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1.
A carbon ionic liquid electrode (CILE) was fabricated by mixing N-butylpyridinium hexafluoro-phosphate (BPPF
6
) with graphite powder and further used for the investigation on the electrochemical behavior of L-tryptophan (Trp). The fabricated CILE showed good conductivity, inherent electrocatalytic ability and strong promotion to the electron transfer
of Trp. On the CILE, an irreversible oxidation peak appeared at 0.948 V (vs. saturated calomel reference electrode). For 5.0
× 10−5 M Trp the oxidation peak current increased about 5 times and the oxidation peak potential decreased on 0.092 V compared to
carbon paste electrode. The results indicated that an electrocatalytic reaction occurred on CILE. The conditions for the electrochemical
detection were optimized and the electrochemical parameters of Trp on CILE were carefully investigated. Under the selected
conditions, the oxidation peak current showed linear relationship with Trp concentration in the range of 8.0 × 10−6 ∼1.0 × 10−3 M for cyclic voltammetry and the detection limit was estimated as 4.8 × 10−6 M (3σ). The interferences of other amino acids or metal ions on the determination were tested and the proposed method was
successfully applied to the synthetic sample analysis. 相似文献
2.
A highly sensitive hydroxylamine (HA) electrochemical sensor is developed based on electrodeposition of gold nanoparticles
with diameter of 8 nm on the pre-synthesized polypyrrole matrix and formed gold nanoparticles/polypyrrole (GNPs/PPy) composite
on glassy carbon electrode. The electrochemical behavior and electrocatalytic activity of the composite-modified electrode
are investigated. The GNPs/PPy composite exhibits a distinctly higher electrocatalytic activity for the oxidation of HA than
GNPs with twofold enhancement of peak current. The enhanced electrocatalytic activity is attributed to the synergic effect
of the highly dispersed gold metal particles and PPy matrix. The overall numbers of electrons involved in HA oxidation, the
electron transfer coefficient, catalytic rate constant, and diffusion coefficient are investigated by chronoamperometry. The
sensor presents two wide linear ranges of 4.5 × 10−7–1.2 × 10−3 M and 1.2 × 10−3–19 × 10−3 M with the detection limit of 4.5 × 10−8 M (s/n = 3). In addition, the proposed electrode shows excellent sensitivity, selectivity, reproducibility, and stability properties. 相似文献
3.
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
4.
Xiaomei Cao Yanhong Xu Liqiang Luo Yaping Ding Ying Zhang 《Journal of Solid State Electrochemistry》2010,14(5):829-834
A glassy carbon electrode (GCE) modified with the film composed of chitosan incorporating cetylpyridine bromide is constructed
and used to determine uric acid (UA) and ascorbic acid (AA) by differential pulse voltammetry (DPV). This modified electrode
shows efficient electrocatalytic activity and fairly selective separation for oxidation of AA and UA in mixture solution.
UA is catalyzed by this modified electrode in phosphate buffer solution (pH 4.0) with a decrease of 80 mV, while AA is catalyzed
with a decrease of 200 mV in overpotential compared to GCE, and the peak separation of oxidation between AA and UA is 260
mV, which is large enough to allow the determination of one in presence of the other. Under the optimum conditions, the anodic
peak currents (I
pa) of DPV are proportional to the concentration of UA in the range of 2.0 × 10−6 to 6.0 × 10−4 M, with the detection limit of 5.0 × 10−7 M at a signal-to-noise ratio of 3 (S/N = 3) and to that of AA in the range of 4.0 × 10−6 to 1.0 × 10−3 M, with the detection limit of 8.0 × 10−7 M (S/N = 3). 相似文献
5.
The electrocatalytic oxidation of quinine sulfate (QS) was investigated at a glassy carbon electrode, modified by a gel containing
multiwall carbon nanotubes (MWCNTs) and room-temperature ionic liquid of 1-Butyl-3-methylimidazolium hexafluorophate (BMIMPF6) in 0.10 M of phosphate buffer solution (PBS, pH 6.8). It was found that an irreversible anodic oxidation peak of QS with
E
pa as 0.99 V appeared at MWCNTs-RTIL/glassy carbon electrode (GCE). The electrode reaction process was a diffusion-controlled
one and the electrochemical oxidation involved two electrons transferring and two protons participation. Furthermore, the
charge-transfer coefficient (α), diffusion coefficient (D), and electrode reaction rate constant (k
f) of QS were found to be 0.87, 7.89 × 10−3 cm2⋅s−1 and 3.43 × 10−2 s−1, respectively. Under optimized conditions, linear calibration curves were obtained over the QS concentration range 3.0 × 10−6 to 1.0 × 10−4 M by square wave voltammetry, and the detection limit was found to be 0.44 μM based on the signal-to-noise ratio of 3. In
addition, the novel MWCNTs-RTIL/GCE was characterized by the electrochemical impedance spectroscopy and the proposed method
has been successfully applied in the electrochemical quantitative determination of quinine content in commercial injection
samples and the determination results could meet the requirement. 相似文献
6.
