共查询到20条相似文献,搜索用时 46 毫秒
1.
Lyudmila A. Belyakova Oleksandra M. Shvets Diana Yu. Lyashenko 《Central European Journal of Chemistry》2008,6(4):581-591
The present work investigates the adsorptive interactions of Hg(II) ions in aqueous medium with hydroxylated silica, aminopropylsilica
and silica chemically modified by β-cyclodextrin. Batch adsorption studies were carried out with various agitation times and
mercury(II) concentrations. The maximum adsorption was observed within 15–30 min of agitation. The kinetics of the interactions,
tested with the model of Lagergren for pseudo-first and pseudo-second order equations, showed better agreement with first
order kinetics (k1 = 3.4 ± 0.2 to 5.9 ± 0.3 min−1). The adsorption data gave good fits with Langmuir isotherms. The results have shown that β-cyclodextrin-containing adsorbent
has the largest adsorption specificity to Hg(II): K
L
= 4125 ± 205 mmol−1. “β-cyclodextrin-NO3-” inclusion complexes with ratio 1: 1 and super molecules with composition C42H70O35 ⊎ 3 Hg(NO3)2 are formed on the surface of β-cyclodextrin-containing silica.
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2.
Jinzhang Gao Yingying Zhang Jie Ren Ming Li Wu Yang 《Central European Journal of Chemistry》2010,8(3):602-606
A sensitive and convenient method for the determination of trace europium ions using an oscillating chemical reaction involving
Ce(IV) - KBrO3 - acetone - oxalic acid - H2SO4 was proposed. The results indicated that the changes in oscillating period (T) was linearly proportional to the negative
logarithmic concentration of Eu3+ (-log C) in the range of 1.41 × 10−8 ˜ 1.41 × 10−4 mol L−1 (r = 0.9982) with a detection limit of 1.04 × 10−9 mol L−1. The recoveries were limited to the range of 99.5% to 100.8%. Under the same conditions, other rare earth ions did not interfere
with the determination of Eu3+. In addition, a perturbation mechanism was also discussed briefly.
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3.
Charles A. Mebi Joshua J. Trujillo Anwar A. Bhuiyan 《Central European Journal of Chemistry》2012,10(4):1218-1222
A new organometallic complex coupling photoactive coumarin to a diironhexacarbonyl unit has been successfully prepared and its composition and electronic structure confirmed by elemental and spectroscopic analyses. Emission spectral analysis of the complex reveals photoinduced intramolecular electron transfer from coumarin to the iron-carbonyl moiety. The compound is electrochemically reduced at −1.24 V vs. Fc/Fc+. This reduction is irreversible, attesting to the instability of the complex. Electrochemical evolution of hydrogen in the presence of the complex has been studied and results are discussed. 相似文献
4.
Determination of Alizarin Red S using a novel B-Z oscillation system catalyzed by a tetraazamacrocyclic complex 总被引:1,自引:0,他引:1
Gang Hu Lulu Chen Jinfeng Zhang Panpan Chen Wei Wang Jimei Song Lingguang Qiu Juan Song Lin Hu 《Central European Journal of Chemistry》2009,7(3):291-297
A new and convenient method for the determination of Alizarin Red S by the perturbations caused by different amounts of Alizarin
Red S on a novel B-Z oscillating system is proposed. This new type Belousov-Zhabotinskii involves a macrocyclic copper(II)
complex [CuL](ClO4)2 as catalyst and malic acid as the substrate. The ligand L in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene.
It is found that the relationship between the change in the oscillation amplitude and the logarithm of the Alizarin Red S
concentration in the range of 1.5 × 10−7 to 1 × 10−3 M fits a polynomial model: ΔA = 659 + 184.2 log [Alizarin Red S]+ 12.9 log2 [Alizarin Red S]. The RSD obtained with ten samples is 4.4%. The probable mechanism involving the perturbation of Alizarin
Red S on the oscillating chemical system is also discussed.
相似文献
5.
