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1.
A very stable electroactive film of catechin was electrochemically deposited on the surface of activated glassy carbon electrode.
The electrochemical behavior of catechin modified glassy carbon electrode (CMGCE) was extensively studied using cyclic voltammetry.
The properties of the electrodeposited films, during preparation under different conditions, and the stability of the deposited
film were examined. The charge transfer coefficient (α) and charge transfer rate constant (k
s) for catechin deposited film were calculated. It was found that the modified electrode exhibited excellent electrocatalytic
activity toward hydrazine oxidation and it also showed a very large decrease in the overpotential for the oxidation of hydrazine.
The CMGCE was employed to study electrocatalytic oxidation of hydrazine using cyclic voltammetry, rotating disk voltammetry,
chronoamperometry, amperometry and square-wave voltammetry as diagnostic techniques. The catalytic rate constant of the modified
electrode for the oxidation of hydrazine was determined by cyclic voltammetry, chronoamperometry and rotating disk voltammetry
and was found to be around 10−3 cm s−1 . In the used different voltammetric methods, the plot of the electrocatalytic current versus hydrazine concentration is
constituted of two linear segments with different ranges of hydrazine concentration. Furthermore, amperometry in stirred solution
exhibits a detection limit of 0.165 μM and the precision of 4.7% for replicate measurements of 40.0 μM solution of hydrazine. 相似文献
2.
Pawel J. Kulesza Silvia Zamponi Marcin A. Malik Krzysztof Miecznikowski Mario Berrettoni Roberto Marassi 《Journal of Solid State Electrochemistry》1997,1(1):88-93
Using Prussian blue (PB) electrodeposited on gold-covered foil as a model system, we have demonstrated the usefulness of
the time-derivative measurements of absorbance versus potential (linear potential-scan voltabsorptometry) for spectroelectrochemical
characterization of thin electrochromic films. The time-derivative signals were monitored for PB at 680 and 420 nm in potassium,
sodium and lithium electrolytes. Information obtained from cyclic voltabsorptometry is equivalent or complementary to that
from conventional cyclic voltammetry. In the case of PB films investigated in lithium electrolyte, the voltabsorptometric
time-derivative peaks are better defined than the respective voltammetric peaks. The combination of voltabsorptometry with
voltammetry enables molar absorptivity and/or film loading to be determined. Also, concentration changes of differently colored
mixed-valence redox centers can be monitored as a function of applied potential.
Received: 16 January 1997 / Accepted: 11 March 1997 相似文献
3.
Ljubomir D. Arsov 《Journal of Solid State Electrochemistry》1998,2(4):266-272
The electrochemical synthesis of polyaniline on a titanium surface in aqueous sulfuric acid solutions with various concentrations
of added aniline has been investigated by cyclic voltammetry. By utilizing a more cathodic potential range (up to −0.6 V)
for the cyclization than is usual (up to −0.2 V) on Pt and Au electrodes, the new voltammetric waves have been deconvoluted
from the already well-known ones for polyaniline.
By simultaneous electrochemical and in situ Raman spectroscopic measurements, the Raman bands of polyaniline electrodeposited
on a Ti electrode, were assigned for potentials of −0.15 V and −0.6 V. It was found that the new monitored waves were closely
related to the so-called “middle” peaks and appear only when the polyaniline reaches an overoxidized state.
Received: 7 August 1997 / Accepted: 4 November 1997 相似文献
4.
Xiaofeng Zheng Han Xiao Tomonori Hoshi Jun-ichi Anzai Genxi Li 《Mikrochimica acta》2005,152(1-2):69-74
The voltammetric behavior of strychnine has been studied with a pyrolytic graphite (PG) electrode. The redox process taking
place at the PG electrode is discussed. The cyclic voltammetric response has also been evaluated with respect to various experimental
conditions, such as scan rate, pH of the supporting electrolyte, strychnine concentrations and accumulation time. A highly
sensitive voltammetric method for the determination of strychnine is consequently developed. The linear calibration is in
the range of 1×10−6 M – 1.1×10−4 M, with the limit of detection (LOD) being 1×10−8 M. The precision is excellent with a relative standard deviation (RSD) of 2.3%. The proposed cyclic voltammetric methodology
has been applied to the determination of strychnine in the extract of Strychno nux-vomica seeds using the standard addition method. Consistent results have been obtained from both the electrochemical approach described
here and the previously reported HPLC method. 相似文献
5.
