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1.
A technique is described for the determination by instrumental neutron activation analysis of the zonal distribution of trace elements in diamond. Individual diamonds were irradiated and then dissolved in stages into 10 to 20 fractions in molten sodium nitrate. The activity of the material dissolved in each fraction was measured using a well-shielded Ge(Li) detector. Because of the small sample sizes involved, many elements typically found in diamond were below the limits of detection even though the experimental conditions were optimised for high sensitivity. The data obtained for a clear, a green and a coated diamond are given here to show the scope of the method. High levels of some elements in the outermost layers of all the diamonds are thought to have been due the implantation of surface contaminants during neutron irradiation. Removal of the outer few microns of irradiated diamonds before counting will avoid this source of error.  相似文献   

2.
Thirty four elements were determined by instrumental neutron activation analysis in colourless, brown, and pink diamonds, with and without inclusions. These were compared with data obtained for similar elements in the host lamproite rock. The natural radioactivity of these samples was measured by instrumental techniques, and found to be negligible.  相似文献   

3.
The impact of tanning and electroplating industry on the eastern part of Barada River environment has been evaluated. Sediment, soil and plant samples were collected from nine sites at the river near the eastern industrial complex during 1999. Results of instrumental neutron activation analysis have shown high levels of Cr in sediment collected near the tanning factories; the highest value obtained being 2692 ppm. In addition, relatively high levels of Cr were also found in the agriculture soil collected near the riverbank in the industrial complex; Cr concentrations varied between 77 ppm and 327 ppm. However, Cr concentrations in plant leaves grown at riverbank were found low and this due to strong bounding of Cr to soil. Other trace metals such as copper and nickel were also high in sediment samples. The highest concentration of copper was about 4000 ppm, which is much higher than the natural levels; electroplating shops are the main source of this element in the area. Furthermore, concentrations of the studied trace metals have decreased as the sampling site distance became far from the industrial complex. In general, other trace elements were found to be at low concentrations, but the obtained data can be used as a baseline for future monitoring.  相似文献   

4.
Thirty-five natural diamonds from six widely differing localities, weighing from 3.6 mg to 305.3 mg were subjected to instrumental neutron activation analysis using high-resolution semiconductor gamma-spectrometry. By means of short-term and long-term activation in a nuclear reactor, Na, Sc, Cr, Mn, Co, La, Ce, Sm, Eu, Hf, Au, Hg, and Th were determined in all the samples, K, Sr, Ag, Cs, Ba, Yb, Lu and W in some, and qualitative determination was carried out with Ca, Fe, Ni, Ga, As, Zr, Sb, Tb, Dy, Ta, It and U. The study serves as a basis for the study of the relationship between the colour, morphology and luminescence of diamonds and their impurity contents.  相似文献   

5.
Instrumental neutron activation analysis /INAA/ technique has been applied to a water sample to determine the elemental concentrations. The sample was irradiated with a neutron flux of 1.2×1012 n cm–2 s–1 for two different periods followed by counting at three different decay times, using two coaxial type high-resolution Ge/Li/ detectors. The dominant elements determined in the water sample are Ca, Cl, Na, Mg, and K present in ppm-level while Co, I, Mn, Sm, and Sb are present in smaller amounts, approximately on the average 0.01 ppm. Only traces of other elements such as the rare-earth elements, Ag, As, Ba, Cu, Cd, Fe, Sr, W, Zn, seem to be present in the water sample.  相似文献   

6.
Instrumental neutron activation analysis has been applied to semiconductor grade silicon to study the concentration levels of impurity elements, the contamination during the single crystal growing process, and the vertical and radial distributions of impurities, along with the decontamination effect in the analysis. Twenty elements of Au, Br, As, W, Cr, Co, Na, Eu, La, Se, Zn, U, Th, Hf, Fe, Sb, Ag, Ce, Tb and Ta have been analyzed in p- and n-type wafers, single crystals and a polycrystal by a single comparator method using two comparators of gold and cobalt. Considerable surface contamination has been found and could be removed by etching the surface with nitric and hydrofluoric acid before and after irradiation. The impurity concentration has been found to be generally increased in the process of single crystal growth. The vertical and radial distributions of impurities have revealed that some impurity elements were more concentrated in the top region of a single crystal rod than in the middle region, and that Br, Cr, La, Eu and Sb were enriched in the central region and As, U and Fe in the outer region.  相似文献   

7.
Journal of Radioanalytical and Nuclear Chemistry - Neutron activation analysis (NAA) for Al determination in tree bark samples containing phosphorus and silicon was studied. The contributions of...  相似文献   

8.
Instrumental neutron activation analysis technique was applied for the determination of 20 elements in 54 silicate rock samples which belong to three sedimentary geological formations located in the western desert of Iraq. The samples along with USGS standards were irradiated in an IRT-5000 reactor at a neutron flux of 3.7·1013 n·cm–2·s–1 The following minor and trace element constituents have been determined: Na, K, Ca, Fe, Sc, Cr, Co, Zr, Ce, La, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Th and U.  相似文献   

9.
Forest Swiss soils from 39 locations sampled ad three depths each were extracted with a buffered solution of pH 4.65 containing EDTA. Nearly 30 elements were determined by instrumental neutron activation analysis in these extracts. The results obtained are discussed in terms of efficiency of the extractant, precision and accuracy. Summariszed results are presented for the quantities fractions of the elements extracted.  相似文献   

