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1.
A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10−3 μg Cr. Dried blood was irradiated with a neutron flux of 1012 n·cm−2·sec−1 in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid.
The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of51Cr. In order to make correction for the interfering reaction54Fe(n,α)51Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between
1.03×10−2 and 5.2×10−2 ppm Cr. 相似文献
2.
Adsorption behavior of rice husk for the decontamination of chromium from industrial effluents 总被引:2,自引:0,他引:2
N. Khalid A. Rahman S. Ahmad A. Toheed J. Ahmed 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(3):775-781
Rice husk, an agricultural waste product, was studied as a potential decontaminant for chromium in the effluents of leather
tanning industries. Physico-chemical parameters such as selection of appropriate electrolyte, shaking time, concentration
of adsorbent and adsorbate were studied to optimize the best conditions in which this material can be utilized on commercial
scale for the decontamination of effluents. The radiotracer technique was used to determine the distribution of chromium.
In certain cases atomic absorption spectrophotometry was also employed. Maximum adsorption was observed at 0.01 mol·dm−3 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 3.0 g of adsorbent for 2.73·10−3 mol·dm−3 chromium concentration in five minutes equilibration time. Studies show that the adsorption decreases with the increase in
the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 2.73·10−3 to 2.73·10−2 mol·dm−3 chromium concentration. The characteristic Freundlich constants, i.e., 1/n=0.86±0.06 andA=2.35±0.06 mmol·g−1 have been computed for the sorption system. Thermodynamic parameters, i.e., ΔG
0, ΔS
0 and ΔH
0 have also been calculated for the system. Application of the method to a test case of a medium size industry showed that
21 kg of rice husk was sufficient to maintain the NEQS limits of chromium for industrial effluents. 相似文献
3.
C. Papadopoulou G. Kanias I. Hadzistelios 《Journal of Radioanalytical and Nuclear Chemistry》1976,31(2):389-396
A simple ion exchange procedure has been developed for the separation of chromium from the other chemical elements in biological
tissues. This procedure combined with neutron activation analysis has been applied successfully to the determination of chromium
in a reference biological material. The precision was ±11%, the accuracy 3% and the sensitivity found was 10 ng with only
20 hrs irradiation at 2.8·1013 n·cm−2·sec−1 flux The main steps of the procedure are: wetdigestion of the irradiated tissue, oxidation to chromium (VI), fixation onto
an anion resin in sulfate form, washing of the resin with 1N H2SO4, collection of chromium by reductive elution for counting and finally determination of the chemical yield by reactivation. 相似文献
4.
The electrochemical behavior of the ofloxacin–copper complex, Cu(II)L2, at a mercury electrode, and the interaction of DNA with the complex have been investigated. The experiments indicate that
the electrode reaction of Cu(II)L2 is an irreversible surface electrochemical reaction and that the reactant is of adsorbed character. In the presence of DNA,
the formation of the electrochemically non-active complexes Cu(II)L2-DNA, results in the decrease of the peak current of Cu(II)L2. Based on the electrochemical behavior of the Cu(II)L2 with DNA, binding by electrostatic interaction is suggested and a new method for determining nucleic acid is proposed. Under
the optimum conditions, the decrease of the peak current is in proportional to the concentration of nucleic acids in the range
from 3 × 10−8 to 3 × 10−6 g · mL−1 for calf thymus DNA, from 1.6 × 10−8 to 9.0 × 10−7 g · mL−1 for fish sperm DNA, and from 3.3 × 10−8 to 5.5 × 10−7 g · mL−1 for yeast RNA. The detection limits are 3.3 × 10−9, 6.7 × 10−9 and 8.0 × 10−9 g · mL−1, respectively. The method exhibits good recovery and high sensitivity in synthetic samples and in real samples. 相似文献
5.
S. Pavelka M. Vobecký A. Babický 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):575-579
The study describes a mode of non-destructive simultaneous determination of bromine and iodine concentrations, by reactor
instrumental neutron activation analysis (INAA) in the regime of short-term activation. Under the conditions of 1-minute activation
in the neutron flux of 8.0·1013 n·cm−2·s−1, it was possible to determine reliably as little as 5·10−8 g bromine and about 10−7 g iodine in matrices of a given type and of the mass of about 5 mg dry weight. We applied this method for the determination
of Br and I concentrations in the whole rat thyroid gland as well as for the halogen speciation in fractions separated from
this organ. 相似文献
6.