Determination of Nitrite by a Modified Electrode of Poly(1-Naphthylamine) Film Doped with Dawson-Type Heteropolyanions 总被引:1,自引:0,他引:1
The voltammetric behavior of the electrode modified with poly(1-naphthylamine) film doped with α-P2W18 heteropolyanions was investigated. The concentration of the modifier, the acidity of the medium and the scan range of potential
had obvious effects on the electrochemical characteristics of the electrode. The electrocatalytical characteristics of the
film electrode were studied by cyclic voltammetry and other methods. It is suggested that the electrocatalytic reaction of
nitrite is controlled by its diffusion. The applicability of the electrode was assessed by the determination of nitrite in
waste-water. Determination limit for nitrite was 5 × 10−7 mol.L−1.
Received August 23, 1999. Revision January 2, 2001 相似文献
6.
Saeed Shahrokhian Hamid Reza Zare-Mehrjardi Habibollah Khajehsharifi 《Journal of Solid State Electrochemistry》2009,13(10):1567-1575
A chemically modified carbon-paste electrode (CPE) is prepared by incorporating congo red (CR) immobilized on multi-walled
carbon nanotube (MWCNT). The results show that CR is effectively immobilized on the surface of MWCNT under the ultrasonic
agitation in aqueous solution and further incorporating the nafion. The prepared electrode, due to the electrostatic repulsions
between the CR and ascorbate anion, is capable to mask the response of the ascorbic acid (AA) completely and provide an effective
method for the detection of minor amounts of uric acid (UA) in the presence of high concentrations of AA. On the other hand,
an increase in the microscopic area of the electrode by addition of MWCNT together with the electrocatalytic activity caused
to a significant enhancement in the voltammetric response to UA. Optimization of the amounts of composite modifier in the
matrix of CPE is performed by cyclic and differential pulse voltammetric measurements. The modified electrode shows a linear
response to UA in the range of 1.0 × 10−7–1.0 × 10−4 M with a detection limit of 1.0 × 10−8 M. The electrode exhibits excellent accuracies for the determination of UA in the presence of high concentrations of AA (a
recovery of 97.6%). The response of the electrode toward sulfhydryl compounds such as cysteine, penicillamine, and glutathione
is not considerable. This reveals a good selectivity for the voltammetric response toward UA. The effective electrocatalytic
property, ability for masking the voltammetric responses of the other biologically reducing agents, ease of preparation, and
surface regeneration by simple polishing together with high reproducibility and stability of the responses make the modified
electrode suitable for the selective and sensitive voltammetric detection of sub-micromolar amounts of UA in clinical and
pharmaceutical preparations. 相似文献
7.
Alain Walcarius Jérôme Devoy Jacques Bessiere 《Journal of Solid State Electrochemistry》2000,4(6):330-336
Pure silica particles were dispersed within carbon paste and the resulting modified electrode was applied to the selective
voltammetric detection of mercury(II) species after their accumulation at open circuit. The remarkable selectivity observed
between pH 4 and 7 was attributed to the intrinsic adsorption mechanism which involves a condensation reaction between mercury(II)
hydroxide and hydroxyl groups on the silica surface, leading to the formation of an inner-sphere-type surface complex. After
optimization with respect to the electrode composition, the detection medium, and the voltammetric scan mode, a linear response
was obtained in the concentration range between 2 × 10−7 M to 1 × 10−5 M, by applying anodic stripping square wave voltammetry. Various silica samples were used and their sorption behavior was
discussed in relation to their specific surface area and porosity. The effect of chloride and pH on the accumulation of mercury(II)
on silica was also investigated.
Received: 4 September 1999 / Accepted: 5 January 2000 相似文献
8.
