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1.
Despite the role of iodine for proper development of the brain and the functions of the element, the accurate data on its concentration in brain tissue are largely lacking, the main reason being analytical difficulties associated with determination of the element especially at low levels. In this work, samples from human brain regions from Hungarian patients were analyzed using epithermal and radiochemical neutron activation analysis (ENAA and RNAA, respectively). The RNAA procedure is based on alkaline-oxidative fusion followed by extraction of elemental iodine in chloroform. The results were checked by the analysis of biological standard reference materials, namely bovine liver, bone meal and diet, and by comparison with previous results obtained by a different RNAA procedure. 相似文献
2.
V. L. Spate J. S. Morris C. K. Baskett M. M. Mason C. L. Reams D. Hunter W. C. Willett 《Journal of Radioanalytical and Nuclear Chemistry》1994,179(1):27-33
The role of fluorine in human health has become somewhat controversial. It is widely accepted as protective against dental caries, may be protective against osteoporosis, and has been very conservatively implicated with osteosarcoma in male rats. In this study, we repot on the development of a neutron activation analysis method and its application to the analysis of human nails. We have found that toenails collected in population-based epidemiology studies apparently reflect fluoride intake. 相似文献
3.
4.
J. Kučera G. V. Iyengar Z. Řanda R. M. Parr 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(3):505-509
Samples of diets from China, Japan, Korea, India, Pakistan and Philippines were analyzed using epithermal and radiochemical
neutron activation analysis (ENAA and RNAA, respectively) within the framework of the IAEA project “Reference Asian Man”.
The RNAA procedure was based on alkaline-oxidative fusion followed by extraction of elemental iodine in chloroform. The analytical
methods employed are discussed in terms of detection limits and uncertainties of the results obtained. For quality control
purposes a number of NIST biological reference materials, namely diets and foods were analyzed. Results for the diet samples
indicate that achieving the WHO recommended daily allowance for iodine may be a problem in most of the above given countries.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
W. B. Stroube Jr. W. C. Cunningham G. J. Lutz 《Journal of Radioanalytical and Nuclear Chemistry》1987,112(2):341-346
Epithermal-neutron activation analysis (ENAA) was applied to the analysis of foods for iodine. The procedure involves irradiation of wet foods in a boron nitride, vessel, followed by direct counting of the 442.9 keV gamma ray of128I without any processing of the sample. Three research reactors were evaluated for use in determining iodine by ENAA. The University of Virginia reactor at Charlottesville was chosen for this study because the reactor facilities minimized thermal heating of the boron nitride vessel, enabling irradiation of larger, more representative analytical portions. Iodine concentrations ranging from <0.003 to 0.74 g/g are reported for 17 different food matrices. 相似文献
6.
Iodine abundances in NBS biological SRMs and various organs of rats were evaluated by epithermal neutron activation analysis with a boron carbide filter. Detectability of iodine in different biological materials by this method is discussed.
相似文献7.
Determination of bromine and iodine in biological and environmental materials using epithermal neutron activation analysis 总被引:1,自引:0,他引:1
Xiaolin Hou Chifang Chai Qinfang Qian Chunsheng Li Ke Wang 《Analytical and bioanalytical chemistry》1997,357(8):1106-1110
Epithermal neutron activation analysis (ENAA) was applied to the determination of the contents of bromine and iodine in 40
biological and environmental standard reference materials and Chinese diets. Boron nitride (BN) for solid samples and BN+Cd
for liquid samples were adopted as shield material. Irradiation was carried out in inner and outer irradiation sites in a
Miniature Source Reactor (MNSR) for solid and liquid samples, respectively. The 443 keV photopeak of 128I and the 616 keV photopeak of 80Br were used. The precision of measurement (relative standard deviation) is 2∼6% for contents of iodine of more than 100 ng/g
and 8∼12% in the 20∼100 ng/g range in solid samples, and 12∼18% at less than 100 ng/ml in liquid samples. For bromine, the
precision of measurement is 2–8% for solid samples and lower than 13% for liquid samples. The detection limits under experimental
conditions varied between 10∼30 ng/g, 55∼95 ng/g and 25∼68 ng/g for iodine and 50∼150 ng/g, 200∼450 ng/g and 100∼300 ng/g
for bromine in ENAA with BN shield in inner irradiation sites, with Cd shield and BN+Cd shield in outer irradiation sites,
respectively.
Received: 13 June 1996 / Revised: 2 September 1996 / Accepted: 19 September 1996 相似文献
8.
Determination of iodine in milk products and biological standard reference materials by epithermal neutron activation analysis 总被引:1,自引:0,他引:1
The biologically essential trace element, iodine, has been determined in various milk products by epithermal neutron activation analysis /ENAA/ after sealing in quartz and irradiating under cadmium cover. The method was extended to several IAEA and NBS biological reference materials. 相似文献
9.
