共查询到20条相似文献,搜索用时 765 毫秒
1.
Guzel Ziyatdinova Aliya Gainetdinova Mikhail Morozov Herman Budnikov Svetlana Grazhulene Arkady Red’kin 《Journal of Solid State Electrochemistry》2012,16(1):127-134
Glassy carbon electrodes (GCE) modified with carbon nanotubes (CNT) have been created for detection of phenolic compounds—one
of the important group of antioxidants in life sciences. The surface of electrode has been characterized by atomic force microscopy.
The presence of CNT leads to an at least 20-fold increase in the surface roughness of the electrode. The CNT layer displays
closely intertwined vermicular structures with high degree of homogeneity at CNT suspension concentration of 0.2–0.5 mg L−1. Synthetic water-soluble antioxidants (hydroquinone, catechol, pyrogallol, and their derivatives) are electrochemically active
on bare GCE and CNT-modified GCE in phosphate buffer solution pH 7.4. Effect of substitutes in molecular structure of phenolic
antioxidants has been evaluated. In several cases, oxidation at CNT-modified GCE occurs at potentials that are less positive
by 100–200 mV in comparison to bare GCE. The electrodes were studied with respect to their capability of phenols voltammetric
sensing. CNT-modified GCE display an enlarged linear range in the calibration graphs and lower detection limits. Voltammetric
method for determination of hydroquinone, catechol, pyrogallol, and their derivatives has been developed. 相似文献
2.
For electrocatalytic determination of NADH, a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion
nanocomposite was proposed. The composition of the matrix film was optimised in terms of the content of carbon nanotubes and
Nafion. Incorporation of a redox mediator, Meldola’s Blue, into the nanocomposite film enabled electrocatalytic determination
of NADH at a low potential, −50 mV. For determination of ethanol, alcohol dehydrogenase (ADH) was immobilized into the matrix
layer. Experimental conditions affecting the biosensor response were examined, including enzyme loading, temperature of measurement
and pH of background electrolyte. Assessments of the analytical characteristics of the biosensor were performed with respect
to sensitivity, limit of detection, operational stability, repeatability and reproducibility. The proposed biosensor showed
electrocatalytic activity toward oxidation of ethanol with sensitivity of 2.24 μA L mmol−1, linear range from 0.05 to 1.1 mmol L−1, and limit of detection of 25 μmol L−1. The apparent Michaelis-Menten constant was 1.24 mmol L−1, indicating a high biological affinity of ADH/titania sol-gel/Meldola’s Blue/MWCNT/Nafion electrode for ethanol. The developed
biosensor was tested in determinations of ethanol content in alcoholic beverages. 相似文献
3.
Chunya Li 《Mikrochimica acta》2007,157(1-2):21-26
Multi-wall carbon nanotubes (MWNT) were dispersed into water in the presence of dicetyl phosphate (DCP), and MWNT-DCP composite
film coated glassy carbon electrodes (GCE) were constructed. The electrochemical properties of 2-chlorophenol at a bare GCE
and MWNT-DCP modified GCE were compared. It was found that MWNT-DCP modified GCEs significantly enhance the oxidation peak
current of 2-chlorophenol and lowers its oxidation overpotential, suggesting great potential in the sensitive determination
of 2-chlorophenol. Finally, a sensitive and simple voltammetric method was developed for the determination of 2-chlorophenol.
The oxidation peak current increases linearly with the concentration in the range of 1.0 × 10−7–2.0 × 10−5 mol L−1, and the detection limit is 4.0 × 10−8 mol L−1 for 2 min accumulation. The method was successfully used to determine 2-chlorophenol in waste water samples. 相似文献
4.
