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1.
The H-point standard addition method (HPSAM) was applied to handling spectrophotometric data for simultaneous determination
of Zn2+ and Cu2+ or selective determination of Zn2+ in the presence of Cu2+. The ligand 1-(2-pyridylazo)2-naphthol (PAN) and its metal complexes (Zn-PAN and Cu(II)-PAN) were made water-soluble by the
neutral surfactant Triton X-100, and therefore, no extraction with organic solvents was required. The method is based on the
difference in absorbance of formed complexes between Zn2+ and PAN, at two different wavelengths at pH = 9.2. The formation of both the complexes was complete within five minutes.
Zn2+ can be determined in the range of 0.2–25 μg/mL with satisfactory accuracy and precision in the presence of excess of Cu2+ and most other metal ions. Interference effects of common anions and cations were studied. Under working conditions, the
proposed method was successfully applied to the simultaneous determination of Zn2+ and Cu2+ in several real and synthetic mixtures with different concentration ratio of Zn2+ and Cu2+.
The text was submitted by the authors in English. 相似文献
2.
A facile, sensitive and rapid spectrophotometric method for the determination of nitrite is presented. The method involves
the reaction of nitrite with 4-aminoazobenzene under acidic conditions in the presence of a bromide ion allowing to complete
the diazotization reaction almost instantaneously. The formed diazonium ion is then coupled with acetyl acetone to give bisazo
dye in an aqueous alkaline medium having maximum absorption at 500 nm. The molar absorptivity and Sandell’s sensitivity of
the method were found to be 4.2 × 104 dm3 mol−1 cm−1 and 1.1 ng cm−2, respectively. The system obeys the Beer’s law within the concentration range of 0.1–9 μg of nitrite in the final sample
volume of 10 cm3. Optimum reaction conditions were evaluated and the influence of ionic interference on the determination of nitrite has been
studied. The developed method has been applied in the determination of nitrite in water and soil samples, and the results
were statistically evaluated. 相似文献
3.
矿化剂浓度对水热法合成氧化锌晶体的影响 总被引:1,自引:0,他引:1
In this paper different shapes of ZnO crystals were synthesized by hydrothermal method when different con-centrations of mineralizer were used. When KOH was less than 2mol·L-1 and the fill factor was approximately 35% at 350℃, ZnO crystals were synthesized with size of several hundred nanometer or several micron. The shapes of crystals were hexagonal cones. When 3mol·L-1 KOH was used as mineralize at 350℃ and the fill factor was approximately 35%, the crystals with many different sizes were synthesized, the size of maximal crystal was over 100 micron, the small-size crystals were only several micron. When mineralizer KOH was less than 1mol·L-1 and the fill factor was approximately 35% at 430℃, ZnO crystals were synthesized with size of several hundred nanometer or several micron. The shapes of crystals were hexagonal cones. When 1.5mol·L-1 KOH or 2mol·L-1 KOH was used as mineralize at 430℃ and the fill factor was approximately 35%, the high quality and hexagonal prism crystals were synthesized with many different sizes, the size of maximal crystal was over 100 mi-cron, the small-size crystal was only several micron. Especially when 3mol·L-1 KOH was used as mineralize at 430℃ and the fill factor was approximately 35%, the high quality and hexagonal prism crystals were synthesized with size of 1mm along c axis. The exposed faces were hexagonal faces m{1010}, hexagonal cone faces p{1011}, negative polar faces O{0001}. In addition, many crystals with the shape of hexagonal cone and in several micron to 50 μm of size were present. The exposed faces were hexagonal cone faces p{1011}, negative polar faces {0001}. 相似文献
4.
Summary A capillary GC/MS method is presented for the analysis of iprodione (CAS registry number 36734-19-7) in chicory and in leek.
