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1.
Precise boron isotope ratio measurements with negative thermal ionization mass spectrometry were used for the identification
of ground water contaminations by leakages of landfills. BO-
2thermal ions were produced to determine the 11B/10B isotope ratio, which was expressed as δ11B value in ‰ normalized to the standard reference material NIST SRM 951. For example, household waste influences the boron
isotope ratio by specific components such as washing powder. In the case of one investigated landfill low δ11B values correlate well with high boron concentrations in contaminated seepage water samples and vice versa for uncontaminated
ground water samples. Possible boron contributions of rainwater were taken into account, determining a boron content of 2.3
μg/L and a δ11B value of 13.1‰ for a representative sample. Such low boron concentrations were determined by isotope dilution mass spectrometry
(detection limit 0.3 μg/L) whereas higher contents were also analyzed by a spectrophotometric method. However, different sources
of contamination could only be identified by the isotope ratio and not by the concentration of boron.
Received: 9 December 1996/Accepted: 18 February 1997 相似文献
2.
K. Shikano K. Masumoto T. Ohtsuki M. Katoh 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):75-82
We studied the production of nine typical organic analytical reagents labeled with11C,13N and18F by irradiation with charged particles and bremsstrahlung and the purification of labeled compounds with HPLC and sublimation.
As a result, we found that six reagents, α-naphthol, β-naphthol, quinoline, α-nitroso-β-naphthol, 8-hydroxyquinoline, and
1,10-phenanthroline H2O could be labeled with11C by bombarding a mixture of each reagent and boron with protons. More than 10% of the11C was successfully exchanged with carbon atoms in the original reagents. We also found that sublimation is useful for purifying
8-hydroxyquinoline labeled with11C. The extraction property of11C-labeled 8-hydroxyquinoline between water and chloroform could be easily monitored by radioactivity measurement. 相似文献
3.
I. S. Giles C. Olivier M. Peisach 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):141-154
A survey of the possibilities of analysis by alpha-induced prompt gamma-ray spectrometry is reported for 57 elements at a
bombarding energy of 5 MeV. Additional data obtained at 11 and 16 MeV are given. Interference-free sensitivities are presented.
The use of the position sensitive detector is introduced to overcome problems such as occur in prompt alpha spectrometry from
(p, α) reactions. The technique is illustrated by studies on the reaction19F(p, α)16O and severely tested for boron analysis using the reaction11B(p, α)8Be and measuring the α0 and α1 groups. 相似文献
4.
The determination of boron in sedimentary rocks by neutron irradiation and prompt γ-ray spectrometry
S. A. Kerr W. V. Prestwich T. J. Kennett D. M. Shaw 《Journal of Radioanalytical and Nuclear Chemistry》1980,57(2):525-533
Prompt γ-rays following the (nth, α) reaction on10B have been measured to determine the boron content of sedimentary rocks. Employing an external reactor neutron beam with
only modest flux, it is possible to assay boron at concentrations typically encountered in this material (>5 μg/g). The technique
relies on the use of chemical standards and the values obtained for 9 North American shales are compared with measurements
performed by emission spectrography. Detection limits and statistical errors as a function of beam time are also discussed.
Department of Geology, Mcmaster University, Hamilton, Ontario (Canada) 相似文献
5.
B. Wiedemann G. R?dlinger H. Ch. Alt K. G. Heumann K. Bethge 《Fresenius' Journal of Analytical Chemistry》1999,364(8):772-776
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity
coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For
boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
6.
B. Wiedemann G. Rädlinger H. Ch. Alt K. G. Heumann K. Bethge 《Analytical and bioanalytical chemistry》1999,364(8):772-776
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity
coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For
boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
7.