Violeta D. Mitic Snezana D. Nikolic Vesna P. Stankov-Jovanovic 《Central European Journal of Chemistry》2010,8(3):559-565
A kinetic spectrophotometric method for hydrazine determination in the range of 9.36×10−7 to 4.37×10−5 mol dm−3, based on the inhibitory effect of hydrazine on the oxidation of Victoria Blue 4- R by KBrO3, was developed and validated. Kinetic parameters are reported for both the indicating and the inhibiting reaction. The detection
limit was established as 9.98×10−8 mol dm−3. The selectivity of the proposed method was tested considering the influence of different ions that may be present in real
samples. The method was successfully applied for hydrazine determination in various samples (very pure water from the water-steam
system of a power plant and Isoniazid tablets, a pharmaceutical product).
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6.
Mónica Díaz-Pérez Manuel Aboal-Somoza Pilar Bermejo-Barrera Adela Bermejo-Barrera 《Central European Journal of Chemistry》2008,6(4):520-525
Preliminary results of development of a direct and fast method of determination of antimony in samples of tap water using
GFAAS are presented. The found levels of antimony were lower than permitted for human consumption. A mixture of Pd and Mg(NO3)2 (concentrations in the injected solution: 8.6 μg mL−1 and 5.8 μg mL−1 respectively) was used as the chemical modifier. The pyrolysis and atomization temperatures were 1000 and 1700°C, respectively
and the mean analytical recovery 98.2%.
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7.
Joanna Lenik Cecylia Wardak Barbara Marczewska 《Central European Journal of Chemistry》2008,6(4):513-519
Naproxen membrane electrodes based on different plasticizers and the quaternary ammonium salts (QASs) dimethyldidecylammonium
bromide, methyltrioctylammonium chloride, or tetraoctylammonium chloride, were prepared. The following basic parameters were
investigated for the optimal electrode: measurement range (10−4 − 10−1 mol L−1), slope of the linear range of the calibration curve (−58.3 mV decade−1), limit of detection (6.0 × 10−5 mol L−1), lifetime (2.5 months), dependence of the electrode potential on pH (5.5 − 9.0), reproducibility of potential (1.2 mV) and
selectivity coefficients in relation to selected organic and inorganic anions. The electrode was utilized for determination
of naproxen in tablets by the calibration curve method and the standard addition method.
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8.
Nitin A. Mirgane Sandip B. Kotwal Anil V. Karnik 《Central European Journal of Chemistry》2010,8(2):356-360
Ionic liquids (IL) are gaining importance as green solvents. Imidazolium ionic liquid [bmim]+[Cl]−, an environmentally benign solvent, was found to promote the Diels-Alder reaction between anthrone and maleimides at room
temperature with excellent yields. The ionic liquid played a dual role as solvent and catalyst.
相似文献
9.
Dispersive liquid-liquid microextraction and liquid chromatographic determination of pentachlorophenol in water 总被引:1,自引:0,他引:1
Khalil Farhadi Mir A. Farajzadeh Amir A. Matin Paria Hashemi 《Central European Journal of Chemistry》2009,7(3):369-374
A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol
(PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V
sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent.
The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear
dynamic range (0.1–1000 μg L−1) and low detection limit (0.03 μg L−1), which makes it suitable for determination of PCP in water samples.
相似文献
10.
The triplet excited state properties and photosensitization mechanisms of indigo were investigated based on density functional
theory calculations. The solvent effects on the photosensitization mechanisms of indigo have also been considered. The thermodynamic
feasibility of the possible 1O2 and O2·−-photogeneration pathways by triplet excited state indigo in different solvents was explored, in order to gain some deeper
insights into the photosensitization characters of the dye.
相似文献
11.