Preliminary extraction was carried out using methanol, and the extracts were cleaned up using two liquid-liquid extractions
and Bakerbond SPE Florisil? cartridges. The eluates were evaporated to dryness under reduced pressure, and the residues dissolved
in hexane. Iprodione was then monitored by capillary Gas Chromatography, with Mass Spectrometric Detection, in the selective
ion mode at m/z 314. Recoveries of 89 % to 108 % were obtained for chicory and leek fortified at 100 and 500 μg kg−1. The proposed method of analysis has a detection limit of 2 μg kg−1 for chicory and 4 μg kg−1 for leek. 相似文献
5.
Guogang Jia G. Torri P. Innocenzi R. Ocone A. Di Lullo 《Journal of Radioanalytical and Nuclear Chemistry》2006,267(3):505-514
Summary A method for the determination of low-level radium isotopes in mineral and environmental water samples by alpha-spectrometry
has been developed. Radium-225, which is in equilibrium with its mother 229Th, was used as a yield tracer. Radium were preconcentrated from water samples by coprecipitation with BaSO4and iron (III) hydroxide at pH 8-9 using ammonia solution, then isolated from uranium, thorium and iron using a Microthene-TOPO
chromatography column at 8M HCl, separated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylenedinitrilotetraacetic
acid monohydrate at pH 8.5 as an eluant, and finally electrodeposited on a stainless steel disc in a medium of 0.17M (NH4)2C2O4at pH 2.6 and current density of 400 mA. cm-2, and counted bya-spectrometry. Optimum experimental conditions for radium separation, purification and electrodeposition
have been studied and discussed in the paper. The lower limits of detection of the method are 0.11 mBq. l-1for 226Ra, 228Ra and 224Ra, respectively, if 2 l of water are analyzed. The method has been checked with a certified reference material IAEA-Soil-6
supplied by the International Atomic Energy Agency and reliable results were obtained. Eighteen water samples collected in
Italy have been analyzed with the method, the mean radiochemical yields for radium were 86.2±6.5%. The obtained radium concentrations
were in the range of 0.50-60.8 mBq. l-1for 226Ra, of 0.10-25.7 mBq. l-1for 228Ra, and of£LLD-7.97 mBq. l-1for 224Ra. The 228Ra/226Ra and 224Ra/226Ra ratios were in the range of 0.189-4.45 and£LLD-0.941, respectively. 相似文献
6.
铁、氮共掺杂二氧化钛粉末的制备及光催化活性 总被引:24,自引:0,他引:24
Using TiCl4 as the titanium source, nanoparticles of TiO2 doped with nitrogen(N-TiO2) were synthesized by triethylamine. TiO2 powder codoped with iron and nitrogen(Fe/N-TiO2) were prepared by adsorption-deposition of Fe3+ on N-TiO2 and calcining at 400 ℃ for 2 h. From the XPS results for N1s binding energy at 399.6 eV and 396.6 eV, it is proposed that the partial N atoms as substitution atoms replace for O atoms in TiO2 lattice. The onset of the absorption spectrum of Fe/N-TiO2 has a 45 nm red-shift compared with that of TiO2. The results of photocatalytic degradation of methylene blue solution indicate that Fe/N-TiO2(0.45% Fe3+) has a higher activity. Its photocatalytic activity is about 2 times as high as that of pure TiO2 under UV-light, and 3 times under sunlight. Doping of nitrogen in TiO2 enhances photoresponse in visible light region and doping of Fe3+ reduces the recombination of electrons and holes. Both of the above effects are beneficial for improving the performances of Fe/N-TiO2 photocatalyst. 相似文献
7.
A method using GC-MS and derivatization with N-(t-butyldimethylsilyl)-N-ethyltrifluoroacetamide (MTBSTFA) was developed for the analysis of 19 chlorophenols compounds in atmospheric samples (gas
and particles). Air sampling was carried out using a Hi-Vol sampler with glass fibre filter and XAD-2 resin at a flow rate
of 60 m3 h−1. The particle and gas phases were collected separately over a period of 4 h. Samples were Soxhlet extracted, evaporated to
dryness under nitrogen and refilled with acetonitrile. 100 mL of these extracts were derivatized with 100 μL of MTBSTFA at
80 °C for 1 h under strong stirring. Sylylated chlorophenols were injected into a GC-MS in splitless mode and quantified as
their TBDMS derivatives in the SIM mode. Mass spectral analysis of the derivatives of the 19 compounds studied indicates that
the spectra are highly specific showing an ion at [M - 57]+ which is useful for structure confirmation or analysis at low levels using selected ion monitoring. Quantification limits
varied between 5 μg L−1 and 10 μg L−1 which correspond to 20 pg m−3 and 40 pg m−3 for 250 m3 of air sampled. This method was successfully applied to atmospheric samples collected simultaneously in winter 2004 in an
urban (Strasbourg) and rural (Erstein) areas in east of France. 相似文献
8.