Thermal conversions of chitosanium dodecahydro-<Emphasis Type="Italic">closo</Emphasis>-dodecaborate
V. I. Saldin L. N. Ignat’eva Yu. M. Nikolenko V. M. Buznik Yu. M. Mikhailov 《Russian Journal of Inorganic Chemistry》2010,55(8):1221-1227
The thermal behavior of chitosanium dodecahydro-closo-dodecaborate, (C6O4H9NH3)2B12H12, was studied by thermal analysis, X-ray diffraction, and IR and X-ray photoelectron spectroscopy. As this compound is heated
at a rate above 10–20 K/min, it ignites at a temperature of about 300°C. As the compound is heated to 1000°C at a rate below
10 K/min in an inert atmosphere, it yields a mixture of carbon and amorphous boron and/or boron carbides. The presence of
a small amount of boron oxide in the product is explained by the formation of a partially oxidized hydroborate anion at the
early stages of (C6O4H9NH3)2B12H12 decomposition via the interaction between oxygen of the chitosanium cation and the B12H122− anion. Heating the initial compound in air at a rate below 10 K/min yields carbon and boron oxide as the main products. Molten
boron oxide protects boron and/or boron carbides and boron nitride forming in small amounts in the particle bulk from oxidation. 相似文献
8.
An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water 总被引:1,自引:0,他引:1
XIAO Yingkai LI Shizhen WEI Haizhen SUN Aide ZHOU Weijian & LIU Weiguo . Qinghai Institute of Salt Lakes Chinese Academy of Sciences Xining China . State Key Laboratory of Loess Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China 《中国科学B辑(英文版)》2006,49(5):454-465
Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally. The results show the clear positive relationships between boron concentration and δ11B of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH)4- is the dominant spe-cies incorporated into the biogenic calcite structure. The isotopic fractionation factors α between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH)3 species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH)3 is attributed to the formation of Mg(OH)2 at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH)2 precipitated from artificial seawater shows that heavier 11B is enriched in Mg(OH)2 precipitation, which suggests that isotopically heavier B(OH)3 species incorporated preferentially into Mg(OH)2 precipitation. This result cannot be applied to explain the boron isotopic fractionation of marine bio-carbonate because of the possibility that the unusual environment in this study appears in formation of marine bio-carbonate is infinitesimal. We, however, must pay more attention to this phenomenon observed in this study, which accidentally appears in especially natural environment. 相似文献
9.
K. Shikano A. Mori M. Shimizu T. Ohtsuki H. Yuki K. Masumoto 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):211-216
Summary We have studied the photon activation analysis of carbon in InF3-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix
produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of 11C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in
these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion
of 11C into 11CO2, and the absorption of 11C in ethanolamine solution. We used a mixture of Pb3O4 and B2O3 as the oxidizer. There is interference with the 11C measurement because 18F and 68Ga are produced in fluoride and chalcogenide glasses by the 19F(γ,n), 23Na(γ,αn) and 69Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied
to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese
Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the
carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm. 相似文献
10.
V. K. Kochnev V. V. Avdeeva L. V. Goeva E. A. Malinina N. T. Kuznetsov 《Russian Journal of Inorganic Chemistry》2012,57(3):331-336
Using the electron density functional theory (B3LYP approximation) with the 6-31G* basis set, the potential energy surface
of the undecahydrodecaborate anion B10H11− was calculated and the activation energies and the activation barriers for the elementary reactions of proton H* migration
around the boron polyhedron were estimated. Analysis of the calculation results in comparison with the experimental data accumulated
recently implies that the salts of the B10H11− anion represent a new type of starting compounds for exopolyhedral substitution and complexation involving decaborate anions.
Of particular interest is the targeted preparation of isomers of metal complexes containing a decaborate anion depending on
the use of B10H102− or B10H11¨- as the starting reagent. Certain trends in the reactivity of B10H10− and B10H11− anions can be explained in terms of the simple analysis of Mulliken charge distribution on atoms. 相似文献
11.
H. Kühne A. Fischer T. Morgenstern D. Grützmacher 《Journal of Solid State Electrochemistry》1998,2(4):273-280
The effect of boron incorporation during chemical vapor deposition of SiGe thin films from silane, germane, diborane, and
hydrogen gas mixtures is investigated. It is shown that boron incorporation during SiGe thin-film growth degrades the Ge profile
under certain growth conditions when the boron concentration is high enough (>1019 cm−3). In single-wafer atmospheric-pressure processes we find that no Ge concentration depression occurs at deposition temperatures
above 675 °C. In multi-wafer atmospheric-pressure processes we find an increasingly occurring depression of the Ge concentration
along the wafer stack, even at temperatures above 675 °C. In low-pressure processes, high-level in-situ doping of SiGe with
boron is possible at temperatures as low as 550 °C without any degradation of the Ge profile. Thus LPCVD is superior to APCVD
with respect to high-level in situ doping of SiGe with boron. The presence or absence of Ge profile degradation in boron-doped
SiGe thin films is explained by the discussion of growth rate enhancement phenomena.
