matter, results showed a clear difference between the mass fractions (mg·kg−1 d.w.) of skim milk and whole milk for the elements Br, Ca, K, Na, Rb and Zn, indicating that the removal of fat caused a concentration effect in the dry matter of skim milks. Discrepancies were found between the concentrations of Ca and Na measured by INAA and the values informed in the labels. Ca showed variations within 30% for most samples, while concentrations of Na were up to 190% higher than informed values. The sample preparation and the INAA procedure were appropriate for the determination of Br, Ca, Co, Cs, Fe, K, Na, Rb and Zn in milk samples.
Abstract
This study investigated the representativeness of samples for assessing chemical elements in milk bulk tanks. Milk samples were collected from a closed tank in a dairy plant and from an open top tank in a dairy farm. Samples were analyzed for chemical elements by instrumental neutron activation analysis (INAA). For both experiments, Br, Ca, Cs, K, Na, Rb and Zn did not present significant differences between samples thereby indicating the appropriateness of the sampling procedure adopted to evaluate the analytes of interest.
Abstract
The degree of homogeneity is normally assessed by the variability of the results of independent analyses of several (e.g., 15) normal-scale replicates. Large sample instrumental neutron activation analysis (LS-INAA) with a collimated Ge detector allows inspecting the degree of homogeneity of the initial batch material, using a kilogram-size sample. The test is based on the spatial distributions of induced radioactivity. Such test was applied to samples of Brazilian whole (green) coffee beans (Coffea arabica and Coffea canephora) of approximately 1 kg in the frame of development of a coffee reference material. Results indicated that the material do not contain significant element composition inhomogeneities between batches of approximately 30–50 g, masses typically forming the starting base of a reference material.
Abstract
Epiphytic bromeliads have been used as biomonitors of air pollution since they have specialized structures in leaves for absorbing humidity and nutrients available in the atmosphere. Leaves of five bromeliad species were collected in the conservation unit Parque Estadual Ilha do Cardoso, São Paulo State, Brazil, and analyzed by INAA. Vriesea carinata was the species showing most accumulation, with the highest mass fractions of K, Na, Rb and Zn. Similar results were previously found for the same species collected in the dense ombrophilous forest. Chemical composition of bromeliads provided an indication of the atmosphere status in the conservation unit.
Abstract
Resuspended soil and other airborne particles adhered to the leaf surface affect the chemical composition of the plant. A well-defined cleaning procedure is necessary to avoid this problem, providing a correct assessment of the inherent chemical composition of bromeliads. To evaluate the influence of a washing procedure, INAA was applied for determining chemical elements in the leaves of bromeliads from Vriesea carinata species, both non-washed and washed with Alconox, EDTA and bi-distilled water. Br, Ce, Hg, La, Sc, Se, Sm and Th showed higher mass fractions in non-washed leaves. The washing procedure removed the exogenous material without leaching chemical elements from inside the tissues.
Abstract
In a preliminary study performed with the waste rocks from the future uranium mine to be explored in Brazil, 106 samples were taken from the eight main lithologies found in the massif and analysed by instrumental neutron activation analysis (INAA) for 20 elements. For samples from the same lithology, a high variability in the concentration of most of the elements was found (coefficient of variation larger than 20%), which might be attributed to either insufficient homogenisation of minerals or to local variation within lithology. The hypothesis that the variability within the lithology does not have an influence to the total variability was tested by analysing 5 replicates of the 5 most contrasting samples from the predominant lithology (plagioclase-microcline-gneiss), chosen after applying statistical evaluation (principal components and cluster analyses). Results indicated that homogenisation of samples was adequate due to low variation among replicates. The hypothesis tested was rejected with a confidence level higher than 99% for all the elements, corroborating the large intra-lithology variability.
Abstract
Depending on the harvest conditions, coffee beans can be contaminated by soil when dropped to the ground. It is well known that agricultural soils act as sinks for agrochemicals applied to the crops. While coffee is brewed, substances present in the roasted and ground coffee beans are extracted by hot water, emphasizing the need to assess the possible transfer of impurities from the soil to the beverage. Soil-contaminated samples of roasted coffee beans were split into 2 groups according to the treatments: (a) washed and ground and (b) only ground. Brewing was performed in a household espresso machine for both coffees. The resulting beverage was freeze-dried and the elemental composition determined by instrumental neutron activation analysis (INAA). The mass fractions of the terrigenous elements Fe, La, Sc, Sm and Th in the freeze-dried non-washed coffee beverages were, at least, 2 times higher than in the washed samples. These elements are tracers of the soil, indicating that the impurities from the soil reached the beverage.
Abstract
Soil analysis could improve environmental studies since soil is the main source of chemical elements for plants. In this study, soil samples collected at 0–10 cm depth under tree crown projection were analyzed by INAA. Using the chemical composition of the leaf previously determined, the leaf-soil transfer factors of chemical elements could be estimated for the Atlantic Forest. Despite the variability of the intra-species, the transfer factors were specific for some plant species due to their element accumulation in the leaves. Similar Br-Zn combined transfer factors were obtained for the species grouped according to habitats in relation to their position (understory or dominant species) in the forest canopy.