Using integer and noninteger n-Slater type orbitals in single- and double-zeta approximations, the Hartree-Fock-Roothaan calculations were performed for the ground states of first ten cationic members of the isoelectronic series of He atom. All the noninteger parameters and orbital exponents were fully optimized. In the case of noninteger n-Slater type orbitals in double zeta basis sets, the results of calculations obtained are more close to the numerical Hatree-Fock values and the average deviations of our ground state energies do not exceed 2×10-6 hartrees of their numerical results. 相似文献
9.
One titrimetric and two spectrophotometric methods, which are simple, sensitive and rapid, are described for the assay of
lamivudine in bulk drug and in tablet dosage forms using potassium iodate and two dyes, methyl orange and indigocarmine, as
reagents. In titrimetry, an aqueous solution of lamivudine is titrated directly with iodate in an acidic medium, and in the
presence of an excess of bromide using methyl orange as an indicator. After the decoloration of the red color of methyl orange,
the residual bromine is titrated iodometrically to a starch endpoint. Spectrophotometric methods involve the addition of a
known excess of iodate in an acidic medium and in the presence of an excess of bromide followed by the determination of residual
bromine by the reaction with a fixed amount of either methyl orange and measuring the absorbance at 520 nm (method A), or
indigo carmine and measuring the absorbance at 610 nm (method B). In all methods, the amount of iodate which reacted corresponds
to the amount of lamivudine content. The titrimetric method is applicable over the 1.5–8.0 mg range. The systems obey Beer’s
law for 0.5–5.0 μg/mL (method A) and 1.25–12.5 μg/mL (method B). The calculated apparent molar absorptivity values are found
to be 3.3 × 104 and 9.3 × 103 L mol−1 cm−1, for method A and method B, respectively, and the corresponding Sandell sensitivity values are 6.94 and 24.62 ng/cm2. The limits of detection and quantification are also reported for both spectrophotometric methods. Intra-and interday precision
and accuracy for the developed methods have been evaluated. The methods were successfully applied to the assay of lamivudine
in tablet form and the results were compared with those of a reference method by applying the Student’s t-test and F-test.
No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained
by recovery experiments using the standard addition technique.
The text was submitted by the authors in English. 相似文献
10.
MOHAMMAD-HUSSEIN Sorouraddin MOHAMMAD-REZA Rashidi BEHROOZ Shabani EBRAHIM Ghorbani-Kalhor 《中国化学》2005,23(2):160-165
A new synthesized fluorogenic reagent,8-[(2-pyridine)methylideneamino] quinoline
(PMAQ), was utilized for spectrofluorimetric determination of Cu(II) at trace levels. PMAQ, a good fluorogenic reagent, though insoluble in water, but is soluble in ethanol and 20% ethanol-water. The excitation and the fluorescence wavelengths of PMAQ were 310 and 434 nm respectively. When the reagent was complexed with Cu(II), the fluorescence intensity decreased proportionally with the concentration of Cu(II) at pH 4.5 by a static quenching effect. The highest sensitivity to Cu2+ determination was shown to be at PMAQ
concentration of 1.0×10-5mol•L-1. In order to enhance the quenching effect, the Cu(II)-PMAQ complex solution was kept at 22 ℃ for 20 min. Though the interferences by Co(II) and Fe(III) were very serious, they were however, completely eliminated by being masked with oxalate and ascorbate ions respectively. The linear dynamic range for Cu(II) determination was between 25—441 µg•L-1 with the detection limit of 18 µg•L-1 (RSD=3.7%, n=6). The proposed method was successfully applied to the determination of Cu(II) in real samples including
human blood serum, commercial tea and wheat flour. 相似文献
11.