The present work deals with study of uptake behavior of zinc and mercury ions by hydrous ceric oxide applying a radiotracer
technique. The influence of various parameters such as concentration, temperature and pH have been examined. It was observed
that the amount of zinc and mercury ions adsorbed at equilibrium increases with increase of adsorptive concentration (1.0·10−7 to 1.0·10−2M), temperature (303–333K) and pH (ca. 3–10). Concentration dependence data agree well with the classical Freundlich isotherm.
The radiation stability of hydrous ceric oxide was also investigated by exposing it to a 11.1 GBq (Ra−Be) source associated
with γ-dose of 1.72 Gy·h−1 and also using a60Co source (4.66 kGy·h−1). Adsorption of these metal ions in the presence of some monovalent and divalent cations and complexing agents has also been
included in the study. 相似文献
7.
B. Vialatte 《Journal of Radioanalytical and Nuclear Chemistry》1971,8(2):269-276
The determination of lithium by measuring7Be, produced by proton or deuteron activation, has been studied. The extent of interference from boron or beryllium, which
also form7Be, was measured. The calculated sensitivity limits when activating for one hour with 10μA beams of 14 MeV protons or 25 MeV
deuterons are, for lithium, 1·10−1 and 2.5·10−2 ppm and for boron, 2·10−1 and 1·10−1 ppm, respectively.
相似文献
8.
I. F. Yazikov N. N. Rodin M. A. Dembrovsky V. G. Lambrev 《Journal of Radioanalytical and Nuclear Chemistry》1969,3(1-2):11-16
A method is described for the radioanalytical determination of traces of chlorine in aqueous solutions without radiochemical
separation or purification. Using a gamma-spectrometer with monocrystal scintillator, the sensitivity of the analysis is about
1·10−8 g of chlorine/ml, the time of analysis being 15 minutes. For the selective determination of chlorine in aqueous solutions
containing a large amount of impurities, a bicrystal scintillation sum-coincidence spectrometer was employed with 120×100
mm NaI(Tl) crystals and thus the38Cl cascade radiation could be used. Application of the sum-coincidence spectrometer allowed a reliable determination of 1·10−7 g of Cl/ml against a background of 1·10−5 g of Na/ml. 相似文献
9.
Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion 总被引:1,自引:0,他引:1
ZHANG Ying SHAO Na YANG Ronghua LI Ke’an LIU Feng CHAN Winghong & MO Tian . College of Chemistry Molecular Engineering Peking University Beijing China . Department of Chemistry Hong Kong Baptist University Hong Kong China 《中国科学B辑(英文版)》2006,49(3):246-255
Spiropyrans are the most studied families of func- tional materials due to their reversible structural con- version in response to external optical, chemical, and thermal stimulation[1]. Irradiation with ultraviolet light causes formation of an extended π-conjugation open form (merocyanine form) by heterolytic cleavage of the C (spiro)-O bond, which generates an intense ab- sorption in the visible region. Under the irradiating of visible light, the opened form will come back to the closed spi… 相似文献
10.
A collimated neutron beam capable of providing a thermal neutron flux of 4.75·107 n·cm−2·sec−1 has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron
capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio
of every constituent present in the matrix with the concentration and thus it requires no standards. The technique was applied
to the analysis of steel and gold alloy samples. Errors ranged from 0.8%–10%. 相似文献
11.
Jinzhang Gao Dongyu Lv Wu Yang Xiaoxia Wei Jie Qu Hua Chen Hongxia Dai Jie Ren 《Central European Journal of Chemistry》2007,5(2):581-589
A convenient and sensitive method for determination of sulfanilamide (SNA) was described based on the Mn(II)-catalyzed oscillating
chemical reaction. Under optimum conditions, a linear relationship existed between the changes of oscillating period or amplitude
and the negative of logarithm of SNA concentration in the range of 4.27 × 10−8 mol ·L−1 ∼ 7.41 × 10−6 mol ·L−1 (RSD, 0.85%) and 9.33 × 10−8 mol ·L−1 ∼ 3.02 × 10−6 mol ·L−1 (RSD, 1.08%), respectively. The lower limit of detection was found to be 2.69 × 10−8 mol ·L−1 and 6.03 × 10−8 mol ·L−1, respectively.
相似文献
12.