A fast pneumatic transfer facility was installed in Nuclear Engineering Teaching Laboratory (NETL) of the University of Texas
at Austin for the purpose of cyclic thermal and epithermal neutron activation analysis. In this study efforts were focused
on the evaluation of cyclic epithermal neutron activation analysis (CENAA). Various NIST and CANMET certified materials were
analyzed by the system. Experiment results showed 110Ag with its 25 s half-life as one of the isotopes favored by the system. Thus, the system was put into practical application
in identifying silver in metallic ores. Comparison of sliver concentrations as determined by CENAA in CANMET certified reference
materials gave very good results. 相似文献
10.
Classical activation analysis of fluorine by thermal neutrons has a limited application because of frequent interference from
chlorine, the short half life20F (11.4 s) and too high dead time of detectors. A procedure is described for fluorine determination using19F (n,p)19O reaction. Use of a boron carbide shield has no effect on the activity of19O (boron ratio −1) but considerably reduces background and interference due to18O (n, γ)19O reaction. The technique has been successfully applied to the determination of fluorine in organic compounds even in the
presence of large amounts of chlorine and oxygen. 相似文献
11.
Uranium in thorium matrixes or in minerals and ores containing thorium is determined by epithermal neutron activation analysis (ENAA). In some minerals and ores, such as monazite sands, the analysis can be carried out by purely instrumental means with no chemical separation of uranium or thorium from the irradiated matrix. For thorium compound matrixes with very low uranium contents, a rapid radiochemical separation method, based on the retention of uranyl ion on anion-exchange resins, is first carried out, before counting the gamma-ray peaks for239U in multichannel analysers coupled to NaI(Tl) scintillators or to Ge(Li) detectors. 相似文献
12.
J. S. Morris D. A. Sorrell C. L. Krueger 《Journal of Radioanalytical and Nuclear Chemistry》1995,194(1):61-69
Epithermal Instrumental Neutron Activation Analysis has been used to measure the concentration of uranium in eutectic salt solutions in support of a research program in which the actinide elements are separated from rare earths and other fission products using high-temperature electo-deposition. The uranium response over three decades in concentration follows a negative power function; and high concentrations of samarium interfere with the determination of uranium but can be accurately corrected. The EINAA method was successfully used to analyze NIST SRM 278 Obsidian and NIST SRM 1566a Fly Ash. 相似文献
13.
E. S. Gladney W. A. Sedlacek W. W. Berg 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(1):213-225
A comparative determination of bromine and iodine in three distinct air sampling media by instrumental thermal and epithermal neturon activation analysis is presented. Open ocean air samples from the mid-Atlantic region were collected on ultra-pure nylon, Nuclepore, and activated charcoal substrates. The bromine and iodine content of each substrate was determined by both epithermal and thermal activation techniques. Good agreement was found within most thermal-epithermal pairs. Relative to the thermal activation procedure, the epithermal technique yields peak/background ratio improvements ranging from a factor of 1.30 to 9.5. Nylon substrates showed the smallest improvement at 1.30 and both Nuclepore and activated charcoal substrates showed improvement factors of 6.7 and 9.5 for bromine and iodine respectively. 相似文献
14.
S. Landsberger D. J. O'Kelly J. Braisted S. Panno 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(3):697-702
Summary Halides, particularly Br- and Cl-, have been used as indicators of potential sources of Na+ and Cl- in surface water and groundwater with limited success. Contamination of groundwater and surface water by Na+ and Cl- is a common occurrence in growing urban areas and adversely affects municipal and private water supplies in Illinois and
other states, as well as vegetation in environmentally sensitive areas. Neutron activation analysis (NAA) can be effectively
used to determine these halogens, but often the elevated concentrations of sodium and chlorine in water samples can give rise
to very high detection limits for bromine and iodine due to elevated backgrounds from the activation process. We present a
detailed analytical scheme to determine Cl, Br and I in aqueous samples with widely varying Na and Cl concentrations using
epithermal NAA in conjunction with Compton suppression. 相似文献
15.
A method of determination of iodine (total and PBI) in serum, urine and other biological materials has been developed. The
method consists in a gamma-spectrometric measurement of128I activity after its radiochemical separation. The radiochemical separation procedure includes wet decomposition of the samples
in a nitric acid medium followed by a few separation steps, the essential step being the substoichiometric extraction of iodide
with a chloroform solution of tetraphenylarsonium chloride. Owing to the application of the substoichiometric separation,
a high radiochemical purity of the separated iodine is achieved and the determination of the yield of radiochemical separation
is not necessary. 相似文献
16.