Keith B. Oldham 《Journal of Solid State Electrochemistry》1998,2(6):367-377
When insoluble insulating crystals adhere to an electrode, the three-phase junction – where electrolyte solution, electrode
and crystal meet – is the only feasible site for an electrochemical reaction. Moreover, sustained reaction is possible only
if ions from the electrolyte solution are able to enter the crystal through the three-phase junction and disperse within the
crystal. Here, order-of-magnitude calculations demonstrate that diffusion to the three-phase junction is well able to support
voltammetry under standard experimental conditions. A model is built for cases of adherent cubes of uniform size and thereby
the shapes of chronoamperograms, chronograviograms and cyclic voltammograms are predicted. The model assumes that the ion
concentration at the three-phase junction plays a crucial role in the voltammetry, being determined by quasi-steady-state
ion diffusion from the bulk, the thermodynamics of the electrode reaction, and the extent to which the crystal has already
undergone reaction. Depending on the crystal size and scan rate, cyclic voltammograms may mimic solution-phase voltammograms
from classical thin-layer experiments or from typical stripping experiments. The effect of size heterogeneity on cyclic voltammetry
is simulated for lognormal distributions.
Received: 5 January 1998 / Accepted: 17 April 1998 相似文献
9.
A voltammetric sensor for the determination of parathion has been developed based on the use of a poly(carmine) film electrode.
The reduction of parathion at the poly(carmine) modified glassy carbon electrode (GCE) is studied by cyclic voltammetry (CV)
and linear scan voltammetry (LSV). Parathion yields a well-defined reduction peak at a potential of −0.595 V on the poly(carmine)
modified GCE in pH 6.0 phosphate buffer solution (PBS). Compared with that on a bare GCE, the reduction peak current of parathion
is significantly enhanced. All the experimental parameters are optimized for the determination of parathion. The reduction
peak current is linear with the parathion concentration in the range of 5.0 × 10−8 to 1.0 × 10−5 mol L−1, and the detection limit is 1.0 × 10−8 mol L−1. 相似文献
10.
Voltammetric Determination of Folic Acid with a Multi-Walled Carbon Nanotube-Modified Gold Electrode
The voltammetric behavior of folic acid (FA) at a multi-walled carbon nanotube (MWNT) modified gold electrode has been investigated
by cyclic voltammetry, chronoamperometry and chronocoulometry. The modified electrode exhibits a good promoting effect on
the electrochemical reaction of FA. FA can generate a well-defined anodic peak at around 0.83 V (vs. SCE) in 0.1 M H3PO4–NaH2PO4 buffer solution of pH 2.5. The peak results from a 2-electron transfer of FA, and the standard potential of FA is estimated
to be 0.79 V (vs. SCE). The parameters affecting the response of FA, such as solution pH, accumulation time, accumulation
potential, and amount of MWNTs are optimized for the determination of FA. Under the optimum conditions, the peak current changes
linearly with FA concentration in the range from 2.0 × 10−8 M to 1.0 × 10−6 M. This method has been applied to the determination of FA in drug tablets, and the recovery is 93.9–96.9%. In addition,
the influence of some coexistent species is examined. When a Nafion layer is introduced on the gold electrode before deposition
of MWNTs, the resulting composite electrode can give better response to FA. At the same time, the interference by some foreign
species is suppressed to some extent. 相似文献
11.
Alkaline solution, especially diphosphate solutions, can be used as electrolytes for the galvanic deposition of p-type semiconductors. A ternary Bi–Sb–Te alloy semiconductor was deposited at a Ni-covered cathode surface at potentials lower than −0.6 V (Ag/AgCl), under potentiostatic condition in well-stirred solutions. Additionally, it was possible to deposit antimony telluride, a binary p-semiconductor, from the ternary electrolyte. The kinetics of the process was investigated by cyclic voltammetric measurements. The influence of the electrolyte convection on the electrocrystallization was analysed with the help of rotating disc electrode. The semiconductor layers were characterized by electrochemical impedance spectroscopy.Paper presented at the Jahrestagung der Fachgruppe Angewandte Elektrochemie der Gesellschaft Deutscher Chemiker, Düsseldorf, 11.-14.09.2005 相似文献
12.