Elisaveta K. Mladenova Ivanka G. Dakova Dimiter L. Tsalev Irina B. Karadjova 《Central European Journal of Chemistry》2012,10(4):1175-1182
A sorbent L-cysteine grafted silica gel has been evaluated for separation and enrichment of dissolved inorganic i-Hg(II) and methylmercury CH3Hg(I) from surface waters at sub-μg L−1 concentrations. Chemical parameters for mercury species enrichment and separation have been optimized. Analytical schemes for the determination of Hg species, using selective column solid phase extraction (SPE) with continuous flow chemical vapor generation atomic absorption spectrometry (CF-CVG-AAS) or inductively coupled plasma-mass spectrometry (ICP-MS) were developed. Possibilities for on-site SPE enrichment were demonstrated as well. The limits of quantification were 1.5 and 5 ng L−1 for dissolved i-Hg(II) and CH3Hg(I) by CF-CVG-AAS and 1 and 2.5 ng L−1 by ICP-MS with relative standard deviations between 7–12% and 7–14%, respectively. The chemically modified SPE sorbent has demonstrated high regeneration ability, chemical and mechanical stability, acceptable capacity and good enrichment factors. Results for total dissolved mercury were in reasonable agreement with those from independent analyses by direct ICP-MS determinations for river waters and for estuarine water certified reference material. 相似文献
12.
Ksenija R. Kumrić Tatjana M. Trtić-Petrović Ljubiša M. Ignjatović Jožef J. Čomor 《Central European Journal of Chemistry》2008,6(1):65-69
Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA.
Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically,
resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL−1 lutetium could be detected after a 2 min deposition.
相似文献
13.
Cecylia Wardak 《Central European Journal of Chemistry》2008,6(4):607-612
A new all plastic sensor for Co2+ ions based on 2-amino-5 (hydroxynaphtyloazo-1′)-1,3,4 thiadiazole (ATIDAN) as ionophore was prepared. The electrode exhibits
a low detection limit of 1.5 × 10−6 mol L−1 and almost theoretical Nernstian slope in the activity range 4.0 × 10−6–1 × 10−1 mol L−1 of cobalt ions. The response time of the sensor is less than 10 s and it can be used over a period of 6 months without any
measurable divergence in potential. The proposed sensor shows a fairly good selectivity for Co(II) over other metal ions.
The electrode was successfully applied for determination of Co2+ in real samples and as an indicator electrode in potentiometric titration of Co2+ ions with EDTA.
相似文献
14.
Saravanakumar Shanmuganathan Olaf Kühl Peter G. Jones Joachim Heinicke 《Central European Journal of Chemistry》2010,8(5):992-998
The reaction of chloroethyltrimethylsilylether with 1-methylimidazole furnishes an ionic liquid that undergoes methanolysis
to crystalline 2-hydroxyethylimidazolium chloride (crystal structure presented). Conversion to defined hydroxyethylimidazol-2-ylidene
nickel complexes failed, but was accomplished with 1-methyl-3-acetophenyl-imidazolium bromide. The bis(NHC⋂O−) nickel(II) chelate is formed, rather than a methallylnickel monochelate, but with nickelocene a monochelate NiCp complex
was detected. The bulky 1-(2,6-diisopropylphenyl)-3-(2’-phenyl-enolato)-imidazol-2-ylidene allylpalladium chloride was obtained
in pure form. Attempts to generate catalysts for ethylene oligomerization by in situ techniques have failed so far whereas P⋂O− ligands, comparable by the P-C diagonal relationship, provide active catalysts.
相似文献
15.
Dmitriy A. Golovko Virender K. Sharma Olga. V. Pavlova Elena. A. Belyanovskaya Igor. D. Golovko Victoria. I. Suprunovich Radek Zboril 《Central European Journal of Chemistry》2011,9(5):808-812
A new amperometric titration method was developed for quantitative determination of ferrate(VI) (FeVIO4
2−) in the 7.06×10−5−5.73×10−3 M concentration range. Chromium(III) hydroxide solution was used as the titrant. The diffusion current (Id) had a linear
relationship with the concentration of ferrate(VI) and slopes were dependent on the concentration of NaOH. The amperometric
titration could detect a lower concentration of ferrate(VI) than could potentiometric and colorimetric titrations. The method
was applied successfully to determine concentrations of ferrate(VI), generated electrochemically, in strong alkaline solutions.
相似文献
16.