E. Nazaruk K. Sadowska J. F. Biernat J. Rogalski G. Ginalska R. Bilewicz 《Analytical and bioanalytical chemistry》2010,398(4):1651-1660
Nanostructured bioelectrodes were designed and assembled into a biofuel cell with no separating membrane. The glassy carbon
electrodes were modified with mediator-functionalized carbon nanotubes. Ferrocene (Fc) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate)
diammonium salt (ABTS) bound chemically to the carbon nanotubes were found useful as mediators of the enzyme catalyzed electrode
processes. Glucose oxidase from Aspergillus niger AM-11 and laccase from Cerrena unicolor C-139 were incorporated in a liquid-crystalline matrix-monoolein cubic phase. The carbon nanotubes–nanostructured electrode
surface was covered with the cubic phase film containing the enzyme and acted as the catalytic surface for the oxidation of
glucose and reduction of oxygen. Thanks to the mediating role of derivatized nanotubes the catalysis was almost ten times
more efficient than on the GCE electrodes: catalytic current of glucose oxidation was 1 mA cm−2 and oxygen reduction current exceeded 0.6 mA cm−2. The open circuit voltage of the biofuel cell was 0.43 V. Application of carbon nanotubes increased the maximum power output
of the constructed biofuel cell to 100 μW cm−2 without stirring of the solution which was ca. 100 times more efficient than using the same bioelectrodes without nanotubes
on the electrode surface. 相似文献
5.
A novel modified electrode was fabricated by electropolymerization of acid chrome blue K at a multi-walled carbon nanotubes
modified glassy carbon electrode. The electrode developed was used for simultaneous determination of the isomers of dihydroxybenzene
in environmental samples using first order linear sweep derivative voltammetry with background subtraction. A linear relationship
between peak current and concentration of hydroquinone, catechol and resorcinol was obtained in the range of 1 × 10−6–1 × 10−4 mol L−1, and the detection limits were estimated to be 1 × 10−7, 1 × 10−7 and 9 × 10−8 mol L−1, respectively. The constructed electrode showed excellent reproducibility and stability. Real water samples were analyzed
and satisfactory results were obtained. This method provides a new way of constructing electrodes for environmental and biological
analysis. 相似文献
6.
This work reports on the performance of new glucose biosensors based on the combination of the electrocatalytic properties
of metals and carbon nanotubes towards the reduction of hydrogen peroxide with the biocatalytic activity of glucose oxidase
(GOx). The bioelectrodes were obtained by dispersing the metal particles, enzyme and multi-wall carbon nanotubes within a
mineral oil binder. The strong electrocatalytic activity of copper and iridium towards the reduction of hydrogen peroxide
has made possible an important improvement in the sensitivity for the determination of glucose compared to the carbon nanotube
composite without metals. A highly sensitive and selective amperometric detection of glucose becomes possible at very low
potentials (−0.100 V). The presence of the protein enables a better dispersion of the metals within the composite matrix,
thus allowing an additional enhancement in the response to hydrogen peroxide. The influence of the amount of copper in the
composite on the analytical performance of the bioelectrode is discussed. A biosensor containing 0.77% w/w Cu and 10.0% w/w
GOx gave a fast response (10.0 s), a linear relationship between current and glucose concentration up to 1.20 × 10−2 M, and a detection limit of 2.0 × 10−5 M. A similar behavior was found for a carbon nanotube-composite electrode containing iridium. 相似文献
7.
An ensemble of carbon fibers ultra-microelectrode modified with carbon nanotubes (EUME-CNTS) has been constructed based on
a thin carbon nanotubes film which was coated onto surfaces of carbon fibers of ultra-microelectrode. SEM micrographs illustrated
the image of carbon nanotubes on the carbon fiber surface. The electrochemical characteristics of the EUME-CNTS has been investigated
by cyclic voltammetry. The electrochemical properties of dopamine on this electrode were also studied, and the detection limit
was found to be 2.0 × 10−9 mol·L−1. Linear calibration plots were obtained for the oxidation peak current in a range 1.0 × 10−7–8.0 × 10−5 mol·L−1.
Correspondence: Xiuhua Liu, Kuaizhi Liu, Department of Chemistry and Chemical Engineering, Henan University, Henan Kaifeng
475001, P.R. China 相似文献
8.