Chunhai Yang Shenghui Zhang Yingxuan Liu Wensheng Huang 《Frontiers of Chemistry in China》2008,3(3):353-358
A multi-wall carbon nanotubes (MWNTs)-Nafion film-coated glassy carbon electrode (GCE) was fabricated and the electrochemical
behavior of ofloxacin on the MWNTs-Nafion film-coated GCE were investigated by cyclic voltammetry (CV), linear sweep voltammetry
(LSV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current of ofloxacin increased significantly on
the MWNTs-Nafion film modified GCE compared with that using a bare GCE. This nano-structured film electrode exhibited excellent
enhancement effects on the electrochemical oxidation of ofloxacin. A well-defined oxidation peak attributed to ofloxacin was
observed at 0.97 V and was applied to the determination of ofloxacin. The oxidation peak current was proportional to ofloxacin concentration
in the ranges 1.0 × 10−8 to 1.0 × 10−6 mol/L and 1.0 × 10−6 to 2.0 × 10−5 mol/L. A detection limit of 8.0 × 10−9 mol/L was obtained for 400 s accumulation at open circuit (S/N = 3). This method for the detection of ofloxacin in human
urine was satisfactory.
__________
Translated from Chinese Journal of Applied Chemistry, 2007, 24(5): 540–545 [译自: 应用化学] 相似文献
7.
A sensitive and selective electrochemical method for the determination of norepinephrine using a poly (Evans Blue) film-modified
glassy carbon electrode was developed. The polymer film-modified electrode shows excellent electrocatalytic activity toward
the oxidation of norepinephrine (NE) in phosphate buffer solution (pH 5.0). The linear range of 5.0 × 10−7–1.8 × 10−5 M and detection limit of 3.5 × 10−8 M were observed for the determination of NE in pH 5.0 phosphate buffer solutions. The interference studies showed that the
modified electrode had excellent selectivity for the determination of NE in the presence of large excess of ascorbic acid
(AA) and uric acid (UA). The differences of the oxidation peak potentials for NE-AA and NE-UA were about 175 and 172 mV, respectively. The resolution
is large enough to determine AA, NE and UA individually. This work provides a simple and easy approach to selective detection
of NE in the presence of AA and UA in physiological samples.
The article is published in the original. 相似文献
8.
Gang Li Suling Yang Lingbo Qu Ran Yang Jianjun Li 《Journal of Solid State Electrochemistry》2011,15(1):161-166
A Nafion/multi-wall carbon nanotubes (MWNT) composite film-modified electrode was fabricated. The modified electrode showed
excellent electrocatalytic activity toward ascorbic acid (AA) and uric acid (UA) in 0.1-mol L−1 NaCl medium (pH 6.5). Compared to the bare electrode that only displayed a broad and overlapped oxidation peak, the Nafion/MWNT
film-modified electrode not only remarkably enhanced the anodic peak currents of AA and UA but also avoided the overlapping
of the anodic peaks of AA and UA with a 320-mV separation of both peaks. Under the optimized conditions, the peak currents
of AA and UA were proportional to their concentration at the ranges of 8.0 × 10−5 to 6.0 × 10−3 mol L−1 and 6.0 × 10−7 to 8.0 × 10−5 mol L−1, respectively. The proposed method was used for the detection of AA and UA in real samples with satisfactory results. 相似文献
9.
Wei-De Zhang Bin Xu Yu-Xiang Hong Yu-Xiang Yu Jian-Shan Ye Jia-Qi Zhang 《Journal of Solid State Electrochemistry》2010,14(9):1713-1718
In this paper, an electrochemical sensor for sensitive and convenient determination of salicylic acid (SA) was constructed
using well-aligned multiwalled carbon nanotubes as electrode material. Compared to the glassy carbon electrode, the electro-oxidation
of SA significantly enhanced at the multiwalled carbon nanotube (MWCNT) electrode. The MWCNT electrode shows a sensitivity
of 59.25 μA mM−1, a low detection limit of 0.8 × 10−6 M and a good response linear range with SA concentration from 2.0 × 10−6 to 3.0 × 10−3 M. In addition, acetylsalicylic acid was determined indirectly after hydrolysis to SA and acetic acid, which simplified the
detection process. The mechanism of electrochemical oxidation of SA at the MWCNT electrode is also discussed. 相似文献
10.