Raúl A. Sánchez-Moreno M. Jesús Gismera M. Teresa Sevilla Jesús R. Procopio 《Analytical and bioanalytical chemistry》2010,397(1):331-338
A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis.
The carbon screen-printed electrode was modified with a graphite–epoxy composite. The optimal graphite–epoxy matrix contains
37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal
analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed
sensor exhibits a response time of 20 ± 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour
using 0.1 M NaNO3 solution at pH 3 as the carrier, a flow rate of 2.5 mL·min−1, and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI)
ions and optimal detection limits in both static mode (2.1 × 10−7 M) and online analysis (9.4 × 10−7 M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river
waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful
results in leachates from municipal solid waste landfills. 相似文献
13.
A novel flow injection procedure has been developed for the determination of tannic acid based on the inhibition of the chemiluminescences
in luminol-H2O2-Manganese tetrasulfonatophthalocyanine (MnTSPc) system by tannic acid. The method is simple, rapid and sensitive with a detection
limit of 8 × 10−10 mol·L−1 and a linear range of 7 × 10−9–5 × 10−6 mol·L−1. The relative standard deviation is 1.9% for eleven measurements of 5 × 10−7 mol·L−1 tannic acid. The method has been successfully applied to the determination of tannic acid in real Chinese gall and hop pellets
samples. 相似文献
14.
T. S. Urbański 《Journal of Radioanalytical and Nuclear Chemistry》1974,22(1-2):13-19
The separation of lanthanum from calcium and a number of radioisotopes of other elements by extraction with alkylphosphoric
acids and tri-n-butylphosphate has been studied. A quantitative method has been developed for the separation of a lanthanum
tracer from neutron-irradiated preparations on a calcium carrier, obtained from the steel-making process. This method improves
the detectability of140La (from 5·10−7 to 10−10 g of La) by γ-ray spectrometry with a scintillation counter, and enables semiquantitative determination of lanthanum with
a liquid GM tube, the error involved being about 100% for La contents >10−8 g, and about 30% for La contents >10−7 g. 相似文献
15.
P. Manoj H. Mohan V. M. Manoj J. P. Mittal C. T. Aravindakumar 《Research on Chemical Intermediates》2006,32(9):817-826
Pulse radiolysis has been used to investigate the reaction of hydroxyl radical (·OH) and oxide radical anion (O·−) with 2-aminopurine (2AP), a fluorescent analogue of adenine, in aqueous medium. The second-order rate constant for the reaction
of ·OH with 2AP was determined to be 3 × 109 dm3 mol−1s−1 and for the reaction of O·− it was 7.1 × 108 dm3 mol−1s−1. The transient absorption spectrum obtained in the reaction of ·OH at pH 7 has absorption maxima at 370 and 470 nm. The spectrum undergoes a time-dependent transformation at higher time-scale.
The intermediate species was found to react with N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD). The yield of TMPD·+ was calculated in terms of G(TMPD·+) to be 3.3 × 10−7 mol J−1 at pH 7. The ·OH reactions were also carried out at pH 10 and the transient absorption spectra have λ
max at 400 and 480 nm. The transient spectra obtained in the reaction of O·− at pH ≈14 have maxima at 400 and 480 nm. The transient intermediate species at pH 7 are assigned to the formation of 2AP-4-OH· (54%), 2AP-5-OH· (7%) and 2AP-8-OH· (39%) based on the spectral evidence and TMPD·+ build-up. Both 2AP-4-OH· and 2AP-5-OH· undergo OH− elimination to form a radical cation. At higher pH (pH 10), the dehydration reaction of these OH-adducts leads to a N-centered
radical (2AP-N(9)·, 71%). Formation of 2AP-8-OH· (29%) is also proposed at this pH. In the reaction of O·− with 2AP, it is proposed that a similar nitrogen centered 2AP-N(9)· radical is formed by an electron-transfer reaction at N(9). 相似文献
16.
Irradiation and post-irradiation losses in 7 crude oils encapsulated in polyethylene and irradiated in a flux of 1012n·cm−2 sec−1 have been thoroughly studied. The fraction of mercury released during irradiations ranging from 10 minutes to 2 hours is
proportional to the integrated flux received by the samples and does not differ substantially from one oil to another. Post-irradiation
loss rates at 20°C range between 0.017 and 0.027%·hr−1. Storage at−20°C reduces them by at least a factor of 2. The influence on the activity of197Hg due to losses in sample weight occuring during the post-irradiation period has been examined. The fraction of radiomercury
retained inside the walls of the irradiation vials versus the irradiation time has been assessed. Contamination of an inner
irradiation site following prolonged irradiations of oils containing 150 μg/g of this element has been evaluated and found
to have a negligible impact for trace measurements above the ng/g level. 相似文献
17.
