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1.
H. Münzel F. Michel P. P. Coetzee V. Krivan 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):267-273
The possible application of cyclotron-produced fast neutrons to activation analysis for oxygen based on the16O(n, p)16N reaction has been investigated. Neutrons were produced by bombarding a thick beryllium target with 22 to 45 MeV deuterons.
It was found that the sensitivity increases rapidly with the energy of the deuterons. Using 45 MeV deuterons and a 10 μA beam
current a sensitivity of about 20 counts per 1 μg oxigen could be achieved, enabling the determination of less than 1 μg oxigen.
In a direct comparison it was experimentally established that the sensitivity for cyclotron-produced neutrons assuming a deuteron
beam of about 10 μA, is up to two orders of magnitude higher than that achievable for 14 MeV neutrons with a flux of about
1010 n/s. The interference of fluorine is at about the same level for both the cyclotron-produced and 14 MeV neutrons. Using cyclotron-produced
fast neutrons in the investigated energy range, sodium and magnesium can also interfere, but only to a very much lower extent. 相似文献
2.
A 14 MeV neutron activation analysis system is described that is being used primarily to determine trace levels of oxygen
in metals. No sample container is required for relatively inert solid metal samples thus increasing the sensitivity of the
method by a factor of five. Under these conditions the sensitivity and precision foroxygen is about 6±3.3 μg in a single determination,
resulting from collecting 1.216N counts per μg of oxygen. A method is described for calibrating the system for the analyses of large metal samples. The preparation
and use of sample containers for the analyses of particulate and/or reactive samples is also presented.
Work was performed at the Ames Laboratory of the U.S. Atomic Energy Commission. Contribution No. 2567. 相似文献
3.
Three variants of oxygen determination differing in their programs of activation and measuring are presented. The high energetic
β-radiation of16N produced by16O(n, p)16N was detected by a Cerenkov-counter with scintillator of Piacryl (Lucite). Standard deviation and sensitivity of the three
variants were investigated. Sensitivity in interference free samples amounts to 4 000 counts/mg of oxygen and the threshold
of detection to 10 μg of oxygen. If the contents of oxygen is more than 1 mg, the standard deviation will be 1.25%.
相似文献
4.
W. D. James W. D. Ehmann C. E. Hamrin L. L. Chyi 《Journal of Radioanalytical and Nuclear Chemistry》1976,32(1):195-205
The feasibility of using fast neutron (14 MeV) activation analysis techniques for the determination of oxygen and nitrogen
in coal has been investigated. Conditions that favor instrumental neutron activation analysis (INAA) include the absence of
problems associated with sample dissolution and the capability of extremely rapid analyses as compared to older techniques
such as the Kjeldahl method for nitrogen. Most previous oxygen determinations have been by difference after major component
analyses. In the present study, oxygen was determined in sized coal and its low temperature ash (LTA) with the difference
representing the organic oxygen content. Both the oxygen and nitrogen analyses employ a multiscaling technique with the former
based on the16O(n, p)16N reaction, while the latter utilizes the annihilation radiation produced by the product of the14N(n, 2n)13N reaction. The high-energy gamma-radiation associated with the decay of16N was essentially free of spectral interferences for coal analysis, although fluorine could cause a primary interference if
the F/O ratio exceeds 0.02. In the nitrogen work, experiments were performed to determine correction factors to account for
the effects of the12C(p, γ)13N and13C(p, n)13N “knock-on” reactions and the39K(n, 2n)38K reaction which produce interfering β+ emitting radionuclides. Data are presented for oxygen in Western Kentucky No. 9 and No. 11 coal and coal ash and for nitrogen
in eleven different coals. 相似文献
5.
G. J. Stock Jr. E. A. Schweikert 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(1):117-126
A novel method for the characterization of metal containing biological compounds has been developed which utilizes both nuclear
activation [e.g.,12C(3He, α)11C] and atomic activations (X-ray emission) induced by 8 MeV3He bombardment. Detection limits for carbon (≈1 μg), oxygen (≈1μg), and metals (1 to 10 ng for elements between P and Zn)
were obtained under routine experimental conditions. The metal stoichiometry of six different compounds (alkaline phosphatase,
amylase, carbonic anhydrase, diamine oxidase, my oglobin, vitamin B12) were determined with typical relative precisions of ±25% for a 40 μg sample. A comparison of these ratios with carbon and
metal measurements obtained by other methods showed a relative accuracy of 1 to 20%. 相似文献
6.
