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1.
In the present paper, an off-line preconcentration procedure for the determination of cadmium and lead by flame atomic absorption
spectrometry (FAAS) is proposed. Polyurethane foam (PUF) functionalized with o-aminophenol (o-AP) followed by Pyrazolone (Pyr)
packed in a minicolumn was used as a sorbent material. The metals were retained on the modified PUF, from which it could be
eluted and effectively preconcentrated. The detection limits were 0.072 and 0.016 μg L−1 for Pb and Cd respectively. Enrichment factors were 250 and 319 for lead and cadmium respectively. The procedure has been
applied successfully to metal determination in water samples, fish liver and reference material.
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2.
Ardeshir Shokrollahi Mojtaba Shamsipur Fahimeh Jalali Hamid Nomani 《Central European Journal of Chemistry》2009,7(4):938-944
A simple, sensitive and selective flotation method is described for the preconcentration and atomic absorption spectrometric
determination of zinc ion in water and blood samples. At a solution pH of 5.2, 4-(2-pyridylazo-resorcinol) and Triton X-114
were used as hydrophobic ligand and non-ionic surfactant, respectively. The chemical variables affecting the preconcentration
process were optimized. Under the optimized experimental conditions, the selective preconcentration and determination of as
low zinc concentration as 6.5 μg L−1 can be made. The proposed method was successfully applied to the preconcentration and low-level determination of zinc in
different water and blood serum samples.
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3.
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.
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4.
The potential of modified multiwalled carbon nanotubes (a solid-phase extraction sorbent), for the simultaneous separation
and preconcentration of lead, cadmium and nickel; has been investigated. Lead, cadmium and nickel, were adsorbed quantitatively;
on modified multiwalled carbon nanotubes (in the pH range of 2–4). Parameters influencing, the simultaneous preconcentration
of Pb(II), Ni(II) and Cd(II) ions (such as pH of the sample, sample and eluent flow rate, type and volume of elution solution
and interfering ions), have been examined and optimized. Under the optimum experimental conditions, the detection limits of
this method. for Pb(II), Ni(II) and Cd(II) ions, were 0.32, 0.17 and 0.04 ng mL−1 in original solution, respectively. Seven replicate determinations, of a mixture of 2.0 μg mL−1 lead and nickel, and 1.0 μg mL−1 cadmium; gave a mean absorbance of 0.074, 0.151 and 0.310, with relative standard deviation 1.7%, 1.5% and 1.2%, respectively.
The method has been applied, to the determination of trace amounts of lead, cadmium and nickel; in biological and water samples,
with satisfactory results.
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5.
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.
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6.
Petar T. Todorov Rosica N. Petrova Emilia D. Naydenova Boris L. Shivachev 《Central European Journal of Chemistry》2009,7(1):14-19
The crystal structures of 3-amino-cycloheptanespiro-4′-imidazolidine-2′,5′-dione (I) {systematic name: 3-amino-1,3-diazaspiro[4.6]
undecane-2,4-dione} and 3-amino-cyclooctanespiro-4′-imidazolidine-2′,5′-dione (II) {systematic name: 3-amino-1,3-diazaspiro[4.7]
dodecane-2,4-dione}, have been determined. In both compounds the polar hydantoin groups cause molecules to aggregate via N-H...O
and N-H...N interactions, forming a layer structure, in which the cycloalkane rings project outwards from the central, more
polar, region. The observed molecular structure is compared with that calculated by density functional theory methods.
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7.
Unusual reaction of 3,4-bis(3-nitrofurazan-4-yl)furoxan with ammonia,primary amines and hydrazine 总被引:1,自引:0,他引:1
Alexander A. Astrat’ev Dmitry V. Dashko Andrei I. Stepanov 《Central European Journal of Chemistry》2012,10(4):1087-1094
The nucleophilic displacement of two nitro groups in 3,4-bis(3-nitrofurazan-4-yl)furoxan with ammonia, primary aliphatic amines
and hydrazine leads to formation of a novel heterocyclic system, 7H-tris[1,2,5]oxadiazolo[3,4-b:3′,4′-d:3″,4″-f]azepine. The
reaction of compound 1 with secondary aliphatic amines proceeds in a typical way for nitrofurazans when the nitro-group in
the starting compound is substituted by RR’N-group.