The differential pulse (dp) polarograms of thiamine in neutral aqueous solutions exhibited six peaks at low depolarizer concentration
(⋦10−4 mol dm−3) and only three peaks at concentrations ≥10−3 mol dm−3. Only one of these was found to correspond to the diffusion-controlled reduction of this compound at the dme and this was
shown to be an irreversible two-electron process. The kinetic parameters derived from the dp polarograms were found to be
in good agreement with those calculated from classical polarograms and were:E
1/2=−1·261 Vvs SCE,an
a=0·54 andD≈3·5×10−6 cm2 sec−1 for 10−3 mol dm−3 thiamine in 0·1 mol dm−3 acetate buffer (pH 6·5). The reduction product has been identified as dihydrothiamine. The effect of pH on the dpp of thiamine
was studied in the pH range 0–7. In the pH region 5·5 to 7·0 only one peak attributable to the B1
+ form of thiamine is present. In the pH region 3·5–5·5 another dpp peak attributable to the protonated form (B1H2+) of thiamine was also observed. At pHs less than 3 only one peak was observed which could be attributed to the doubly protonated
form (B1 H2
3+) of thiamine. Surfactants like triton-X-100 and CTABr were found to inhibit the electroreduction of thiamine due to the strong
adsorption of these compounds on the dme. Thiamine itself was found to have an inhibitory effect on its own electroreduction,
although to a smaller extent. 相似文献
18.
K. Pietrucha L. Góra K. Burczak 《Journal of Radioanalytical and Nuclear Chemistry》1998,232(1-2):83-86
Hydroxyl radicals were generated radiolytically in N2O-saturated aqueous solutions of the aminoglycoside antibiotic, gentamycin. Using the pulse radiolysis technique, the rate
constant of OH radicals with gentamycin determined was 1.2·109 dm3·mol−1·s−1. Upon.OH attack a transient species with an absorption maximum at 270 nm is observed which decays by second-order kinetics within
the solute concentration range of 3.2·10−5 to 1·10−3mol·dm−3. Transient species undergoes transformation to a permanent product absorbing between 260 and 340 nm with maximum absorption
at 300 nm. Rate constant of the reaction of bimolecular decay of gentamycin radicals, k (Gen.+Gen.) was found to be ≈ 1.4·107 dm3·mol−1·s−1. 相似文献
19.
A. M. Golubenkov A. F. Malenchenko 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(2):547-556
For the solution of most of the problems which are connected to the biological and physiological role of natural uranium in
plants and animal organisms about 10−14 g uranium should be determined. However most of the physico-chemical methods for the determination of natural uranium in
biomaterials are time-consuming and possess considerable error. On the basis of addition and inner standard methods a version
of Solid State Nuclear Track Detectors (SSNTD) method has been developed in order to determine the natural uranium in biospecimens.
According to the experimental data simple relations have been obtained for the calculation of uranium concentration in biomaterial
and minium uranium concentration in biosolution which can be measured by the detector used. Under irradiation of SSNTD at
a thermal neutron flux of (3–5)·1015n·cm−2 the detector sensitivity is 2.30·10−9 g U/ml for glass detectors; 9.60·10−10g U/ml for the detectors made from artificial mica. 相似文献
20.
W. J. Naudé M. Peisach R. Pretorius P. J. Strebel 《Journal of Radioanalytical and Nuclear Chemistry》1968,1(3):231-241
Carbon, nitrogen and oxygen were determined in gases by time-of-flight spectrometry of prompt neutrons from the respective
reactions12C(d, n)13N,14N(d, n)15O and16O(d, n)17F, produced by a pulsed beam of deuterons of 2 MeV (for nitrogen) or 3 MeV. The analysis is non-destructive and requires about
15 min. per sample. The relative standard deviation for all three elements was about ±3%. Detection limits, using a total
irradiation current of 20 millicoulombs, for carbon, nitrogen and oxygen, respectively, were 6·10−8 g, 2·10−7 g and 1.7·10−7 g per cm2 cross-sectional area of irradiating beam. 相似文献