共查询到20条相似文献,搜索用时 15 毫秒
1.
Determination of boron in water samples by chemical prompt gamma neutron activation analysis 总被引:1,自引:0,他引:1
P. S. Ramanjaneyulu Y. S. Sayi T. Newton Nathaniel A. V. R. Reddy K. L. Ramakumar 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):411-414
Boron concentration has been determined in groundwater samples, collected from Khuchch, Gujarat, India, by prompt gamma neutron
activation analysis (PGNAA) after selective separation and pre-concentration by solvent extraction with 10% 2-ethyl hexane
1,3-diol in CHCl3. Solvent extraction separation helped to eliminate the interfering elements in PGNAA determination of boron. The sensitivity
of PGNAA is found to be 18.83 cps/mg B based on the slope of a calibration plot obtained by carrying out measurements on synthetic
boric acid samples containing boron in the range of 30–150 μg. Detection limit of the method is 0.2 μg/g counted for 35,000
seconds at a sample size of 15 gram. The precision (relative standard deviation at 1σ level) and accuracy of the method is
5%. The analytical results of the present method agreed well with well-established spectrophotometric determination of boron
as boron-curcumin complex and inductively coupled plasma atomic emission spectroscopy (ICP-AES). 相似文献
2.
It was found that Cu and Se can be relatively easily and accurately determined by preconcentration of Cu and Se prior to the determination by neutron activation analysis with the short-lived IRN's (Indicator Radionuclides)66Cu and77mSe. The method consists of wet acid digestion followed by coprecipitation with lead tetramethylenedithiocarbamate. The precipitate was collected, irradiated and counted. The validity of the method was confirmed both by internal checks, as the measurement also by75Se and by the use of two reference material of biological origin. The limit of detection was found to be 20 ng Se and 50 ng Cu for a 0.1 g sample. 相似文献
3.
A. I. Saleh J. R. W. Woittiez G. D. Wals H. A. Das 《Journal of Radioanalytical and Nuclear Chemistry》1990,140(2):357-363
A neutron activation analysis method for the determination of Se(IV) in natural waters is described. It is based on the coprecipitation of the metal dibenzyldithiocarbamate with phenolphthalein. The precipitate is collected on 0.45 m membrane filters and selenium is determined by instrumental neutron activation. A Se(IV) radiotracer (75Se, T=120 d) was used to establish optimum conditions and to evaluate the chemical yield. Samples of sea and canal water were analyzed. 相似文献
4.
A. I. Saleh S. W. Al Rmalli F. M. Milad 《Journal of Radioanalytical and Nuclear Chemistry》1993,168(1):23-27
Lanthanide (Ln) levels in plasma and tissues from colorectal patients and healthy subjects were determined by radiochemical neutron activation analysis. Results, precision, accuracy and sensitivity are presented and discussed. Mean plasma levels of La, Ce, Nd, Eu and Yb were significantly higher (p<0.01) in adenoma and adenocarcinoma patients compared to control subjects. Increasing concentrations of plasmatic La, Eu and Yb as well as Ln levels in tissue from healthy subjects, adenomatous polyps, and adenocarcinoma (ADK) patients were observed. Measured tissue levels of Ln were constantly higher in ADK and adenomatous polyps than in the adjacent normal tissues. These findings may reflect impaired calcium metabolism possibly involved in the early process of carcinogenesis leading to the development of ADK.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria. 相似文献
5.
6.
Selenium (0.2–5 ppb) is coprecipitated with hydrated iron(III) oxide, dissolved in acid, reprecipitated as the element and determined by molecular emission cavity analysis. For a 250-ml water sample, the detection limit is 0.2 ppb. For <5 ppb selenium there is no need for coprecipitation. 相似文献
7.
K. H. Lieser M. Flakowski P. Hoffmann 《Fresenius' Journal of Analytical Chemistry》1994,350(3):135-138
The problems encountered in the determination of trace elements in small sample volumes of the order of 1 to 10 l (e.g. in droplets of water) are discussed. Total reflexion X-ray fluorescence (TXRF) and neutron activation analysis (NAA) are applied for the determination of Na, Mg, K, Ca, Mn, Fe, Co, and Cu in concentrations of 0.01 to 10 mg/L in 1 to 10 L of water. The applied methods are described, the results are discussed and the advantages of TXRF are brought forward. 相似文献
8.