10.
Summary Instrumental neutron activation analysis (INAA) was used for the qualitative and quantitative analysis of sandstone samples of Aswan area, in South Egypt. The samples were properly prepared together with standards and simultaneously irradiated by a neutron flux of 7 . 1011 n . cm-2.s-1. in the TRIGA research reactor facilities in Mainz. The gamma-spectra from a hyperpure germanium HPGe detector were analyzed. The present study provides the basic data of elemental concentrations of a sandstone rock. The following elements have been determined: Na, K, Fe, Sc, Cr, Co, Zr, Ce, La, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. Energy dispersive X-ray fluorescence (EDXRF) was used for comparison and to detect elements which can be detected only by this method.  相似文献   

11.
The absolute concentrations of iodine, bromine and chlorine in milk, have been determined by epithermal neutron activation followed by high resolution gamma-ray spectrometry. Two kinds of milk commonly consumed in Israel have been investigated. The concentration of iodine, bromine and chlorine were found to be 0.18–0.30 g/ml, 2.02–2.85 g/ml and 0.65 mg/ml, respectively. The method is fast, selective, accurate and highly sensitive.  相似文献   

12.
Procedures for the determination of bromine by the reactions81Br(n, γ)82Br (T=35.4 h) and79Br(n, γ)80mBr (T=4.4 h). In the case of82Br a flat coaxial Ge(Li) crystal is used to measure the 619 keV photopeak. For80mBr a planar Ge(Li) detector is applied to measure the 39 keV γ-ray. The agreement between the data obtained with both techniques for some Standard Reference Materials is satisfactory.  相似文献   

13.
The Si determination with epithermal neutrons using the reaction28Si (n,p)28Al is described. Thermal neutrons are eliminated from the irradiation position with a BN-shield. Two first order interfering reactions with P and with Al necessitate appropriate corrections. The interfering reaction on Al is shown to depend heavily on the hydrogen (H) content of the sample, which therefore must be taken into account. The lower application range in plant samles is estimated to be 500 g g–1. Reproducibility is <5% in suitable cases, but not as good if the necessary corrections are large. The capacity is 25 samples per 8 h. The method is applied to 3 plant standards (rice, hay and pine needles) and to 47 samples of spruce needles. The applicability to different plant materials is mainly limited by their relative Al, P and Si concentrations. Literature values are use to find plant categories in which Si can be reasonably determined by instrumental epithermal neutron activation analysis (IENA).  相似文献   

14.
Because of the short half life of Al-28, the determination of aluminum by neutron activation is subject to many inaccuracies: variation of irradiation conditions between sample and standard, uncertainties in timing, and the effects of high and varying count rate, in addition to other sources of error that must be controlled even in work with long-lived nuclides. These errors can all be made smaller than the fundamental limit set by counting statistics, even when that limit is below 0.5 percent. The transfer function from the observed number of net counts to the counting rate at the end of irradiation is modeled as a product of three processes: radioactive decay and extending and nonextending dead time.The procedure has been applied to the analysis of NBS SRM 1633a Fly Ash. The mean concentration measured was 14.085% Al, with a standard deviation of the mean 0.023% Al for four determinations. The final results showed no significant imprecision beyond counting statistics. The accuracy of the method is shown by the analysis of high-purity single-crystal sapphire.  相似文献   

15.
Serum aluminum levels were determined by instrumental neutron activation analysis in 31 patients undergoing long-term haemodialysis. Aluminum-28 1.778 MeV (T 1/2=2.24 min) γ-rays produced by the thermal neutron reaction27Al(n,γ)28Al were detected. Successive irradiation of the samples at epithermal neutron fluence was performed to correct for the interference from the fast neutron reaction31P(n,α)28Al. Serum aluminum level in this group of subjects was adequately represented by a lognormal distribution with a mean and variance of 16.5 μg/l and 16.8 μg/l, respectively. The results obtained were found to be in agreement with serum aluminum determination performed by electrothermal atomic absorption spectrophotometry (r 2=0.97). Instrumental neutron activation can provide a rapid technique to routinely monitor long-term haemodialysis patients in order to identify individuals at greater risk to develop aluminum toxicity.  相似文献   

16.
To identify and improve the analytical technique for air pollution research, four kinds of environmental standard samples, i.e., airbome particulate matter, coal flyash, soil and pine needle supplied from the NIST and the IAEA were analyzed using thermal and epithermal neutron activation techniques. Sample irradiation was done at the irradiation facilities (neutron flux, 1 · 1013 n·cm–2·s–1) of the TRIGA MARK-III Research Reactor in the Korea Atomic Energy Research Institute. The accuracy and precision for the analysis of 40 trace and toxic elements in the samples were compared with the certified and reported values, respectively. In the analytical results of all standard reference materials, the relative standard deviation were within the 15% except for 11 elements and the relative error were agreed within the 10–20% except for 13 elements. The benefit of epithermal activation was investigated and the optimum analytical condition is reported.  相似文献   

17.
Indium (10–15,000 ppm) and tin (20–90%) are quantitatively determined in cassiterite samples by instrumental (thermal) neutron activation analysis, using semiconductor detectors and gamma spectroscopy. Precision is 7% or better for In and 5% or better for Sn. The detection limit is 2 ppm for In and 0.4% for Sn in Mexican cassiterites.  相似文献   

18.
19.
Instrumental neutron activation analysis was used to determine selenium concentrations in several marine organisms including two certified reference materials /NRCC lobster hepatopancreas, NBS oyster tissue/ and one uncertified material /IAEA fish homogenate/. The76Se/n, /77mSe/T=17.4 s/ reaction was successfully employed to achieve an overall precision between 3–10% and detection limits between 0.3–0.6 g/g. The accuracy of the results, as compared to the certified values, was in excellent agreement with the NBS material and only slightly lower /9%/ for the NRCC material.  相似文献   

20.
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.  相似文献   

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