G. Beurton 《Journal of Radioanalytical and Nuclear Chemistry》1983,77(1):123-139
N, O, F, P, S, Cl can be mixed with aluminium during electrolysis, alloying operations and surface treatments. These elements
allow changes in mechanical properties. We have adapted separation methods to neutron activation analysis of aluminium alloys
down to the sub—ppm level. N, F, Cl, determinations need distillation. S and P separations are based on liquid extraction.
O determination is carried out by instrumental method. Tracers and inactive carriers are used for separation study. Clearning
of the surface is performed if necessary. 14 MeV neutron activation is applied to nitrogen, oxygen and fluorine determination.
The sensitivity is about 200 imp/min/mg. Reactor neutron activation is performed for phosphorus, sulfur and chlorine analysis.
The detection level is 0.1 μg/g. Interesting differences of N, O, F, and Cl contents are observed for Al−Zn or Al−Cu alloys
in the range 0.1–10 μg/g. 相似文献
7.
T. Nozaki M. Iwamoto K. Usami K. Mukai A. Hiraiwa 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(2):449-459
Oxygen in silicon nitride films on silicon wafers was analyzed by activation with the16O(3He, p)18F reaction. By3He bombardment of samples propertly arranged under consideration of the18F recoil effect, total oxygen was reliably determined and its predominant part was estimated to be located whether on film
surface, in film interior, or on film-substrate interface. Sample films with 0.1 to 2 μm thicknesses were found to contain
0.2 to 2 μg/cm2 of oxygen in locations varying with preparation conditions. This method has been compared with ESCA and other methods for
surface analysis. 相似文献
8.
Determination of cadmium in water samples by graphite furnace atomic absorption spectrometry after cloud point extraction 总被引:3,自引:0,他引:3
The formation of a complex with 2-(5-brom-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP) and cloud point extraction have
been applied to the preconcentration of cadmium followed by its determination by graphite furnace atomic absorption spectrometry
(GFAAS) using octylphenoxypolyethoxyethanol (TritonX-114) as surfactant. The chemical variables affecting the separation were
optimized. At pH 7.0, preconcentration of only 10 mL of sample in the presence of 0.05% TritonX-114 and 2.5 × 10−6 M 5-Br-PADAP enabled the detection of 0.04 μg/L cadmium. The enrichment factor was 21 for cadmium. The regression equation
was A = 0.0439C(μg/L) + 7.2 × 10−3. The correlation coefficient was 0.9995. The precision for 10 replicate determinations at 10 μg/L Cd was 2.7% relative standard
deviation (RSD). The proposed method has been applied to the determination of cadmium in water samples.
The text was submitted by the authors in English. 相似文献
9.
Alaa S. Amin Ibrahim S. Ahmed Hassan A. Dessouki Hassan A. Mohamed 《Chemical Papers》2010,64(3):278-284
Simple and rapid spectrophotometric methods have been developed for the microdetermination of fluoxetine HCl. The proposed
methods are based on the formation of ion-pair complexes between fluoxetine and bromophenol blue (BPB), bromothymol blue (BTB),
bromocresol green (BCG), and bromocresol purple (BCP) which can be measured at optimum λmax. Optimization of reaction conditions was investigated. Beerșs law was obeyed in the concentration ranges of 0.5–8.0 μg mL−1, whereas optimum concentration as adopted from the Ringbom plots was 0.7–7.7 μg mL−1. The molar absorptivity, Sandell sensitivity, and detection limit were also calculated. The most optimal and sensitive method
was developed using BCG. The correlation coefficient was 0.9988 (n = 6) with a relative standard deviation of 1.25, for six determinations of 4.0 μg mL−1. The proposed methods were successfully applied to the determination of fluoxetine hydrochloride in its dosage forms and
in biological fluids (spiked plasma sample) using the standard addition technique. 相似文献
10.
An evaluation of the sensitivity of mercury and cadmium determinations in large volumes of water is presented. A 10-μg252Cf source immersed in the water sample served as a neutron source. The (n, γ) reaction on hydrogen and the inelastic scattering
from oxygen produced a background count rate that limited sensitivity. A lower limit of 20 ppm for both mercury and cadmium
was found. The procedures described here can be applied to most of the other heavy metals.
Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation. 相似文献
11.
A. Turos L. Wieluński A. Barcz J. Oleński 《Journal of Radioanalytical and Nuclear Chemistry》1973,16(2):627-636
Conclusions The nuclear reaction from low-energy deuteron-bombardment has proved to be a valuable tool for surface oxide layer examination.
Using the16O(d, p)17O and16O(d, α)14N reactions, some important properties of Si−SiO2 structures, such as total number of oxygen nuclei and oxygen concentration profile, can be determined in one measurement
with an accuracy of several percent, within one hour.
