共查询到20条相似文献,搜索用时 31 毫秒
1.
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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2.
Sequential extraction and thermal desorption of mercury from contaminated soil and tailings from Mongolia 总被引:1,自引:0,他引:1
Pavel Coufalík Pavel Krásenský Marek Dosbaba Josef Komárek 《Central European Journal of Chemistry》2012,10(5):1565-1573
Mercury forms in contaminated environmental samples were studied by means of sequential extraction and thermal desorption from the solid phase. The sequential extraction procedure involved the following fractions: water soluble mercury, mercury extracted in acidic conditions, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS, and residual mercury. In addition to sequential extraction, the distribution of mercury species as a function of soil particles size was studied. The thermal desorption method is based on the thermal decomposition or desorption of Hg compounds at different temperatures. The following four species were observed: Hg0, HgCl2, HgS and Hg(II) bound to humic acids. The Hg release curves from artificial soils and real samples were obtained and their applicability to the speciation analysis was considered. 相似文献
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.
Tsonko Kolev Bojidarka B. Koleva Michael Spiteller 《Central European Journal of Chemistry》2008,6(3):393-399
The applications of linear-polarized IR-spectroscopy to oriented colloid suspensions in a nematic host are demonstrated with
croconic and rhodizonic acids. The experimental IR vibrational assignments of the solid-state of both neutral compounds are
presented. Assignments are supported by theoretical quantum chemical calculations and vibrational analysis at the DFT level
of theoretical approximation with the 6-311++G** basis set.
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5.
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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6.
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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7.
A novel hydroxyamino phosphane was synthesised through the reaction of 2-imidazolidinone with ClPPh2 and subsequently reaction
of the resulting bisphosphino derivative with the Grignard reagent BrMgC5H11. The interaction of the pentyl substituent with one of the two phosphino groups and the structure in solution is shown by
multinuclear NMR-spectroscopy..
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8.
Phase equilibria established in the PbO - BiVO4 system over the whole component concentration range up to 1000°C have been investigated. A phase diagram has been constructed
using DTA and XRD.
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9.
Eugenia D. Teodor Simona C. Liţescu Antonela Neacşu Georgiana Truică Camelia Albu 《Central European Journal of Chemistry》2009,7(3):560-568
The study aims to establish several definite criteria which will differentiate Romanian amber and Baltic amber to certify
the local or Baltic origin of the materials found in archaeological sites on the Romanian territory, by using light microscopy
and performing analytical methods, such as Fourier transform infrared spectroscopy-variable angle reflectance and liquid chromatography
with mass spectrometry detection. Experiments especially by Fourier transformed infrared spectroscopy, were applied to a wide
range of samples with controlled origin. The methods were optimised and resulted in premises to apply the techniques to analysis
of the archaeological material.
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10.
Khalid Hamad Abu-Shandi 《Central European Journal of Chemistry》2009,7(3):354-361
A quick method of quantitative determination of sulbactam in human plasma, using liquid chromatography-UV spectroscopy, has
been developed and validated. After derivatization with imidazole, plasma samples were treated by direct deproteinization
with acetonitrile as an extraction solvent. After ultracentrifugation, sulbactam extract was directly injected onto the LC
column. Chromatographic separation was performed on TSK Gel Super ODS (50 mm × 4.6 mm i.d., 2 μm) using methanol and phosphate buffer with tetrabutylammonium hydroxide solution as a mobile phase. Gradient elution
was employed. The method was fully validated according to the United States Food and Drug Administration requirements (linearity,
precision, trueness, quantification limit, detection limit, recovery, specificity and stability). The calibration curves were
linear within the concentration range of 0.05–4.0 μg mL−1. Good method/system precision and accuracy of the method were demonstrated.
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11.
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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12.