A simple, sensitive, and reliable method based on a combination of multi-walled carbon nanotubes with incorporated β-cyclodextrin
(β-CD-MWNTs) and a polyaniline (PANI) film-modified glassy-carbon (GC) electrode has been successfully developed for determination
of dopamine (DA) in the presence of ascorbic acid (AA). The PANI film had good anti-interference properties and long-term
stability, because of the permselective and protective properties of the conducting redox polymer film. The acid-treated MWNTs
with carboxylic acid functional groups promoted the electron-transfer reaction of DA and inhibited the voltammetric response
of AA. Sensitive detection of DA was further improved by the preconcentration effect of formation of a supramolecular complex
between β-CD and DA. The analytical response of the β-CD-MWNTs/PANI film to the electrochemical behavior of DA was, therefore,
better than that of a MWNTs/PANI film, a PANI film, or a bare glassy-carbon (GC) electrode. Under the conditions chosen a
linear calibration plot was obtained in the range 1.0 × 10−7–1.0 × 10−3 mol L−1 and the detection limit was 1.2 × 10−8 mol L−1. Interference from AA was effectively eliminated and the sensitivity, selectivity, stability, and reproducibility of the
electrodes was excellent for determination of DA. 相似文献
9.
Single-wall carbon nanotubes (SWNT) were dispersed into water in the presence of dicetyl phosphate (DCP), and then a SWNT-DCP
film-coated glassy carbon electrode (GCE) was constructed. The electrochemical behavior of acetaminophen at bare GCE and SWNT-DCP
modified GCE were compared, suggesting that the SWNT-DCP-modified GCE significantly enhances the oxidation peak current of
acetaminophen. A sensitive and simple electrochemical method with a good linear relationship in the range of 1.0 × 10−7–2.0 × 10−5 mol L−1, was developed for the determination of acetaminophen. The detection limit is 4.0 × 10−8 mol L−1 for 3-min accumulation. This method was successfully demonstrated with tablets. 相似文献
10.
Acetylcholinesterase-based biosensors for quantification of carbofuran, carbaryl, methylparaoxon, and dichlorvos in 5% acetonitrile 总被引:1,自引:0,他引:1
Valdés-Ramírez G Cortina M Ramírez-Silva MT Marty JL 《Analytical and bioanalytical chemistry》2008,392(4):699-707
Amperometric acetylcholinesterase biosensors have been developed for quantification of the pesticides carbofuran, carbaryl,
methylparaoxon, and dichlorvos in phosphate buffer containing 5% acetonitrile. Three different biosensors were built using
three different acetylcholinesterase (AChE) enzymes—AChE from electric eel, and genetically engineered (B394) and wild-type
(B1) AChE from Drosophila melanogaster. Enzymes were immobilized on cobalt(II) phthalocyanine-modified electrodes by entrapment in a photocrosslinkable polymer
(PVA-AWP). Each biosensor was tested against the four pesticides. Good operational stability, immobilisation reproducibility,
and storage stability were obtained for each biosensor. The best detection limits were obtained with the B394 enzyme for dichlorvos
and methylparaoxon (9.6 × 10−11 and 2.7 × 10−9 mol L−1, respectively), the B1 enzyme for carbofuran (4.5 × 10−9 mol L−1), and both the B1 enzyme and the AChE from electric eel for carbaryl (1.6 × 10−7 mol L−1). Finally, the biosensors were used for the direct detection of the pesticides in spiked apple samples. 相似文献
11.
A method for the determination of trace clenbuterol is described. Multi-walled carbon nanotubes (MWCNTs)-Nafion composite
was used to modify the glassy carbon electrode (GCE). The modified electrode showed high sensitivity and good selectivity
for clenbuterol detection. It offered a linear range of 1.0 × 10−9–1.0 × 10−6 mol · L−1 with a detection limit of 5.0 × 10−10 mol · L−1 in pH = 1.2 solution. The oxidation mechanism of clenbuterol on the electrode was also investigated.
Correspondence: Xiao-Ya Hu, Department of Chemistry, Yang Zhou University, Yang Zhou, Jiang Su, P.R. China 相似文献
12.