Some effects of oxygen deficiency in SiO2 layers of thicknesses exceeding 6000 ? have been found. A more detailed study of this effect will be the subject of forth-coming
experiments. 相似文献
12.
Summary A reversed-phase ion-pair chromatographic (RPIPC) method withN,N,N′, N′-ethylenediaminetetrakis(methylenephosphonic acid) (EDTMP) as coordinating agent has been developed for simultaneous separation
and detection of Cu(II), Fe(III), and Pb(II) ions. Response is linearly dependent on amount of sample over the range 9.52–50.8
μg mL−1 for Cu(II), 8.31–41.8 μg mL−1 for Fe(III), and 37.3–51.8 μg mL−1 for Pb(II). The method has been applied successfully to an artificial mixed-ore sample. 相似文献
13.
Protein can greatly enhance the fluorescence of curcumin (CU) in the presence of sodium dodecyl benzene sulfonate (SDBS).
Experiments indicate that under the optimum conditions, the enhanced intensity of fluorescence is proportional to the concentration
of proteins in the range of 0.0050–20.0 μg mL−1 for bovine serum albumin (BSA), 0.080–20.0 μg mL−1 for human serum albumin (HSA), and 0.040–28.0 μg mL−1 for egg albumin (EA). Their detection limits (S/N=3) are 1.4 ng mL−1, 20 ng mL−1, and 16 ng mL−1, respectively. The method has been satisfactorily used for the determination of proteins in actual samples. In comparison
with most of fluorimetric methods, this method is quick and simple, has high sensitivity and good stability. The interaction
mechanism is also studied. 相似文献
14.
Popp M Hann S Mentler A Fuerhacker M Stingeder G Koellensperger G 《Analytical and bioanalytical chemistry》2008,391(2):695-699
A novel method employing high-performance cation chromatography in combination with inductively coupled plasma dynamic reaction
cell mass spectrometry (ICP–DRC–MS) for the simultaneous determination of the herbicide glyphosate (N-phosphonomethylglycine) and its main metabolite aminomethyl phosphonic acid (AMPA) is presented. P was measured as 31P16O+ using oxygen as reaction gas. For monitoring the stringent target value of 0.1 μg L−1 for glyphosate, applicable for drinking and surface water within the EU, a two-step enrichment procedure employing Chelex
100 and AG1-X8 resins was applied prior to HPIC–ICP–MS analysis. The presented approach was validated for surface water, revealing
concentrations of 0.67 μg L−1 glyphosate and 2.8 μg L−1 AMPA in selected Austrian river water samples. Moreover, investigations at three waste water-treatment plants showed that
elimination of the compounds at the present concentration levels was not straightforward. On the contrary, all investigated
plant effluents showed significant amounts of both compounds. Concentration levels ranged from 0.5–2 μg L−1 and 4–14 μg L−1 for glyphosate and AMPA, respectively. 相似文献
15.
A novel kinetic spectrofluorimetric method for the determination of uric acid based on the activation effect of uric acid
on the Cu(II) ion catalyzed oxidation of pyronine Y by hydrogen peroxide was developed. The influence of different buffer
solutions was tested and the Britton-Robinson buffer solution with pH 2.2 was found to be the optimum. The detection limit
and the linear range for uric acid are 0.09 μg mL−1 and 0.3–3.0 μg mL−1, respectively. The RSD for eleven determinations of 1.6 μg mL−1 uric acid was 1.6 %. Satisfactory results were obtained when using this method of uric acid determination in human urine. 相似文献
16.
A fully automated method using direct immersion solid-phase microextraction (DI-SPME) and headspace on-fiber silylation for
simultaneous determinations of exogenous endocrine-disrupting chemicals (EDCs) and endogenous steroid hormones in environmental
aqueous and biological samples by gas chromatography–mass spectrometry (GC-MS) was developed and compared to a previously
reported manual method. Three EDCs and five endocrine steroid hormones were selected to evaluate this method. The extraction
and derivatization time, ion strength, pH, incubation temperature, sample volume, and extraction solvent were optimized. Satisfactory
results in pure water were obtained in terms of linearity of calibration curve (R
2=0.9932–1.0000), dynamic range (3 orders of magnitude), precision (4–9% RSD), as well as LOD (0.001–0.124 μg L−1) and LOQ (0.004–0.413 μg L−1), respectively. These results were similar to those obtained using a manual method, and moreover, the precision was improved.