H. Karimi-Maleh A. A. Ensafi A. R. Allafchian 《Journal of Solid State Electrochemistry》2010,14(1):9-15
A ferrocenedicarboxylic acid modified carbon paste electrode was constructed and used as a fast and sensitive tool for the
determination of captopril at trace level. It has been shown by direct current cyclic voltammetry and double step chronoamperometry
that ferrocenedicarboxylic acid can catalyze the oxidation of captopril in aqueous buffer solution and produces a sharp oxidation
peak current at about +0.49 vs. Ag/AgCl reference electrode. The square wave voltammetric peak currents of the electrode increased
linearly with the corresponding captopril concentration in the range of 3.0 × 10−7–1.4 × 10−4M with a detection limit of 9.1 × 10−8 M. The influence of pH and potential interfering substances on the determination of captopril were studied. Electrochemical
impedance spectroscopy was used to study the charge transfer properties at the electrode–solution interface. Finally, the
sensor was examined as a selective, simple, and precise new electrochemical sensor for the determination of captopril in real
samples, such as drug and urine, with satisfactory results. 相似文献
13.
Covalent modification of a glassy carbon electrode with penicillamine for simultaneous determination of hydroquinone and catechol 总被引:1,自引:0,他引:1
Liang Wang Peng Fei Huang Jun Yue Bai Hong Jing Wang Li Ying Zhang Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):151-157
A simple and highly selective electrochemical method has been developed for the simultaneous determination of hydroquinone
(HQ) and catechol (CC) at a glassy carbon electrode covalently modified with penicillamine (Pen). The electrode is used for
the simultaneous electrochemical determination of HQ and CC and shows an excellent electrocatalytical effect on the oxidation
of HQ and CC upon cyclic voltammetry in acetate buffer solution of pH 5.0. In differential pulse voltammetric measurements,
the modified electrode was able to separate the oxidation peak potentials of HQ and CC present in binary mixtures by about
103 mV although the bare electrode gave a single broad response. The determination limit of HQ in the presence of 0.1 mmol L−1 CC was 1.0 × 10−6 mol L−1, and the determination limit of CC in the presence of 0.1 mmol L−1 HQ was 6.0 × 10−7 mol L−1. The method was applied to the simultaneous determination of HQ and CC in a water sample. It is simple and highly selective. 相似文献
14.
The electrochemical oxidation of thiocytosine on the surface of carbon-paste electrode modified with Schiff base (salophen
derivatives) complexes of cobalt is studied. The effect of the substituents in the structure of salophen on the catalytic
property of the modified electrode is investigated by using cyclic and differential pulse voltammetry. Cobalt (II)-5-nitrosalophen,
because of its electrophilic functional groups, leads to a considerable enhancement in the catalytic activity, sensitivity
(peak current), and a marked increase in the anodic potential of the modified electrode. The differential pulse voltammetry
is applied as a very sensitive method for the detection of thiocytosine. The linear dynamic range was between 1 × 10−3 to 4 × 10−6 M with a slope of 0.0168 μA/μM, and the detection limit was 1 × 10−6 M. The modified electrode is successfully applied for the voltammetric detection of thiocytosine in human synthetic serum
sample and also pharmaceutical preparations. A linear range from 1 × 10−3 to 1 × 10−5 M with a slope of 0.0175 μA/μM is resulted for the standard addition of thiocytosine spiked to the buffered human serum,
which is differing from the curve in buffer solution about 4%. The electrode has a very good reproducibility (relative standard
deviation for the slope of the calibration curve is less than 3.5% based on six determinations in a month), high stability
in its voltammetric response and low detection limit for thiocytosine, and high electrochemical sensitivity with respect to
other biological thiols such as cysteine. 相似文献
15.