Erkki Kolehmainen 《Russian Chemical Bulletin》1994,43(4):563-565
Results of multinuclear NMR studies of some heteroorganic compounds have been presented.According to a report at the conference «Current problems of organometallic chemistry» (May 8–13,1994, Moscow).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 614–616, April, 1994. 相似文献
12.
R. Plasil I. Korolov T. Kotrik J. Glosik 《International journal of mass spectrometry》2008,275(1-3):80-85
Recombination rate coefficients of protonated and deuterated ions KrH+, KrD+, XeH+ and XeD+ were measured using Flowing Afterglow with Langmuir Probe (FALP). Helium at 1600 Pa and at temperature 250 K was used as a buffer gas in the experiments. Kr, Xe, H2 and D2 were introduced to a flow tube to form the desired ions. Because of small differences in proton affinities of Kr, D2 and H2 mixtures of ions, KrD+/D3+ and KrH+/H3+ are formed in the afterglow plasma, influencing the plasma decay. To obtain a recombination rate coefficient for a particular ion, the dependencies on partial pressures of gases used in the ion formation were measured. The obtained rate coefficients, αKrD+(250 K) = (0.9 ± 0.3) × 10−8 cm3 s−1 and αXeD+(250 K) = (8 ± 2) × 10−8 cm3 s−1 are compared with αKrH+(250 K) = (2.0 ± 0.6) × 10−8 cm3 s−1 and αXeH+(250 K) = (8 ± 2) × 10−8 cm3 s−1. 相似文献
13.
Maria Assunta Meli Donatella Desideri Carla Roselli Laura Feduzi 《Microchemical Journal》2011,99(2):273-277
This paper describes the methods of sampling, preconcentration, chemical separation and final count of 210Po and 210Pb present in different marine matrices to determine their background levels in a marine ecosystem. Complex, time consuming and selective radioanalytical methods have been used to prepare final clear sources for alpha spectrometry and beta count; in fact, gamma spectrometry, a method direct and non destructive, cannot be taken into account because the 210Pb activity is very low which does not allow to carry out sufficiently accurate measurements and 210Po is not a gamma emitter but it emits only alpha particle at 5.40 MeV. The results of 210Po and 210Pb activity concentrations obtained in different marine samples collected in the first two campaigns are still very few to discuss about the 210Po and 210Pb behavior in marine environment. 相似文献
14.
Due to the importance of water in human life, its quality must be strictly controlled; for this purpose, simple and reliable analytical methods must be available. In this study, a monitoring of radioactivity content was performed in tap waters collected in a region of Central Italy to check the compliance with recent European and Italian regulations. Gross alpha and beta activities, 238U, 234U, 226Ra, 222Rn, and 3H concentrations were measured. Gross alpha and beta activities were determined by standard ISO 9696 and ISO 9697; for 226Ra, 222Rn and 3H determination, liquid scintillation was used. 238U and 234U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. The results revealed that the tritium concentration was always lower than 6.75 Bq l− 1. The concentrations (mBq l− 1) of 226Ra, 222Rn, 238U, and 234U ranged from < 1.70 to 15.31, from 0.69 to 20.3, from 0.65 to 48.77, and from 0.78 to 51.50, respectively.234U/238U ratios were higher than 1 in most cases. The results obtained revealed that, in most samples, gross alpha and gross beta were lower than the parameter value indicated in the international regulations. An attempt was also made to find a correlation between these results and the chemical parameters of waters. 相似文献
15.
