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Major and trace element contents in iron ore reference materials were investigated using k 0-instrumental neutron activation analysis ( k 0-INAA). To avoid iron interferences, radiochemical separation was developed ( k 0-RNAA). The determination of the investigated elements in the inorganic phase from hydrochloric acid solution was performed after radiochemical separation of iron by diisopropyl ether. It was found that after the Fe elimination, the limit of detection for some elements was much lower that enables their direct determination. The distribution of 39 elements (with intermediate/medium and long half-life radionuclides) after Fe removal was investigated. [ABSTRACT FROM AUTHOR]

In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For quality assurance purposes a procedure for determination of the overall chemical yield using spectrophotometry of the V-BPHA complex is described, and possible interferences are evaluated. The procedure was applied to the determination of vanadium in reference materials and selected food samples from Slovenia. [ABSTRACT FROM AUTHOR]

The aim of the work was to determine the short-term effect (19 days) of dietary As additions (30 µg As/g in the form As2O3) on the Se and I concentrations in eggs and tissues of 49-week-old Rhode Island Red laying hens. Se and I concentrations were determined in eggs collected from the 8th to the 10th and from the 17th to the 19th days of the experiment. After 19 days, blood was collected by anterior heart puncture, and after slaughter the liver, kidney, lung, muscle (musculus pectoralis superficialis) and feathers were collected. Se and I concentrations were determined by radiochemical neutron activation analysis and the results expressed on a dry matter basis. In the control and the exposed group, the highest Se concentrations were found in kidney, followed by liver, blood, lung, muscle, and feathers. In the control group the highest I concentration was found in feathers, followed by kidney, blood, lungs, liver, and muscle. In the trial group, the order was almost the same, except that blood concentration was lower than in liver. As2O3 added to the feed significantly increased the Se concentration in the lung (p = 0.0216), I concentration in muscle (p = 0.0112) and significantly decreased I concentration in blood (p = 0.0371). It had no effect on the concentrations of Se and I in egg yolk and white. [ABSTRACT FROM AUTHOR]

Iodine is one of the most important essential elements as demonstrated by the fact that its deficiency can cause goitre. Nevertheless, quantitative data on its concentration in biological materials, especially in the human brain, are scarce. There is therefore a demand for accurate and reliable information on iodine in these types of samples. The purpose of the present work was to determine the concentration of total iodine in some control human brain parts by rapid radiochemical neutron activation analysis. Our second goal was to determine I distribution between lipid fraction and in brain tissue without lipid by applying two types of solvent extraction methods. The results were checked by the analysis of biological standard reference materials with certified or literature values for iodine and good agreement was found. [ABSTRACT FROM AUTHOR]

Development of a method for very low level selenium determination in water soluble protein and peptide fractions, obtained after various separation procedures, is presented. A hydride generation atomic fluorescence spectrometry (HG-AFS) detection system was optimised and the influence of Cu(II), Sb(V), As(III) and HNO3 interferences in the measurement of Se by HG-AFS was investigated. A destruction procedure using HNO3 and H2O2 was also optimised and the average recovery of the digestion of a solution of selenomethioneine was 92 ± 4% (n=14). Combination of this digestion with the detection system gave reliable results. Accuracy was tested by comparison with two independent methods. A very low detection limit (DL) of 0.2 ng/g of measuring solution was achieved. The whole procedure from weighing to measuring was performed in the same Teflon tube. The addition of HNO3 to the fractions before long term storage at -20°C was necessary to prevent adsorption on the test tubes. Selenium was measured in water soluble protein and peptide fractions obtained after extraction, and Sephadex G-75 chromatography performed on liver samples from: i) hens exposed to As2O3, ii) hens fed with a high fat feed and iii) the certified reference material dogfish liver (CRM DOLT-2). Because of the very low DL we were able to observe the Se distribution in chromatographic fractions of samples of organisms which were not exposed to excess amounts of Se. The presence of selenium associated with metallothioneins was observed. [ABSTRACT FROM AUTHOR]

The neutron distribution in a defined volume (gradient) for different matrices (air, water, cellulose, biological material and silicon dioxide) in two typical irradiation channels (pneumatic tube (PT) and IC40-channel in the carousel facility) in the TRIGA Mark II reactor at the Jožef Stefan Institute (IJS) was studied. Our experiment was based on inserting Fe wires (flux monitors) into the chosen matrices. The wires were cut into small pieces after irradiation and the induced activities of 59Fe measured. The results showed that for the studied geometry the average spatial thermal neutron flux inhomogeneities (for five studied matrices) are about 2.3% in the PT-channel and about 2.9% in the IC40-channel. [ABSTRACT FROM AUTHOR]

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex ¶G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyrolysis and detection with cold vapour atomic fluorescence spectrometry (CVAFS). The sum of MeHg and Hg2+ was compared to total Hg results obtained by acid digestion and CVAAS detection. The accuracy of MeHg determination was checked by its determination using acid leaching at room temperature, solvent extraction, back extraction into Milli-Q water, ethylation, GC and CVAFS detection. For the insoluble phase it is recommended to use solvent extraction for MeHg and acid digestion CVAAS for total Hg. For determination of MeHg and Hg2+ in the lyophilised sample and water soluble fractions containing low concentrations of mercury species, the simultaneous measurement of MeHg and Hg2+ after alkaline dissolution is the most appropriate method. [ABSTRACT FROM AUTHOR]

Three groups of six hens each were fed for twelve days with diets containing 7.5, 15.0, and 30.0 mg arsenic per kg in the form of As2O3. A control group was included in the trial. The hens from each group were formed into three subgroups. The eggs of two hens, laid in three days, formed a composite sample. The As concentration in the egg whites and yolks was determined in duplicate by radiochemical neutron activation analysis. With increasing As concentration in the poultry feedstuff, its concentration in egg yolk and whitealso increased, but a plateau appears to be reached quite rapidly. The ratio between the As concentration in yolk and in white is nearly constant (1:3) for all three groups of hens, irrespective of the level of As in the feed. The concentration of arsenic in dry matter of whites was significantly higher than in the dry matter of yolks, while the concentrations of arsenic in fresh samples of yolks were higher in the comparison with fresh samples of whites, but the differences were not significant. [ABSTRACT FROM AUTHOR]