Kenji Tomura Hideo Higuchi Nobuyoshi Miyaji Naoki Onuma Hiroshi Hamaguchi 《Analytica chimica acta》1968
A lithium-drifted germanium detector combined with chemical group-separation has been utilized for the determination of rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb and Lu) in rock samples by neutron activation. This procedure has the advantage of a low background level which cannot be attained in the non-destructive method. The combination of the Ge(Li) detector and chemical group-separation also offers a distinct simplification in the correction of contributions from other nuclides. For optimum utility of a Ge(Li) detector in neutron activation analysis, chemical group-separations are recommended. 相似文献
9.
M. Dermelj V. Stibilj J. Stekar A. R. Byrne 《Fresenius' Journal of Analytical Chemistry》1991,340(4):258-261
Summary Regarding the favourably sensitive nuclear characteristics of iodine and of selenium but the very different half lives of their induced nuclides 128I and 75Se, a radiochemical neutron activation analysis method for simultaneous determination of these elements in a single sample was developed. It is based on the double irradiation LICSIR technique — Long Irradiation for Se (40h), Cooling (a week or more), Short Irradiation for iodine (1–15 min) with following Radiochemistry. After the second short irradiation, the sample is ignited in an oxygen flask and iodine and selenium are sequentially and selectively extracted as elemental iodine and 5-nitro-2,1,3 benzoselena diazole chelate. With the described method biological samples were analysed and the reliability of the results was checked by the analyses of different standard reference materials. Good agreement with certified values and high radiochemical purity of the spectra show the applicability of the radiochemical separation developed. 相似文献
10.
J. R. W. Woittiez B. J. T. Nieuwendijk 《Journal of Radioanalytical and Nuclear Chemistry》1987,110(2):603-611
This paper presents the results of the application of a fast rabbit system and a high thermal neutron flux to neutron activation analysis of selenium in environmental samples. The short-lived radionuclide77mSe, (17.5s) is used for analysis. Results are presented for selenium in sea-water and rain-water, in biological reference materials, in food-stuffs and milk powder, in human hair and human blood-serum. 相似文献
11.
M. G. Ventura M. C. Freitas A. M. G. Pacheco 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(2):197-200
The replicate sample instrumental neutron activation method was optimized and used for the determination of selenium in foodstuffs.
The method was reliable, yielding accurate results. Lower detections limits were obtained after each successive irradiation.
Different irradiation conditions were used depending on the type of sample. For samples with higher selenium contents (meat,
fish, eggs), the measured selenium in the first replicate is in all cases larger than the detection limit, but a better accuracy
was obtained with a larger number of replicates (2–3 replicates). For samples with extremely low selenium contents (vegetable
samples), at least seven replicates were necessary to obtain a concentration value two times larger than the detection limit. 相似文献
12.
Determination of selenium in human diets by radiochemical neutron activation analysis. 总被引:1,自引:0,他引:1
A post-irradiation radiochemical separation technique was tested for the determination of selenium levels in diet samples, collected by using a duplicate portion technique, from both rural and urban population groups in Turkey. The technique involved sample irradiation, acid digestion, selective distillation, precipitation and filtration steps. During the separations it was possible to determine the yield of each sample using a stable selenium carrier. An average chemical yield of 71 +/- 3% was obtained for the radiochemical neutron activation analysis. For samples from urban and rural regions, the average selenium concentrations obtained were 0.14 +/- 0.04 and 0.07 +/- 0.02 mg kg-1, respectively. It was also possible to determine daily dietary selenium intakes, which were found to be 81 +/- 41 micrograms and 23 +/- 11 micrograms for the urban and rural groups, respectively. Although daily selenium intakes were found for a small number of subjects in this study, the separation technique developed can be used for determination of the selenium status in larger population groups. 相似文献
13.
The method described here involves the irradiation of biological samples and a g quantity of standard with thermal neutrons at the self-serve position in the CIRUS reactor, followed by dissolution of the sample and standard in the presence of milligram amounts of carrier. Both the sample and the standard are subjected to substoichiometric extraction under controlled experimental conditions with ethyl thioacetoacetate into chloroform. An aliquot of the organic phase is counted on a -spectrometer. The concentration of Hg in various biological samples and the accuracy, precision, and sensitivity of the method are discussed. 相似文献
14.