Santosh S. Katkar Pravinkumar H. Mohite Lakshman S. Gadekar Balasaheb R. Arbad Machhindra K. Lande 《Central European Journal of Chemistry》2010,8(2):320-325
A rapid and an efficient one-pot method for the synthesis of quinoxalines catalysed by ZnO-beta zeolite at room temperature
is described. This environmentally benign method provides several advantages over methods that are currently employed such
as a simple work-up, mild reaction conditions, good to excellent yields, and a process to recover and reuse the catalyst for
several cycles with consistent activity.
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13.
14.
Vivek Srivastava 《Central European Journal of Chemistry》2010,8(2):269-272
Sulphonimide based organocatalyst was used to catalyze the aldol reaction in ionic liquid media. On the basis of yield and
selectivity the ionic liquid mediated system was found superior in comparison with organic solvents. The added advantages
of this ionic liquid mediated organocatalysis are easy recovery of product and the recyclability of the organocatalyst.
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15.
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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16.
Joanna Kurczewska Grzegorz Schroeder Urszula Narkiewicz 《Central European Journal of Chemistry》2010,8(2):341-346
The synthesis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials coated with cyclam-bonded silica has been described.
The organic layer was identified by Fourier transform infrared spectroscopy and elemental analysis. The functionalized magnetic
nanomaterials were employed to extract the divalent cations: copper, calcium, cobalt, manganese and nickel from aqueous solutions.
Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by
inductively coupled plasma mass spectrometry. Influence of different parameters viz. pH, amount of the compound studied, contact
time, on the cation extraction was investigated. Under optimum conditions copper extraction was significantly more efficient
when compared with other coexisting ions.
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17.
José L. Tadeo Consuelo Sánchez-Brunete Beatriz Albero Ana I. García-Valcárcel Rosa A. Pérez 《Central European Journal of Chemistry》2012,10(3):480-520
Spreading sewage sludge on agricultural lands has been actively promoted by national authorities as an economic way of recycling.
However, as by-product of wastewater treatment, sewage sludge may contain toxic substances, which could be incorporated into
agricultural products or be distributed in the environment. Moreover, sediments can be contaminated by the discharge of wastewater
effluents into rivers. This article reviews the determination of emerging contaminants (surfactants, flame retardants, pharmaceuticals
and personal care products) in environmental solid samples (sludge, soil and sediment). Sample preparation, including extraction
and clean-up, as well as the subsequent instrumental determination of contaminants are discussed. Recent applications of extraction
techniques, such as Soxhlet extraction, ultrasound assisted extraction, pressurised liquid extraction, microwave assisted
extraction and matrix solid-phase dispersion to the analysis of emerging contaminants in environmental solid samples are reviewed.
Determination of these contaminants, generally carried out by gas chromatography and liquid chromatography coupled with different
detectors, especially mass spectrometry for the identification and quantification of residues, is also summarised and discussed.
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18.
Tuula Kylmälä Jan Tois Youjun Xu Robert Franzén 《Central European Journal of Chemistry》2009,7(4):818-826
Diflunisal and Felbinac, two FDA-approved NSAIDs and other biphenyl carboxylic acids were prepared in one step by a simple
and clean Suzuki cross-coupling reaction using an easily synthesized, air and moisture stable, palladium-diamine complex.
The yield (93%) for the one-step preparation of Diflunisal is the best reported without using a glovebox and a phoshine-based
catalyst.
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19.
Lakshman S. Gadekar Shivshankar R. Mane Santosh S. Katkar Balasaheb R. Arbad Machhindra K. Lande 《Central European Journal of Chemistry》2009,7(3):550-554
Natural scolecite has been found as an effective catalyst for the one-pot synthesis of 2,4,5-triarylimidazole derivatives
via a three component reaction using benzil or benzoin, aldehydes and ammonium acetate. This method provides several advantages
such as being environmentally benign, reusable, possessing high yields with increased variations of the substituents in the
product and preparative simplicity.
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20.
This article describes the simple hydrodehalogenation of halogenated anilines and their derivatives by the action of Raney
aluminium-nickel alloy in aqueous alkaline solution at room temperature. The reaction course was monitored by means of 1H
nuclear magnetic resonance (NMR) spectroscopy and GC-MS spectra.
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