The elemental composition of pine trees as a function of age was achieved by the tree-ring method. By using instrumental neutron activation analysis, trace elements were determined in individual rings ofPinus elliottii var.elliottii of 32, 14 and 9 years, from an implanted forest ofPinus sp., Buri, São Paulo, far away from industrial pollution. Different components of the system such as needles, pith, bark, soil and litter were also analyzed for 18 elements (As, Br, Ce, Co, Cs, Eu, Fe, Hf, K, La, Mn, Na, Rb, Sc, Sm, Yb, Zn, and Zr). Al, B, Ba, Ca, Fe, K, Mg, and P concentrations were determined by atomic absorption and/or emission spectrometry (AAS; ICP-AES). Some elements have showed similar radial distribution of the concentration for the three ages. Abrupt concentration changes in the pith and ring-bark boundary corresponding to the first and last growth rings were observed.
Authors:M. Bacchi, E. Fernandes, and H. de Oliveira
After more than ten years working with multicomparator instrumental neutron activation analysis, mainly applied to the characterization of environmental samples, the Radioisotopes Laboratory (CENA/USP) started changing gradually to the k0-method in 1997. The main activities developed, as well as some of the results obtained, are presented here. Even though there is much more work to be done, the good quality of the results and the possibility of elemental determinations without the co-irradiation of standards may lead to the definitive adoption of the k0-method in a near future.
Neutron activation analysis was performed on aluvial soil samples from several sites on the floodplains of the Amazon River and its major tributaries for trace elements determination. The spatial and temporal variations of chemical composition of floodland sediments in the Amazon basin are discussed. No significant difference was found in trace elemental distribution in the floodland soils along the Amazon main channel, even after the source material has been progressively diluted with that from lowland draining tributaires. It was also seen that the average chemical composition of floodplain soils compares well with that of the suspended sediments.
A procedure for the simultaneous determination of241Am and239Pu or238Pu was carried out in samples such as air filters, sweep-tests, aqueous solutions and urine. The method described here includes a previous treatment of the samples in accordance with the type of matrix in which the actinides are included and a liquid scintillation counting using a two-phase cocktail. The upper detection limit was estimated to be 50 mBq for a 50-minute counting time.
Authors:H. Oliveira, E. Fernandes, M. Bacchi, G. Sarriés, and F. Tagliaferro
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.
Authors:L. Lara, E. Fernandes, H. Oliveira, M. Bacchi, and E. Ferraz
The interactive processes operating on the continental shelf adjacent to the river mouth control the amount and the characteristics of the Amazon discharge reaching the Atlantic Ocean. In this study, the distribution of trace elemental concentrations, with emphasis to the rare-earth elements, in sediment cores collected at several stations from the Amazon continental shelf during the falling water period was investigated by instrumental neutron activation analysis. Cores from the terrigenous and blue water zones have relatively uniform REE concentrations throughout the profile. Cerium anomalies for samples of the upper section of the eight stations are consistently positive and of high values (normally >2). Similar variation in the elemental concentration ratios between the seabed sediments and Amazon River suspended sediments was seen for stations located in the biogenic and blue water zones, with an enrichment for Ce, Sm, Fe, Th, and Sc and a depletion for the La, Eu, Tb, Yb, Co, Cr, Cs, Hf, Ta, and Zn. The shale-normalized REE patterns from shelf sediments are enriched in LREE relative to HREE, with enrichment factors varying from 1.5 for stations near the river mouth (terrigenous zone) to 1.9 for stations located far in the blue water zone. Published data for the Amazon River suspended sediment agree remarkably well with this observation of LREE-enrichment.
Authors:K. C. S. Almeida, H. Oikawa, J. Oliveira, and C. L. Duarte
A major concern with leaking petroleum is the environmental contamination by the toxic and water-soluble components such as
benzene, toluene and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant
toxicity. All BTX compounds are depressants to the central nervous system. Consequently, BTX are priority pollutants and their
occurrence has led to the development of several physical, chemical and biological methods for their removal. The use of nuclear
technology for protection and conservation of the environment, by the destruction of toxic organic compounds present in the
environmental, drinking water, soils and industrial sewage has been the object of study of several authors in Brazil and in
the world. The objective of this paper is to present the preliminary results of the study of contamination of the seawater
by the main pollutants of the output and transport of petroleum, such as benzene, toluene and xylene, and their removal by
the exposure to the ionizing radiation.
Authors:H. P. de Oliveira, J. Rieumont, C. Nogueiras, D. Souza, and R. Sánchez
The thermal degradation of an amphiphilic block copolymer poly(ethylene)-b-poly(ethylene oxide)-carboxylic acid terminated (PE-b-80%PEO–CH2COOH) and its salt obtained as intermediary product from chemical oxidation of the end group of poly(ethylene)-b-poly(ethylene oxide) (PE-b-80%PEO) has been studied using a thermogravimetric mass spectrometry (TG/MS) coupled system. The isothermal fragmentation of PE-b-80%PEO–CH2COOH showed a more complex fragmentation pattern than PE-b-80%PEO owing to the simultaneous occurrence of the polyether block and the carboxylic end group fragmentations. This led to the appearance of four overlapping ion current peaks of fragments with m/z 44 and two peaks relative to m/z 18 at different times by acid-terminated copolymer. For the PE-b-80%PEO copolymer, two ion current peaks associated to m/z 44 and one large peak relative to m/z 18 fragments were detected. The intermediary product (PE-b-80%PEO–CH2COO− K+) showed differences related to the fragmentation behavior. It has more defined ion current signals and presented characteristic peaks attributed to m/z 43 fragment at the very beginning of the thermal degradation process, which it not detected in the acid copolymer.
Authors:P. Oliveira, H. Stulzer, L. Bernardi, S. Borgmann, S. Cardoso, and M. Silva
In the present work, the thermal decomposition of sibutramine hydrochloride monohydrate (SBT) (an appetite suppressant agent)
was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Solid-state
characterization was carried out by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), scanning electron
microscopy (SEM) and X-ray powder diffraction (XRPD). Isothermal and non-isothermal methods were employed to determine the
kinetic data of decomposition process. From isothermal experiments, activation energy (Ea) can be obtained from slope of ln t versus 1/T, and the value obtained was 96.06 and 101.43 kJ mol−1 in N2 and air atmospheres, respectively. For non-isothermal method Ea can be obtained from plot of logarithms of heating rates, as a function of inverse of temperature, resulting in a value
of 96.56 and 98.22 kJ mol−1 in N2 and air atmospheres, respectively. The compatibilities of several commonly used pharmaceutical excipients (microcrystalline
cellulose, magnesium stearate, colloidal silicon dioxide, lactose monohydrate) and empty hard-gelatin capsules with SBT were
evaluated using DSC. The 1:1 physical mixtures of these excipients with SBT showed physical interaction of the drug with magnesium
stearate. On the other hand, DRIFT results did not evidence any chemical modifications.