Manasi Rajadhyaksha Z. R. Turel 《Journal of Radioanalytical and Nuclear Chemistry》1986,106(2):99-105
A method has been described for the determination of trace amounts of copper in biological samples by thermal neutron activation analysis, involving radiochemical separation of copper from irradiated matrix employing substoichiometric extraction of Cu/II/ with 2-mercaptobenzothiazole /2-HMBT/ into chloroform. 4.01 g of Cu/II/ can be determined with an accuracy of 3.13% and precision of 1.08%. 相似文献
15.
J. E. Whitley A. B. Moyes P. Bowden 《Journal of Radioanalytical and Nuclear Chemistry》1979,48(1-2):147-158
The significance of rare earth distribution patterns in trace element geochemistry is briefly reviewed. Established methods
for their determination at the Reactor Centre by instrumental and radiochemical techniques are described, and examples of
recent applications discussed. 相似文献
16.
H. Higuchi K. Tomura H. Hamaguchi 《Journal of Radioanalytical and Nuclear Chemistry》1970,5(2):207-222
A Ge(Li) detector combined with cation exchange separation has been used for the determination of 12 rare-earth elements (La,
Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) in rock samples by neutron activation analysis. After purification by the
conventional hydroxide-fluoride precipitation, the rare-earth elements are separated into two fractions, light (La-Tb) and
heavy (Ho-Lu), by EDTA cation exchange, and the γ-activities of the two fractions are measured by a Ge(Li) detector. The heavy
rare-earths, such as Ho, Er, and Tm, can be easily γ-counted without serious interference from the intense Compton background
and photopeaks due to the light rare-earths such as140La,153Sm,152Eu, and160Tb. The chemical yields (60%) for the individual rare-earths are determined by a reactivation technique. The results obtained
for the U.S. Geological Survey standard rocks G-1 and W-1 are compared with the previously reported data. 相似文献
17.
The determination of Al2O3, in bulk coal samples to an accuracy of about 0.2% Al2O3 has been achieved by means of a thermal-neutron activation technique based on the reaction 27Al(n,γ)28Al. In the analysed samples, which had widely different compositions, the Al2O3 concentrations ranged from 1 to 11% and the ash contents from 7 to 40%. Al2O3 concentrations measured by x-ray fluorescence showed a linear relationship with both the 1.78-MeV γ-ray count following the decay of 28Al and the thermal-neutron count near the samples during irradiation. The linear relationship, which was obtained by regression analysis of the experimental data, determined the Al2O3concentrations with a standard deviation of 0.24% Al2O3. The particle sizes in the samples ranged from —0.5 to —40 mm, the moisture contents ranged from 1 to 6%, and the sample weights ranged from 8 to 11 kg. However, inclusion of these parameters in the regression analysis did not significantly improve the results for Al2O3. 相似文献
18.
A neutron activation method for the rapid determination of dysprosium in rocks, based on simple chemical separation and γ-spectrometry with a lithiumdrifted germanium detector, is described. The 94.7-keV photopeak of dysprosium-165 (2.3 h half-life) was measured. Several geochemical standard rocks covering a variety of rock types were analyzed. The detection limit was 0.005 μg of dysprosium. A precision of ±4.7% was obtained on 7 separate analyses of a basalt standard rock. The accuracy of the method is discussed. 相似文献
19.
A rapid instrumental system for measuring selenium via 17 second77mSe has been applied to the analysis of a wide variety of biological specimens encountered in biomedical research. The reliability
and versatility of the method is documented for serum and animal tissue specimens. Analysis results for SRM 1577 bovine liver
show excellent accuracy and precision. 相似文献
20.
The determination of As, Cd, Cr, Hg, Mn, Mo, Ni, Sb, and Se in two Nigerian rivers and two Nigerian harbor waters is described.
The water samples were preconcentrated by both evaporation at room temperature and freeze evaporation under reduced pressure.
Postirradiation chemical separation of sodium, using hydrated antimony pentoxide (HAP) in 6M HCl, and of bromine, by oxidation
with KMnO4 and subsequent removal by extraction with CHCl3, was employed. The measured concentrations of these elements in some water samples, which are relatively high, can be attributed
to local pollution. 相似文献