G. Capote Rodríguez A. Hernández Rivero J. Moreno Bermúdez S. Ribeiro Guevara M. A. Arribére J. Molina Insfrán G. Pérez Zayas 《Journal of Radioanalytical and Nuclear Chemistry》1997,226(1-2):217-220
The physicochemical association of plutonium in soil near the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL) has been determined using selective sequential extraction techniques. Our results suggest that plutonium in surface soils is associated primarily with the hydrous oxide coatings of the soil (37±5.3%). Appreciable amounts of plutonium were also removed with the organic matter (22±2.8%) and carbonates (13±3.1%). On the other hand it appears that plutonium association with the soluble and exchangeable components of the soil is relatively small (>4.0%). The remainder of plutonium (21±4.7%) is tightly bound to the refractory silicate residue of the soil. Relatively little plutonium is available for physicochemical mobilization from the soil under the present prevailing conditions of the INEEL site. 相似文献
17.
The use of reactor epithermal neutrons in instrumental activation analysis is described for the determination of trace elements via long-lived isotopes. A boron carbide filter is used. Results of analyses of human erythrocytes, plasma, urine and some biological reference materials are given to demonstrate the applicability of the method to biological samples. Bromine, iron, cesium, rubidium, selenium and zinc and cobalt are determined. The method provides accuracy and reliability similar to conventional thermal neutron activation but is faster. Limits of detection attainable with the two techniques are compared. 相似文献
18.
A. U. Akamine M. A. Duchen Silva M. Saiki M. B. A. Vasconcellos S. L. de Andrade R. Fulfaro 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(3):607-609
Hair analysis is extensively used in forensic sciences, assessment of occupational or environmental exposure and in some cases
also for clinical and nutritional studies. Hair has a series of advantages in relation to other biomonitors, like blood and
urine, since it is very easy to collect, very stable at room temperature and it represents not only instantaneous concentrations,
but it can reveal the exposure along a given period of time. The assessment of environmental or occupational exposure to uranium
is generally done by means of urine analysis, although a few papers have described attempts to use hair as a biomonitor. In
the present work, epithermal neutron activation analysis has been used to establish base-line concentrations for a Brazilian
populational group, living in Sao Paulo and not exposed to uranium, either environmentally or occupationally. For quality
control, the reference materials Pine Needles NIST 1575 and Basalt USGS BCR-1 were used. The concentrations obtained for the
control population studied up to now varied from about 2 to 50 ng·g−1. 相似文献
19.
Determination of some elements by epithermal neutron activation analysis for the Arctic aerosol 总被引:1,自引:0,他引:1
S. Landsberger M. S. Basunia S. Schroit 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(3):823-828
Summary We have determined nineteen trace elements in 685 aerosol filter samples collected during 1964-1978 in northern Finland by the Finnish Meteorological Institute. In this paper we present some procedures and results for very short (~25 s), short (~3-54 min), and medium (12-35 h) lived isotopes as determined by epithermal NAA in conjunction with and without Compton suppression. Elements with a Iγ/σthratio are favorable to be determined by epithermal NAA. Silver was determined by a one minute epithermal irradiation because of a very short 110Ag half-life. Antimony, arsenic, cobalt, bromine, indium, iodine, potassium, silicon, tin, tungsten, and zinc were determined by a ten minute epithermal irradiation. For silver determination, samples were counted without transferring the filter from the irradiated vial, however, for ten minute irradiation all samples were transferred to a non-irradiated vial and counted both in the normal and Compton mode by the HPGe gamma-spectrometry system with a decay time of about 10 minutes and counting time of 15 minutes. Each day a maximum of 16 samples were irradiated and immediately following the short counting, these samples were loaded into an automatic sample changer in sequence of irradiation and counted for an hour in both normal and Compton modes. This has proven to be an extremely cost effective measure thus reducing the need to employ long-lived NAA to analyze other elements such as Ag, Co, Sn and Zn and Ag for air pollution source receptor modeling. 相似文献
20.
Epithermal neutron activation analysis (ENAA) was applied to measure quantitatively Cd and other elements in bone samples from control and Cd-fed rats. This method was found to be non-destructive to the bone samples, with no sign of radiolytic charring and was sensitive enough to detect and quantify Cd in bone samples at normal levels for mammals (viz. 0.5–1.0 g/g) and higher. Two different thermal neutron shield materials were utilized, namely cadmium and boron. The boron shield resulted in a 27% improvement in the detection limit of Cd in bone. The accuracy of ENAA for Cd was assessed by intercomparison with electrothermal atomic absorption spectrophotometry (ETAAS), and the results were in fair agreement (±23%) with those from ENAA. 相似文献