Received: 15 September 1997 / Accepted: 7 November 1997 相似文献
12.
P. S. Ramanjaneyulu K. L. Ramakumar Y. S. Sayi 《Accreditation and quality assurance》2010,15(12):665-671
Boron doped zirconium–niobium alloy is employed for neutron reactivity control in advanced nuclear reactors. An accurate knowledge
of the boron content and uncertainty associated with the measurement result is essential for reactivity calculations. In view
of the refractory nature of the alloy, boron determination in these matrices is a challenging task for analytical chemists.
Also due to non-availability of matrix-matched reference materials, direct solid analysis cannot be resorted to. With this
in view, a simple and sensitive method based on potentiometric determination of boron as tetrafluoroborate with tetrafluoroborate
ion selective electrode has been developed. After dissolving the sample, boron was quantitatively converted to BF4
− with the addition of HF. Potential response was measured with Orion 9305 BN BF4
− ion selective electrode. The response of the ion selective electrode was Nernstian in the range of 0.1–100.0 μg/g of boron
in the solution. The method has been validated by two independent methods namely spectrophotometry and inductively coupled
plasma-atomic emission spectrometry (ICP-AES). All identifiable sources of uncertainties in the methodology have been individually
assessed. The combined uncertainty is calculated employing uncertainty propagation law. The expanded relative uncertainty
in the measurement (coverage factor 2) is 6.50%. 相似文献
13.
The structural analysis of three boron compounds, boron carbide (B4C), silicon tetraboride (SiB4) and hexagonal-boron nitride (h-BN), were performed using 2D 11B-triple quantum MAS (3QMAS) solid state NMR capable of averaging the second-order quadrupolar interaction of 11B that cause line broadening, splitting and low frequency shift of the central transition (−1/2, 1/2). The coordination number around the boron atom and structural symmetry of each boron compound is discussed by means of the isotropic chemical shift Δσ and the quadrupolar coupling constant CQ calculated from 3QMAS spectra. Δσ of SiB4 is quite larger than that of B4C, which is thought to be caused by its structural distortion and distribution. Δσ of h-BN was found to be higher frequency shift obviously than that of B4C and SiB4 because of the difference of the boron coordination number, three-coordinated in h-BN and six-coordinated in B4C and SiB4. h-BN has very large CQ compared to other two boron compounds since the h-BN forming a two-dimensional network has less structural symmetry than B4C and SiB4. 相似文献
14.
Comparative quantum chemical calculations of structural parameters, chemical shifts of 11B NMR spectra, and atomic charges in 10-vertex boron hydride anions [1-CB9H10]− and [1-B10H9N2]− were performed using the restricted Hartree-Fock method with the 6-31++G(D,P) basis set.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1853–1855, September, 2007. 相似文献
15.
S. S. Akimov E. Yu. Matveev G. A. Razgonyaeva L. I. Ochertyanova N. A. Votinova K. Yu. Zhizhin N. T. Kuznetsov 《Russian Chemical Bulletin》2010,59(2):371-373
A new method for the synthesis of oxonium derivatives of the closo-decaborate anion in high yields was described. Reactions of the anion B10H10
2− with cyclic ethers (tetrahydrofuran (THF) and tetrahydropyran) in the presence of dry HCl are stepwise processes. Depending
on the reaction temperature and time, either mono- or disubstituted products were obtained. Their structures were determined
using 11B, 13C, and 1H NMR and IR spectroscopy, ESI mass spectrometry, and elemental analysis for boron. 相似文献
16.
P. Bock Ch. Engelmann A. Hatterer 《Journal of Radioanalytical and Nuclear Chemistry》1977,38(1-2):97-106
Carbon and nitrogen are determined by means of the photonuclear reactions:12C(γ n)11C and14N(γ, n)13N. This article presents a simultaneous chemical separation method for the isolation of11C and13N. It is based mainly on combustion of the sample, after irradiation and etching, in a mixture of oxidising acid fused salts
(B2O3 and Pb3 O4) containing a dispersing agent (NaCl and KCl) and the respective carriers. Each analysis takes about 40 min altogether. Minimum
carbon and nitrogen contents of a few 10−2 μg·g−1 can be measured. The influence of the main competitive nuclear reactions on neighbouring elements, including the sodium itself,
is examined. 相似文献
17.