Nikolai N. Kolesnikov Elena B. Borisenko Dmitrii N. Borisenko Boris A. Gnesin 《Central European Journal of Chemistry》2011,9(4):619-623
In the present study newly produced semiconductor ceramic nanopowder materials made of CdTe and Cd1−xZnxTe (CZT) are considered. Common features and differences in microstructures, phase transformations, grain growth and properties
of the ceramic materials of the binary and ternary compositions are studied.
相似文献
17.
Yuxi Ren Zhen Chen Riyao Chen Xi Zheng Yamin Geng 《Central European Journal of Chemistry》2007,5(1):177-190
The preparation of SAMS-CMC-CS bipolar membrane grafted onto CMC by SAMS was reported. The cross-section view of SAMS-CMC-CS
BM were studied by SEM. FT-IR spectrum indicated that SAMS-CMC-CS BM contained-SO
3
−
,-COO− and −N=CHR functional groups. Compared with CMC-CS BM, SAMS-CMC-CS BM appears to have better mechanical strength and chemical
stability in alkali solution at [OH−]≥9.5 mol/L, with a swelling of 55 %. The electrochemical properties of SAMS-CMC-CS BM were also studied. SAMS-CS-CMC BM not
only effectively prevented FeO
4
2−
from diffusing into the cathode chamber, but also played an important role in the supply of OH− consumed during the electro-generated FeO
4
2−
process.
相似文献
18.
Alexandru Cecal Doina Humelnicu Valeriu Rudic Liliana Cepoi Angela Cojocari 《Central European Journal of Chemistry》2012,10(5):1669-1675
This paper deals with a study of the biosorption of UO2 2+ ions on two green algae: Chlorella vulgaris and Dunaliella salina. By investigating the retention degree versus contact time from Langmuir and Freundlich biosorption isotherms, kinetic investigations and FTIR spectra it was found that the biosorption process was greater for Chlorella vulgaris than for Dunaliella salina. A new kinetics method is proposed to establish the reaction order concerning the biosorption process of uranyl ions on these biomasses. 相似文献
19.
Hana Dejmkova Candan Dag Jiri Barek Jiri Zima 《Central European Journal of Chemistry》2012,10(4):1310-1317
New methods for the determination of metoclopramide, antiemetic and gastroprokinetic pharmaceutical, were developed, using
differential pulse voltammetry (DPV) and flow injection analysis (FIA) with amperometric detection on a boron-doped diamond
film electrode. Electrode pretreatment necessary to ensure the stable results was investigated and it was found, that while
DPV requires frequent electrode cleaning, FIA with a sufficiently high flow rate can maintain a stable signal with no signs
of electrode passivation. The calculated quantification limits of the DPV and FIA with amperometric detection were 0.13 μmol
L−1 and 0.015 mmol L−1, respectively. The applicability of the new methods was verified by the determination of metoclopramide in a pharmaceutical
preparation. FIA with amperometic detection proved to be sensitive, accurate and, due to the resistance of the electrode to
the passivation, also simple to handle.
相似文献
20.
Aleksandra Dubiella-Jackowska Żaneta Polkowska Lech Dariusz Piotr Pasławski Wojciech Staszek Jacek Namieśnik 《Central European Journal of Chemistry》2009,7(1):35-41
A solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass
spectromA solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma
mass spectrometry (ICP-MS) was developed. The method was based on retention of platinum in a sample on silica gel modified
with aminepropyl groups. The retention of platinum(IV) from the sample solution and the recovery of platinum with 1.0 mol
L−1 thiourea solution were quantitative. The relative standard deviation (RSD) was calculated as 5% (n = 7) at the 10 ng L−1 level. The enrichment factor was found to be (50-fold) for 250 mL of water sample. Under optimum conditions, the method detection
limit (MDL) was found to be 1 ng L−1 for platinum in water matrices. Recoveries of Pt from spike addition to atmospheric water samples were quantitative (80–95%).
The present method was used for the determination of platinum in precipitation, throughfall and runoff water samples.
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