共查询到20条相似文献,搜索用时 31 毫秒
1.
Electrochemical determination of dopamine (DA) in the presence of ascorbic acid (AA) was achieved on boron-doped diamond (BDD)
film electrode by differential pulse voltammetry. The experimental results indicated that the oxidative peaks of DA and AA
could be separated completely on anodically-treated (BDD) electrode without further modification, although these two peaks
can not be separated on glassy carbon electrode. The peak separation of DA and AA was developed to be 0.44 V. High sensitivity
was obtained to determine DA selectively with the coexisting of a large excess of AA in acidic media by DPV. The detection
limit of DA was achieved to be 1.1 × 10-6 M in the presence of AA with the concentration of 200 times more than DA. This technique was also applied to the determination
of DA in real samples.
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2.
Rūta Araminaitė Rasa Garjonytė Albertas Malinauskas 《Central European Journal of Chemistry》2009,7(4):739-744
Electrooxidation of ascorbate has been studied with the use of a rotating disk electrode. The results obtained show an efficient
electrocatalytic oxidation of ascorbate at the Prussian blue (PB) modified electrode to proceed in solutions of pH 5.5 and
7.3. Depending on solution pH, the onset potential for ascorbate electrooxidation at PB modified electrode appears shifted
by 0.1–0.2 V to lower values, as compared to an unmodified glassy carbon electrode. Within the electrode potential window
of 0.3 to 0.5 V vs. Ag/AgCl, and electrode rotation velocity of 50–2000 rpm, the catalytic current obeys Koutecky-Levich equation at a submillimolar
ascorbate concentration. Kinetic current densities, obtained from the data treatment, are higher for a pH 5.5 solution, and
also at higher electrode potential.
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3.
Mir Reza Majidi Reza Fadakar Bajeh Baj Abdolhossein Naseri 《Central European Journal of Chemistry》2013,11(7):1172-1186
Room temperature 1-butyl-3-methylimidazolium tetraflouroborate ([BMIM][BF4]) ionic liquid was employed for dispersion of multi walled carbon nanotubes (MWCNTs) and the formation of nanocomposite on the surface of a carbon-ceramic electrode. The surface of the modified electrode was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The modified electrode exhibited excellent electrochemical activity to oxidation of dopamine (DA); whereas electro oxidation of ascorbic acid (AA) was not seen and electro oxidation of uric acid (UA) appeared at a more positive potential than DA. The multi walled carbon nanotube-ionic liquid nanocomposite modified carbon-ceramic electrode was used for the selective determination of DA in the presence of high levels of AA and UA using differential pulse voltammetry. The calibration curve for DA was linear in the range of 3.00 to 130 µM with the detection limit (S/N=3) of 0.87 µM. The present electrode was successfully applied to the determination of DA in some commercial pharmaceutical samples and human blood serum. 相似文献
4.
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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5.
Anuţa Câmpean Mihaela Tertiş Robert Săndulescu 《Central European Journal of Chemistry》2011,9(4):688-700
Electrochemical behaviour of some alkaloids, namely: caffeine, aminophylline, theophylline, codeine phosphate and papaverine
hydrochloride, that are in solution in various combinations or in the presence of other compounds contained in pharmaceuticals
or in real samples (urine) was investigated using cyclic voltammetry (CV), square-wave voltammetry (SWV) and differential
pulse voltammetry (DPV) on electrochemically activated glassy carbon electrode.
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6.
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
7.
The oxidation processes of 2,6-diisopropylnaphthalene and 4,4′-diisopropylbiphenyl with oxygen in the presence of a catalyst,
composed of copper(II) chloride and tetrabutylammonium bromide, were investigated. It was found that, in essence, only one
isopropyl group undergoes oxidation, and obtained mixtures contained mainly peroxide, alcohol, ketone and only small amounts
of hydroperoxide.
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8.
Sylwia Smarzewska Sławomira Skrzypek Barbara Bachowska Piotr Bałczewski Witold Ciesielski 《Central European Journal of Chemistry》2011,9(5):840-845
Electrochemical oxidation of methylthiomethyleneisoquinolinium chloride (MTMIQ), the first alkylthiomethyl substituted ammonium
salt, which is fully miscible with water has been investigated by voltammetric (SWV) method using glassy carbon electrode.
On the electrode, MTMIQ undergoes oxidation at the potential near Ep = 0.07V (vs. Ag/AgCl/3 M KCl). The influence of the pH
of buffers, amplitude, frequency, step potential on the received signal was studied. The best results were obtained with a
citrate buffer at a pH of 5. The oxidation peak current used for MTMIQ voltammetric determination was in the range of 2–8×10−5 mol L−1, LOD = 3.7×10−6, LOQ = 1.2×10−5. The product of the oxidation was accumulated at the working electrode and was investigated by spectroscopic method. Mechanistic
pathways of the oxidation have been proposed.
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9.
Aline de Oliveira-Roberth Diego I. V. Santos Diogo D. Cordeiro Fernando M. de A. Lino Maria T. F. Bara Eric de S. Gil 《Central European Journal of Chemistry》2012,10(5):1609-1616
Rutin is a flavonoid commonly employed for many therapeutic purposes. Although the electroactive phenolic groups of rutin might be oxidized at low applied potential, the adsorption of oxidized species changes the electrode surface. As a consequence, the repeatability and reproducibility of the method decreases, which limits electroanalytical applications. This paper describes the use of disposable screen-printed electrodes as an alternative to improve the electrochemical quantification of rutin in commercial and standard samples. The electrochemical behavior was consistent to what is observed using other carbon electrodes: an adsorption-involved step and a pH-dependent oxidation process. The replacement of the electrodes between the analyses ensured rapid analysis, good intermediate precision and repeatability. The proposed method was successfully applied to rutin determination in pharmaceutical samples of capsules, with the limit of quantification being 0.30 μM. 相似文献
10.