Laure Aimoz Enzo Curti Urs Mäder 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):517-524
129I is one of the major dose-determining nuclides in the safety analysis of deep storage of radioactive waste. Iodine forms
anionic species that hardly sorb on the surfaces of common host-rock minerals. Recently, interest has arisen on the role of
pyrite, an accessory mineral capable of binding anionic selenium. Whereas the interaction of selenium with pyrite is well
documented, corresponding results on iodine sorption are still scarce and controversial. Pyrite is present in argicilleous
rocks which are being considered in many countries as potential host rocks for a radioactive waste repository. The uptake
of iodide (I−) on natural pyrite was investigated under nearly anoxic conditions (O2 < 5 ppm) over a wide concentration range (10−11–10−3 M total I−) using 125I as the radioactive tracer. Weak but measurable sorption was observed; distribution coefficients (R
d) were less than 0.002 m3 kg−1 and decreased with increasing total iodide concentration. Iodide sorption was connected to the presence of oxidized clusters
on the pyrite surface, which were presumably formed by reaction with limited amounts of dissolved oxygen. The results obtained
indicated that pyrite cannot be considered as an effective scavenger of 129I under the geochemical conditions prevailing in underground radioactive waste geologic storage. 相似文献
18.
Jelena S. ?or?evi? Ana M. Kalijadis Ksenija R. Kumri? Zoran M. Jovanovi? Zoran V. Lau?evi? Tatjana M. Trti?-Petrovi? 《Central European Journal of Chemistry》2012,10(4):1271-1279
In this study the application of home-made unmodified (GC) and bulk modified boron doped glassy carbon (GCB) electrodes for the voltammetric determination of the linuron was investigated. The electrodes were synthesized with a moderate temperature treatment (1000°C). Obtained results were compared with the electrochemical determination of the linuron using a commercial glassy carbon electrode (GC-Metrohm). The peak potential (E p ) of linuron oxidation in 0.1 mol dm−3 H2SO4 as electrolyte was similar for all applied electrodes: 1.31, 1.34 and 1.28 V for GCB, GC and GC-Metrohm electrodes, respectively. Potential of linuron oxidation and current density depend on the pH of supporting electrolyte. Applying GCB and GC-Metrohm electrodes the most intensive electrochemical response for linuron was obtained in strongly acidic solution (0.1 mol dm−3 H2SO4). Applying the boron doped glassy carbon electrode the broadest linear range (0.005–0.1 μmol cm−3) for the linuron determination was obtained. The results of voltammetric determination of the linuron in spiked water samples showed good correlation between added and found amounts of linuron and also are in good agreement with the results obtained by HPLC-UV method. This appears to be the first application of a boron doped glassy carbon electrode for voltammetric determination of the environmental important compounds. 相似文献
19.
K. Strijckmans C. Vandecasteele M. Esprit 《Fresenius' Journal of Analytical Chemistry》1980,303(2):106-110
Summary The determination of boron, carbon, nitrogen and oxygen in nickel by charged particle activation using the reactions 10B(d, n)11C, 12C(d, n)13N, 14N(p, )11C and 16O(3He, p)18F is studied. The interference of 11B(p, n)11C with the 14N(p, )11C reaction is taken into account. 11C, 13N and 18F are separated by oxygen combustion followed by trapping of 11CO2 in NaOH and by steam distillation of 13NH3 and of H2Si18F6, respectively. The results obtained were 0.129±0.035 g g–1 for boron, 86.4±8.3 g g–1 for carbon, 1.077±0.037 g g–1 for nitrogen and 8.91±1.00 g g–1 for oxygen. The results for nitrogen and oxygen agreed satisfactorily with those of other analytical methods.Grateful acknowledgement is made to Prof. J. Hoste for his interest shown in this work, to J. Pauwels (B.C.M.N., Geel) for providing the samples, to B. F. Schmitt (Bundesanstalt für Materialprüfung, Berlin) for helpful information concerning the radiochemical separation of 11C and to the NFWO and the IIKW for financial support. 相似文献