The redox reactions of 2-mercaptobenzoxazole (MBO) have been investigated by cyclic voltammetry at glassy carbon electrodes
in aqueous solution. Four anodic and three cathodic processes could be identified. A more detailed analysis of the oxidation
processes up to a potential of +0.6 V (SCE) and the corresponding reduction signals showed that the oxidation leads to bis(benzoxazolyl)
disulfide (BBOD). Owing to its low solubility, the oxidation product remains at the electrode surface. This product has been
identified by ex situ FTIR and XPS analysis. During the reduction of BBOD, mainly MBO is formed. The remarkable lower solubility of BBOD in aqueous
solutions compared to MBO allows preparation of layers of BBOD in situ and to control the amount of deposited BBOD via the MBO solution concentration and electrolysis time. The peak potential
and peak shape of the reduction signals change remarkably as the amount of BBOD increases from submonolayer coverage to coverages
that correspond to multilayers. The behavior can be explained by assuming an electrochemical conversion of BBOD microcrystals,
which are deposited on the electrode surface, if the amount of BBOD formed during the MBO oxidation exceeds one monolayer.
Received: 21 January 1999 / Accepted: 15 March 1999 相似文献
16.
The voltammetric determination of 2-mercaptobenzimidazole (MBI) was studied by using a glassy carbon electrode (GCE) coated
with polymeric nickel and copper tetraaminophthalocyanine (poly-NiTAPc and poly-CuTAPc) membrane. The polymeric membrane decreases
the overpotential of oxidation of MBI by 136.2 and 115.0 mV and increases the oxidation peak current by about 3.4 and 3.3
times, while the reduction peak potential shifts positively by 113.0 and 84.1 mV and the peak current increases by about 10
and 7 times in 0.1 mol·l−1 phosphate buffer solution (PBS) at pH = 2.0 for poly-NiTAPc and poly-CuTAPc, respectively, compared to the unmodified GCE.
The results indicated that the developed electrode exhibited efficient electrocatalytic activity for MBI with relatively high
sensitivity, stability, and long life. The oxidation and reduction peak currents of MBI were linear to its concentrations
ranging from 8.0 × 10−5 to 1.0 × 10−3 mol·l−1 at poly-NiTAPc and from 2.0 × 10−5 to 1.0 × 10−3 mol·l−1 at poly-NiTAPc membranes modified electrodes, respectively, with a low limit of detection. 相似文献
17.
Voltammetric sensor for glutathione determination based on ferrocene-modified carbon paste electrode
Jahan Bakhsh Raoof Reza Ojani Mansureh Kolbadinezhad 《Journal of Solid State Electrochemistry》2009,13(9):1411-1416
The electrocatalytic oxidation of glutathione (GSH) has been studied at the surface of ferrocene-modified carbon paste electrode
(FMCPE). Cyclic voltammetry (CV), double potential step chronoamperometry, and differential pulse voltammetry (DPV) techniques
were used to investigate the suitability of incorporation of ferrocene into FMCPE as a mediator for the electrocatalytic oxidation
of GSH in buffered aqueous solution. Results showed that pH 7.00 is the most suitable for this purpose. In the optimum condition
(pH 7.00), the electrocatalytic ability of about 480 mV can be found and the heterogeneous rate constant of catalytic reaction
was calculated as . Also, the diffusion coefficient of glutathione, D, was found to be 3.61 × 10–5 cm2 s−1. The electrocatalytic oxidation peak current of glutathione at the surface of this modified electrode was linearly dependent
on the GSH concentration and the linear analytical curves were obtained in the ranges of 3.2 × 10–5 M–1.6 × 10–3 M and 2.2 × 10–6 M–3.5 × 10–3 M with cyclic voltammetry and differential pulse voltammetry methods, respectively. The detection limits (3σ) were determined as 1.8 × 10–5 M and 2.1 × 10–6 M using CV and DPV, respectively. Finally, the electrocatalytic oxidation of GSH at the surface of this modified electrode
can be employed as a new method for the voltammetric determination of glutathione in real samples such as human plasma. 相似文献
18.