Carbon paste electrodes in the new millennium 总被引:1,自引:0,他引:1
Ivan Švancara Alain Walcarius Kurt Kalcher Karel Vytřas 《Central European Journal of Chemistry》2009,7(4):598-656
In this review (with 500 refs), both electrochemistry and electroanalysis with carbon paste-based electrodes, sensors, and
detectors are of interest, when attention is focused on the research activities in the years of new millennium. Concerned
are all important aspects of the field, from fundamental investigations with carbon paste as the electrode material, via laboratory
examination of the first electrode prototypes, basic and advanced studies of various electrode processes and other phenomena,
up to practical applications to the determination of inorganic ions, complexes, and molecules. The latter is presented in
a series of extensive tables, offering a nearly complete survey of methods published within the period of 2001–2008. Finally,
the latest trends and outstanding achievements are also outlined and future prospects given.
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11.
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.
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12.
13.
A cathodic differential pulse voltammetric determination of colchicine was validated using a glassy carbon electrode in HClO4/H3PO4 0.01 M. Colchicine gives an irreversible, diffusion-controlled peak at −862 mV vs. Ag/AgCl reference electrode. The cathodic
peak is strongly influenced by a more alkaline environment with a shift towards more negative potentials. Method optimization
was carried out in parallel for three types of electrodes (glassy carbon, mercury film and bismuth film coated glassy carbon).
The cathodic peak current is higher using film-coated electrodes, but shows poorer intra-day reproducibility and a longer
analysis time due to film renewal. Thus, a bare glassy carbon electrode was used to determine colchicine in the concentration
range of 2.4 − 50 μg mL−1 (R
2 = 0.9998, n = 5), with a calculated detection limit of 0.80 μg mL−1. The proposed method was characterized according to ICH Harmonized Tripartite Guidance Q2(R1) by validation parameters (selectivity,
linearity, accuracy, fidelity, limit of detection, limit of quantification) and it was successfully applied for the determination
of colchicine from tablets, without the interference of the excipients. The method’s performances were evaluated and compared
with both a known polarographic method and the official quantitative spectrophotometric determination from the Romanian Pharmacopoeia,
Xth edition, respectively.
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14.
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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15.
Martin Adam Petr Dobiáš Petra Pavlíková Karel Ventura 《Central European Journal of Chemistry》2009,7(3):303-311
The analytical microextraction methods of gas chromatography coupled with flame ionisation detector (GC-FID) for determination
of selected essential oils in herbs were proposed. Two microextraction methods for the isolation of essential oils from plants
such as Lavandula spica L., Melissa officinalis L., Mentha piperita L. and Salvia officinalis L. were used. The methods of solid-phase and single-drop microextractions, were optimised and compared. The obtained LOD
values for all studied essential oils were found to be within 2.5–20.5 μg for SDME and 57.0–139.8 μg for SPME method per 100
g of dried sample leaves. The appropriate LOQ values were then 8.4–68.4 μg for SDME and 189.8–466.1 μg for SPME of target
analytes per 100 g of dried sample leaves.
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16.
Oztekin Algul Asiye Meric Serpil Polat N. Didem Yuksek Mehmet S. Serin 《Central European Journal of Chemistry》2009,7(3):337-342
Comparative studies were performed on a series of 2,4-di and 2,3,4-trisubstituted benzimidazo[1,2-a]pyrimidines, which were
synthesized with conventional and microwave heating methods. In microwave irradiation method, approximately, 95–97.5% of the
reaction time was increased and 1–45% yield increase was obtained. All compounds were able to inhibit the growth of the screened
microorganisms in vitro with MIC values between 3.9–250 μg mL−1. The highest activity was expressed by compound IIId (2,4-diphenyl-benzo[4,5]imidazo[1,2-a] pyrimidine), which has the MIC
value of 3.9 μg mL−1 and 31.2 μg mL-1 for Penicillium natatum ATCC 24791 and E. faecalis ATCC 29212, respectively.
相似文献
17.
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
18.
Grzegorz Lota Krzysztof Fic Krzysztof Jurewicz Elzbieta Frackowiak 《Central European Journal of Chemistry》2011,9(1):20-24
Electrochemical storage of hydrogen in activated carbon material has been investigated using different parameters of cathodic
polarization. It has been proven that application of short galvanostatic pulses could be efficient for hydrogen storage in
microporous carbon material. Charging current loads from 50 mA g−1 to 32 A g−1 have been used showing correlation between hydrogen capacity, time of charging and electrical efficiency. The anodic charge
equivalent to electrooxidation of 1.0 wt% of hydrogen can be already reached after 90 s of cathodic polarization. Temperature
effect has been also evaluated and a gradual increase of hydrogen capacity with a better pronounced oxidation plateau was
obtained at higher temperatures. Reversible electrosorption of hydrogen is a useful reaction in supercapacitor performance
and it might have a potential application for a negative electrode of supercapacitor as well as reversibly operating electrode
in the secondary cell.
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19.
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
20.
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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