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8.
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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9.
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.
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10.
Zholt Kormosh Iryna Hunka Yaroslav Bazel Andriy Laganovsky Iryna Mazurenko Nataliya Kormosh 《Central European Journal of Chemistry》2007,5(3):813-823
The potentiometric response characteristics of a diclofenac selective electrode, based on ion association in different plasticizers,
were compared. The sensitivity, working range, detection limit and selectivity of membrane sensors demonstrated significant
dependence on the type of plasticizers. The potentiometric unit presented a linear response toward diclofenac concentrations
between 1 × 10−5 − 5 × 10−2 mol L−1, with slopes of approximately 60 mV dec−1, and exhibited a response time of 3 s. The potentiometric analysis of sodium diclofenac in pharmaceutical formulations was
perfomed by the membrane electrode proposed and compared with the results of potentiometric titration given by the Pharmacopoeia
of Ukraine.
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11.
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
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.
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13.
Mehdi Ghandi Parham Asgari Abuzar Taheri Alireza Abbasi 《Central European Journal of Chemistry》2010,8(4):899-905
One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides is reported.
N-alkyl-2-(2-hydroxyphenyl)-2-iminoacetamide derivatives are generated presumably via the preliminary formation of N, N′-disubstituted benzo[b]furan-2,3-diamines and subsequent oxidation with molecular oxygen.
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14.
Titania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of
a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor
were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 μM with detection
limit 12 μM and a high sensitivity 12.5 nA μM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation
of ethanol catalyzed by alcohol dehydrogenase (ADH).
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15.
Joanna Kurczewska Radosław Pankiewicz Grzegorz Schroeder 《Central European Journal of Chemistry》2012,10(5):1452-1458
Silica surface was modified with quaternary ammonium salts to give three matrices of different chain length. The synthesized supports were characterized by elemental analysis and infrared spectroscopy, as well as scanning electron microscopy and semi-empirical parametric method 5. Their exchange capacities for ClO4 −, F−, NO3 − and CH3COO− ions were investigated by conductometric titration. The amount of exchanged chloride ions from the matrix was studied for different initial anions concentration. The functionalized silica gel showed very good ability of perchlorate ions exchange from the water solution in room temperature. The anion-exchange properties were also studied in comparison to different number of reactive sites in the matrices. The increased number of chloride at the silica surface took effect on increased ability of ClO4 − anion exchange 相似文献
16.
Aleksandra Prichodko Kristina Jonusaite Vida Vickackaite 《Central European Journal of Chemistry》2009,7(3):285-290
A hollow fibre liquid phase microextraction for gas chromatographic determination of some p-hydroxybenzoic acid esters has
been developed. Chlorobenzene containing tetradecane as internal standard was used for the extraction. Optimized extraction
was carried out at room temperature for 40 min in the presence of 0.4 g mL−1 NaCl in the sample solution. Calibration was linear up to 30 mg L−1. Correlation coefficients were 0.996–0.998. Enrichment factors were 21, 95 and 154, and detection limits were 0.20, 0.03
and 0.01 μg mL−1 for methylparaben, ethylparaben and propylparaben, respectively. Reproducibility was acceptable with relative standard deviations
up to 11.7%. The technique was tested for water and urine analysis.
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17.
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.
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18.
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.
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19.
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.
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20.
Jorge Luis Sague Doimeadios 《Central European Journal of Chemistry》2008,6(4):505-508
Herein, the first example of a co-crystal system formed by an imidazolium nitrate, a carbene precursor, and copper (II) nitrate,
{[Cu(NO3)2(H2O)2]L1(NO3)2} (1) (L1 = 1,1′-dibenzyl-3,3′-butyl-diimidazolium-2,2′-diylidene) is reported. These two building blocks are connected in the solid
state through hydrogen bonds to generate a three-dimensional supramolecular network.
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