This new automated method has been applied to the determinations of target compounds in real samples used in our previous
study on a manual SPME method. Exogenous octylphenol (OP), technical grade nonylphenol (t-NP), and diethylstilbestrol (DES) were at 0.13, 5.03, and 0.02 μg L−1 in river water and 3.76, 13.25, and 0.10 μg L−1 in fish serum, respectively. Natural steroid hormones estrone (E1), 17β-estradiol (E2), and testosterone (T) were at 0.19, 0.11, and 6.22 μg L−1 in river water; and in female fish serum E1, E2, and pregnenolone (PREG) were at 1.37, 1.95, and 6.25 μg L−1, respectively. These results were confirmed by the manual method. The developed fully automated SPME and on-fiber silylation
procedures showed satisfactory applications in environmental analysis and the performances show improved precision and a reduced
analysis time compared to the manual method. 相似文献
17.
There is an increasing need to assess the harmful effects of heavy-metal-ion pollution on the environment. The ability to
detect and measure toxic contaminants on site using simple, cost effective, and field-portable sensors is an important aspect
of environmental protection and facilitating rapid decision making. A screen-printed gold sensor in a three-electrode configuration
has been developed for analysis of lead(II) by square-wave stripping voltammetry (SWSV). The working electrode was fabricated
with gold ink deposited by use of thick-film technology. Conditions affecting the lead stripping response were characterised
and optimized. Experimental data indicated that chloride ions are important in lead deposition and subsequent analysis with
this type of sensor. A linear concentration range of 10–50 μg L−1 and 25–300 μg L−1 with detection limits of 2 μg L−1 and 5.8 μg L−1 were obtained for lead(II) for measurement times of four and two minutes, respectively. The electrodes can be reused up to
20 times after cleaning with 0.5 mol L−1 sulfuric acid. Interference of other metals with the response to lead were also examined to optimize the sensor response
for analysis of environmental samples. The analytical utility of the sensor was demonstrated by applying the system to a variety
of wastewater and soil sample extracts from polluted sites. The results are sufficient evidence of the feasibility of using
these screen-printed gold electrodes for the determination of lead(II) in wastewater and soil extracts. For comparison purposes
a mercury-film electrode and ICP–MS were used for validation. 相似文献
18.
Differentiation of certified brands of origins of Spanish white wines by HS-SPME-GC and chemometrics 总被引:1,自引:0,他引:1
Jurado JM Ballesteros O Alcázar A Pablos F Martín MJ Vilchez JL Navalón A 《Analytical and bioanalytical chemistry》2008,390(3):961-970
A headspace solid-phase microextraction gas-chromatographic (HS-SPME-GC) procedure was used to determine the composition of
the volatile fraction of white wine samples from several Spanish certified brands of origin (CBO). The compounds present were
previously identified by gas chromatography−mass spectrometry (GC−MS) and quantitative determinations were carried out by
GC-FID. Four CBO, Rueda, Ribeiro, Penedés, and Condado de Huelva, were studied. Rueda wines present the highest concentrations
of ethyl acetate (55.86−125.27 μg mL−1), isoamyl acetate (0.91−6.72 μg mL−1), hexyl acetate (0.09−0.81 μg g mL−1), and 2-phenethyl acetate (0.14−0.66 μg mL−1). Compounds such as ethyl hexanoate (0.88−2.15 μg mL−1) and ethyl decanoate (0.29−0.96 μg mL−1) appeared in higher concentration in Ribeiro, Rueda, and Penedés samples. According to the results obtained and by applying
pattern-recognition procedures differentiation of the considered CBO was attained. Principal-component analysis (PCA), linear
discriminant analysis (LDA), and multilayer perceptrons neural networks (MLP-NN) were used as chemometric tools for pattern-recognition
studies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Summary An ion-chromatographic procedure is described for the determination of selenium (VI) at μg L−1 level in the presence of anions and heavy metal ions. Maximum permissible concentrations and effects from each interfering
substance were investigated for the Se concentration range 12.5–1,000 μg L−1. The method, optimized for the detection of SeO
4
2−
, gives results suitable for speciation analysis. Total selenium can be determined after complete conversion to selenate ion
by oxidation with KMnO4. The detection limit of selenium is 4.8 μg L−1 (0.96 ng for 200 μL sample).
Paper presented at the 41st Pittsburgh Conference, New York, March 5–9, 1990. 相似文献
20.
M. A. Taher A. Mostafavi S. Z. Mohammadi Mobarakeh 《Journal of Analytical Chemistry》2007,62(11):1022-1027
This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium
is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5
to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO)
and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the
final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution
with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve
is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996.
Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d
3
A/dλ3 (peak-to-peak signal between λ2 = 625 and λ1 = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d
3
A/dλ3) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and
cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in
various synthetic and water samples.
The text was submitted by the authors in English. 相似文献