Sayed Medhi Ghoreishi Mohsen Behpour Mohammad Hassan Motaghedi Fard 《Journal of Solid State Electrochemistry》2012,16(1):179-189
In this work, we investigate the electrochemical activity of dopamine (DA) and uric acid (UA) using both a bare and a modified
carbon paste electrode as the working electrode, with a platinum wire as the counter electrode and a silver/silver chloride
(Ag/AgCl) as the reference electrode. The modified carbon paste electrode consists of multi-walled carbon nanotubes (>95%)
treated with α-cyclodextrine, resulting in an electrode that exhibits a significant catalytic effect toward the electro-chemical
oxidation of DA in a 0.2-M Britton–Robinson buffer solution (pH 5.0). The peak current increases linearly with the DA concentration
within the molar concentration ranges of 2.0 × 10−6 to 5.0 × 10−5 M and 5.0 × 10−5 to 1.9 × 10−4 M. The detection limit (signal to noise >3) for DA was found to be 1.34 × 10−7 M, respectively. In this work, voltammetric methods such as cyclic voltammetry, chronoamperometry, chronocuolometry, differential
pulse and square wave voltammetry, and linear sweep and hydrodynamic voltammetry were used. Cyclic voltammetry was used to
investigate the redox properties of the modified electrode at various scan rates. The diffusion coefficient (D, cm2 s−1 = 3.05 × 10−5) and the kinetic parameters such as the electron transfer coefficient (α = 0.51) and the rate constant (k, cm3 mol−1 s−1 = 1.8 × 103) for DA were determined using electrochemical approaches. By using differential pulse voltammetry for simultaneous measurements,
we obtained two peaks for DA and UA in the same solution, with the peak separation approximately 136 mV. The average recovery
was measured at 102.45% for DA injection. 相似文献
19.
Maryam Khoshroo Abbas A. Rostami Saeed Yeganegi 《Monatshefte für Chemie / Chemical Monthly》2008,139(7):781-787
A glassy carbon (GC) surface modified with monolayer of 4-bromophenyl was examined as voltammetric electrode for some redox
systems. The modified electrode exhibited very slow electron transfer in comparison to the unmodified surface by factors which
varied with the redox systems. However, after scanning the modified electrode in 0.1 M tetrabutylammonium tetrafluoroborate (TBABF4) in acetonitrile from 0.4 to −1.1 V vs. Ag/AgCl for 20–25 cycles, the modified electrode showed much faster electron transfer kinetics, e.g., the results for Fe(CN)6
3−/4− were approaching those observed with unmodified surfaces. The effect is attributed to an apparently irreversible structural
change in the 4-bromophenyl monolayer, which increases the rate of electron tunneling. The transition to the conducting state
is associated with electron injection into the monolayer and causes a significant decrease in the calculated HOMO-LUMO gap
for the monolayer molecule. Once the monolayer is switched to the conducting state, it supports rapid electron exchange with
the redox system, but not with dopamine, which requires adsorption to the electrode surface. A conductive surface modified
electrode may have useful properties for electroanalytical applications and possibly in electrocatalysis.
Correspondence: Abbas A. Rostami, Department of Chemistry, Faculty Basic of Science, University of Mazandaran, Babolsar, Iran. 相似文献
20.
A square wave adsorptive stripping voltammetric (SWAdSV) method was developed for the determination of proflavine. The electrochemical
behaviour of proflavine was investigated by cyclic (CV) and square wave voltammetry (SWV) at the hanging mercury drop electrode
(HMDE) and carbon paste electrode (CPE). Different parameters were tested to optimize the conditions of the determination.
Better results were obtained by square wave voltammetry using CPE where two oxidation and a reduction peak, appeared, at 0.19,
0.94 and 0.20 V, respectively. The peak at 0.19 V is quasi-reversible and deposition dependent. Linearity was observed in
the range of (0.2–23.4) × 10−8 M (r = 0.998) during the anodic scan and in the range of (1.17–117) × 10−8 M (r = 0.999) during the cathodic scan. The second peak at 0.94 V is irreversible and deposition independent. The linearity of
this peak was observed in the range of (1.29–11.7) × 10−8 M (r = 0.998). The method was applied to the analysis of bovine serum and gave satisfactory results.
Correspondence: S. Th. Girousi, Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki
54124, Greece 相似文献