Nuclear magnetic relaxation by intra- and intermolecular quadrupoleelectric field gradient interaction has been used for the study of the systems DMA-water-NaI and DMA-water-CsI at 25°C.14N relaxation of DMA and2H relaxation of D2O measured over the complete mixture range reveal the behavior of the rotational molecular motion of the two solvent components. For both solvent components a marked maximum of the reorientational correlation time has been found, reflecting hydrophobic effects and strong DMA-water interaction. The quadrupolar relaxation rates of23Na+ and133Cs+ in pure DMA were evaluated giving an indication that the electric solvent dipoles in the solvation shell are not located on positions of cubic symmetry. A quantitative study of preferential solvation of the cations in the mixed solvent has been performed by using the H2O-D2O isotope effect on23Na+ and133Cs+ relaxation. For both cations an obviously typical change in the selectivity occurs. In the range l>x
H2
O>0.7 we find weak preferential hydration, but in the range 0.7>xH
2
O>0 strong preferential solvation by DMA is reflected. 相似文献
16.
Liu Yuyan Liu Hongping Guo Yuanqing Liu Xiaoyong Lin Jieli Huang Guangming Gao Hui Li Jinrui 《中国科学B辑(英文版)》2000,43(2):121-128
LMR spectra for v=1←0 transitions of14N16O in X2II1/2, 3/2 states were observed at 5.6 μm and 5.4 μm of CO laser. Introducing the advanced isotopic molecular constant scaling function
to Hund’s case (a) diatomic structure model, these spectra were analyzed and fitted together with all reliable previous spectral
data of14N16O as well as14N17O and14N18O. A full set of precise molecular parameters and their vibrational dependencies have been determined with much higher precision
(1–2 orders for most parameters). Many of them have been obtained for the first time. Using isotopic scaling function, the
molecular constants of14N17O and14N18O were deduced. 相似文献
17.
A complex mixture of fluoro-polyphosphates (FPPs) and polyphosphates was prepared by heating a mixture of NaF and sodium tripolyphosphate (STPP) at 600 °C in nitrogen atmosphere. Two-dimensional 31P-19F heteronuclear correlation spectroscopy (HETCOR) NMR was developed in identifying the atomic connection between F and P in the mixed FPPs. 19F, 31P and 31P-31P correlation spectroscopy (COSY) NMR methods were employed to identify the components of the mixture and measure the chain length of each FPP ingredient. NMR results clearly demonstrated that the mixture contains four kinds of fluoro-phosphates with different chain length of polyphosphate, which are monofluoro-phosphate (MFP), monofluoro-dipolyphosphate (MFDPP), monofluoro-tripolyphosphate (MFTPP) and difluoro-tripolyphosphate (DFTPP). Other phosphates and polyphosphates also were found in the mixture. 相似文献
18.
Michal Maloň 《Tetrahedron letters》2007,48(43):7586-7590
Two-dimensional triple-resonance H(Si)C NMR experiments have been applied at natural abundance to assign 13C NMR signals in silylated phenols. The method showing its great potential in determining positions of hydroxyl groups is widely applicable to signal assignment and structure elucidation of synthetic and natural phenolic compounds. 相似文献
19.
Data on the NMR spectroscopy of C, N, O, Si, P, and Sn donor atoms of platinum metal complexes in solutions are surveyed. The chemical shift of a donor atom mainly depends on the ligand in the trans-position (due to the trans-effect). The chemical shift of a donor atom on a particular coordinate of the complex (coordinate shift, CSh) is an attribute of this coordinate and can be used to identify such a coordinate in platinum metal complexes and to determine the structures of complexes. Based on the known data, CSh diagrams were composed for 1H, 13C, 14N, 17O, 19F, 31P, and 119Sn. Examples of using the CShs for determining the structures of platinum metal complexes in solutions are presented. 相似文献
20.
Viktor Jobbágy Norbert Kávási János Somlai Borbála Máté Tibor Kovács 《Microchemical Journal》2010,94(2):159-165
Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.226Ra, 224Ra, 234U, 238U and 210Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L− 1) of 226Ra, 224Ra, 234U, 238U and 210Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y− 1 with an average 18.2 μSv y− 1 .This is well below the 100 μSv y− 1 reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y− 1, mainly due to the contribution from radium (226Ra, 224Ra) and 210Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake. 相似文献