Tian XJ Song JF Luan XJ Wang YY Shi QZ 《Analytical and bioanalytical chemistry》2006,386(7-8):2081-2086
Molecular wires containing copper(II) (CuMW), in the form of the coordination polymer (Cu(II)4(bpp)4(maa)8(H2O)2).2H2O (bpp=1,3-bis(4-pyridyl)propane, maa=2-methylacrylic acid), and multiwalled carbon nanotubes (CNT) have been combined to
prepare a paste electrode (CuMW/CNT/PE). The voltammetric response of the CuMW/CNT/PE to metformin (MET) was significantly
greater than that of electrodes prepared from other materials, because of both the surface effect of CuMW and CNT and coordination
of MET with the Cu(II) ion in the CuMW. A novel voltammetric method for determination of MET is proposed. In pH 7.2 Britton–Robinson
buffer, using single sweep voltammetry, the second-order derivative peak current for oxidation of MET at 0.97 V (relative
to SCE) increased linearly with MET concentration in the range 9.0 × 10−7–5.0 × 10−5 mol L−1 and the detection limit was 6.5 × 10−7 mol L−1.
Figure When a combination of molecular wires containing copper(II) (CuMW) and multiwalled carbon nanotubes (CNT) was used to prepare
a paste electrode (CuMW/CNT/PE) the voltammetric response to metformin (curve c) was significantly higher than that at a carbon/PE
(curve a) or a CNT/PE (curve b), because of the amplification effect of CNT and CuMW. A novel voltammetric method is proposed
for determination of MET 相似文献
13.
R. Chandrasekaran Y. Soneda J. Yamashita M. Kodama H. Hatori 《Journal of Solid State Electrochemistry》2008,12(10):1349-1355
The effect of polymer–salt addition in the activated carbon electrode for electric double-layer capacitor (EDLC) has been
investigated. A series of composite thin film electrode consisting of activated carbon, carbon black, polytetrafluoroethylene
and polymer–salt complex (polyethyleneoxide–LiClO4) with an appropriate weight ratio were prepared and examined their performance for EDLCs using 1 mol L−1 LiClO4 in ethylene carbonate:diethylcarbonate electrolyte solution. The electrochemical capacitance performances of these electrodes
with different compositions were characterized by cyclic voltammetry, galvanostatic charge–discharge cycling, and AC impedance
measurements. By comparison, the best results were obtained with a composite electrode rich in polymer–salt additive (132 F
g−1 at 100 mA g−1 of galvanostatic experiment). In general, the polymer–salt-containing electrode had shown improved performance over activated
carbon electrodes without polymer–salt at high current density. 相似文献
14.
Abolanle S. Adekunle Kenneth I. Ozoemena 《Journal of Solid State Electrochemistry》2008,12(10):1325-1336
Electrochemistry of edge-plane pyrolytic graphite electrodes (EPPGEs) modified with Aldrich single-walled carbon nanotubes
(SWCNTs) electro-decorated with metal (Ni, Fe and Co) and their oxides have been studied. The morphology and identity of the
metallic dispersions were examined by scanning electron microscopy and energy-dispersive spectroscopy. We show that SWCNTs
serve as efficient conducting carbon material for electronic communication between metal films and the underlying carbon electrode.
By using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques, it is proved that both EPPGE-SWCNT-Ni
and EPPGE-SWCNT-Fe exhibit comparable electrochemical response in buffered aqueous solution (pH 7.0) and towards electro-oxidation
of hydrazine in Na2SO4 solution. The impedance spectra of these SWCNT-metal hybrids were complicated and follow electrical equivalent circuit model
typical of adsorption-controlled charge transfer kinetics. Hydrazine impedance spectra exhibited inductive loop, characteristic
of Faradaic current being governed by the occupation of an intermediate state. On the other hand, the EIS data obtained in
a simple redox probe, [Fe(CN)6]3−/[Fe(CN)6]4−, showed that EPPGE-SWCNT and EPPGE-SWCNT-Ni followed electrical equivalent circuit models typical of partial charge transfer
or adsorption-controlled kinetics with some resemblance to the behaviour of electrolyte–insulator–semiconductor sensors. 相似文献
15.
High performance liquid chromatography coupled with microdialysis sampling and electrochemical detection (HPLC–ECD) has been
used to determine dopamine (DA). In the HPLC–ECD a multi-wall carbon nanotube electrode chemically modified with carboxyl
groups (MWNT-COOH CME) was used as the working electrode for determination of DA. The results indicated that the MWNT-COOH
CME enabled efficient electrocatalytic oxidation of DA with relatively high sensitivity and stability and long life. Peak
currents for dopamine were linearly dependent on concentration in the range 5.0×10−9 to 5.0×10−5 mol L−1 and the calculated detection limit (S/N=3) was 2.5×10−9 mol L−1. The method had been successfully used to measure dopamine in rat striatal microdialysate. To study the physiological effect
of nitric oxide (NO) on striatal release of DA, 0.5 mmol L−1 sodium nitroprusside (SNP) was a continuously perfused into rat striatum. This resulted in a 46% increase in DA basal level. 相似文献
16.
SiO2/Sb2O3 (SiSb), having a specific surface area, S
BET, of 788 m2 g−1, an average pore diameter of 1.9 nm and 4.7 wt% of Sb, was prepared by the sol-gel processing method. Meldola's blue (MeB),
methylene blue (MB) and toluidine blue (TB) were immobilized on SiSb by an ion exchange reaction. The amounts of the dyes
bonded to the substrate surface were 12.49, 14.26 and 22.78 μmol g−1 for MeB, MB and TB, respectively. These materials were used to modify carbon paste electrodes. The midpoint potentials (E
m) of the immobilized dyes were −0.059, −0.17 and −0.18 V vs. SCE for SiSb/MeB, SiSb/MB and SiSb/TB modified carbon paste electrodes,
respectively. A solution pH between 3 and 7 practically did not affect the midpoint potential of the immobilized dyes. The
electrodes presented reproducible responses and were chemically stable under various oxidation-reduction cycles. Among the
immobilized dyes, MeB was the most efficient to mediate the electron transfer for NADH oxidation in aqueous solution at pH 7.
In this case, amperometric detection of NADH at an applied potential of 0 mV vs. SCE gives linear responses over the concentration
range of 0.1–0.6 mmol L−1, with a detection limit of 7 μmol L−1. 相似文献
17.
An electrochemical study of the doxazosin oxidative process at carbon paste electrodes using different voltammetric techniques
has been carried out. The process is irreversible and controlled by adsorption, giving rise to an oxidation wave around 1.0 V
in citric acid-citrate buffer (pH 3.0). A mechanism based on the oxidation of the amine group is postulated. Two methods based
on adsorptive stripping (AdS) of doxazosin at the C8-modified carbon paste electrode (C8-MCPE), before its voltammetric determination, are studied, using differential pulse voltammetry (DPV) and square wave voltammetry
(SWV) as redissolution techniques. By means of AdS-DPV and C8-MCPE, doxazosin can be determined over the 1.0 × 10−9 to 3.0 × 10−8 mol L−1 range with a variation coefficient of 2.2% (2.0 × 10−8 mol L−1) and a limit of detection of 7.4 ×10−10 mol L−1. If AdS-SWV is used, a linear range from 1.0 × 10−9 to 4.0 × 10−8 mol L−1 is obtained, the variation coefficient being 2.8% (2.0 × 10−8 mol L−1, and the limit of detection reached 7.7 × 10−10 mol L−1. The AdS-DPV procedure was applied to the determination of doxazosin in urine and formulations.
Received March 13, 1999. Revision December 23, 1999. 相似文献
18.
Amereih S Meisel T Kahr E Wegscheider W 《Analytical and bioanalytical chemistry》2005,383(7-8):1052-1059
Speciation analysis of Sb(III) and Sb(V) in a soil sample was performed through extraction and on-line isotope dilution concentration
determination after a chromatographic separation. The total Sb concentration found in a through traffic contaminated soil
sample was (4.17 μg g−1, 0.3 μg g−1 SD, n=6). It was determined using ICP-MS after soil digestion using the sodium peroxide sintering method. The optimized extraction
procedure for speciation analysis was carried out using 100 mmol L−1 citric acid at pH 2.08 by applying an ultrasonic bath for 45 min at room temperature. The effects of citric acid concentration
(0–500 mmol L−1), pH (1–6), and temperature (30–60°C) on inorganic antimony species distribution in the examined sample were studied and
optimized. The separation of Sb(III) and Sb(V) was achieved using an anion exchange column (PRP-X100) and 10 mmol L−1 EDTA and 1 mmol L−1 phthalic acid at pH 4.5 as a mobile phase. The eluent from the HPLC was mixed with an enriched (94.2%) 123Sb spike solution that was pumped by a peristaltic pump with a constant flow rate (0.5 mL min−1) in a three-way valve. The blend passed directly to the Conikal nebulizer of the ICP-MS. By using the above extraction procedure
and methodology, 43.2% Sb(V) (2.9% RSD, n=3) and 6.0% Sb(III) (1.3% RSD, n=3) of total Sb found in the sample could be detected. The detection limits achieved by the proposed method were 20 ng L−1 and 65 ng L−1 for Sb(V) and Sb(III), respectively. The precision, evaluated by using RSD with 100 ng L−1 calibration solutions, was 2.7% and 3.2% (n=6) for Sb(V) and Sb(III), respectively, in aqueous solutions. 相似文献
19.
Multi-wall carbon nanotubes (MWNT) have been dispersed into water with the emulsification of oil of turpentine and emulsifier
OP TX-100. An MWNT-modified glassy carbon electrode (GCE) has been achieved through solvent evaporation of MWNT- dispersion.
In pH 2.0 phosphate buffer, MWNT- modified GCE has an obvious catalytic effect on the oxidation of estradiol, estrone and
estriol. The oxidation peak current of these estrogens at the modified electrode increases significantly in contrast with
that at the bare GCE. The experimental conditions which heavily affect the oxidation peak current of estradiol, such as the
solution pH, the amount of MWNT, the scan rate, the adsorption potential and adsorption time, were optimized. The peak current
is linear to the concentration in the range of 2.5 × 10−7 to 5 × 10−5 mol L−1 estradiol. The detection limit is 1 × 10−8 mol L−1 after 3 min open-circuit adsorption. The relative standard deviation (RSD) of six measurements using an electrode is 3.2%
for 1 × 10−5 mol L−1 estradiol. The effect of interferences of other organic compounds on the determination of estradiol was examined.
Author for correspondence: Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China. E-mail: sshu@whu.edu.cn
Received June 19, 2002; accepted January 4, 2003
Published online April 11, 2003 相似文献
20.
Ying Xu Fei Wang Le Wang Fangyuan Zhao Baocheng Yang Baoxian Ye 《Journal of Solid State Electrochemistry》2012,16(4):1473-1480
A novel voltammetric sensor, based on single-walled carbon nanotubes (SWNT) dispersed in Nafion and modified glassy carbon
electrode (GCE), was fabricated and used to determine the trace amounts of dihydromyricetin (DMY). The electrochemical behavior
of DMY at this sensor was investigated in 0.1 mol L−1 sulfuric acid solutions + 0.1 mol L−1 NaCl by cyclic voltammetry and squarewave voltammetry. Compared with bare GCE, the electrode presented an excellent response
of DMY through an adsorption-controlled quasi-reversible process. Under the optimum conditions, the response peak currents
were linear relationship with the DMY concentrations in the range of 1.0 × 10−7–1.0 × 10−5 mol L−1 with a detection limit of 9 × 10−8 mol L−1. Based on this voltammetric sensor, a simple and sensitive electroanalytical method for DMY was proposed and applied to quantitative
determination of DMY in Ampelopsis grossedentata samples. In addition, the oxidation mechanism was proposed and discussed, which could be a reference for the pharmacological
action of DMY in clinical study. 相似文献