Juliana Canto Duarte Rita de Cássia Silva Luz Flavio Santos Damos Adriano Bof de Oliveira Lauro Tatsuo Kubota 《Journal of Solid State Electrochemistry》2007,11(5):631-638
The electrocatalytical oxidation of hydrazine at low potential using tetracyanoquinodimethanide adsorbed on silica modified
with titanium oxide was investigated by cyclic voltammetry and amperometry. The modified electrode was prepared modifying
a carbon paste electrode employing lithium tetracyanoquinodimethanide adsorbed onto silica gel modified with titanium oxide.
This electrode showed an excellent catalytic activity and stability for hydrazine oxidation. With this modified electrode,
the oxidation potential of hydrazine was shifted toward less positive value, presenting a peak current much higher than those
observed on a bare GC electrode. The linear response range, sensitivity and detection limit were, respectively, 2 up to 100 μmol
l−1, 0.36 μA l μmol−1, and 0.60 μmol l−1. The repeatability of the modified electrode evaluated in term of relative standard deviation was 4.2% for 10 measurements
of 100 μmol l−1 hydrazine solution. The number of electrons involved in hydrazine oxidation (4), the heterogenous electron transfer rate
constant (1.08 × 103 mol−1 l s−1), and diffusion coefficient (5.9 × 10−6 cm2 s−1) were evaluated with a rotating disk electrode. 相似文献
11.
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
12.
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
13.
Sh. Lü 《Russian Journal of Electrochemistry》2006,42(2):163-166
A glassy-carbon electrode modified with a thin film of multiwall carbon nanotubes is used for the determination of nicotinic
acid (NA). At the electrode, the latter yields a well-defined and very sensitive oxidation peak at 0.21 V (SCE). Investigation
of the electrochemical behavior of NA shows that the electrode significantly enhances the NA oxidation peak current, compared
with the non-modified electrode. Based on this, a very sensitive and simple electrochemical method is proposed for the NA
determination after the optimization of all experimental parameters. The oxidation peak current is proportional to the NA
concentration over the range 2×10−7 to 4×10−5 M, and the detection limit is 8×10−8 M after a 4-min accumulation. The relative standard deviation of 5.4% for the successive determination of 1×10−6 MNA (n=10) indicates excellent reproducibility. The analysis method is successfully demonstrated using tablet samples.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 2, pp. 190–195.
The text was submitted by the author in English. 相似文献
14.
The electrochemical behaviors of metol on an ionic liquid N-butylpyridinium hexafluorophosphate modified carbon paste electrode (IL-CPE) were studied in this paper. The results indicated
that a pair of well-defined quasi-reversible redox peaks of metol appeared with the decrease of overpotential and the increase
of redox peak current, which was the characteristics of electrocatalytic oxidation. The electrocatalytic mechanism was discussed
and the electrochemical parameters were calculated with results of the charge-transfer coefficient (α) as 0.45, the electrode reaction rate constant (k
s) as 4.02 × 10−3 s−1, and the diffusion coefficient (D) as 6.35 × 10−5 cm2/s. Under the optimal conditions, the anodic peak current was linear with the metol concentration in the range of 5.0 × 10−6 ∼ 1.0 × 10−3 mol/L (n = 11, γ = 0.994) and the detection limit was estimated as 2.33 × 10−6 mol/L (3σ). The proposed method was successfully applied to determination of metol content in synthetic samples and photographic solutions. 相似文献
15.
Herein, a sodium montmorillonite-modified carbon paste electrode is described for the electrochemical determination of guanine.
Guanine yields a well-defined and very sensitive oxidation peak at the sodium montmorillonite-modified carbon paste electrode.
Compared with the unmodified carbon paste electrode, the modified electrode facilitates the electron transfer of guanine,
since it notably increases the oxidation peak current and lowers the oxidation overpotential of guanine. Based on this, a
simple sensitive reliable electrochemical method is proposed for the detection of guanine after all the experimental parameters,
such as solution pH value, sodium montmorillonite content in the carbon paste electrode, accumulation potential, and time,
are optimized. Under the optimized conditions, the oxidation peak current of guanine varies linearly with its concentration
in the range 5.0×10−8 to 2.0×10−5 M and the detection limit (signal-to-noise=3) is 2.0×10−8 M after 4-min accumulation. This method is successfully demonstrated with urine samples.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 2, pp. 178–182.
The text was submitted by the authors in English. 相似文献
16.
M. Yousef Elahi H. Heli S. Z. Bathaie M. F. Mousavi 《Journal of Solid State Electrochemistry》2007,11(2):273-282
The electrocatalytic oxidation of glucose was investigated on a nickel-basedchemically modified electrode (Ni(II)-curcumin) prepared by electropolymerization of Ni-curcumin complex (curcumin=1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) in alkaline solution. Reaction kinetic and mechanism were investigated by using cyclic voltammetry (CV) and chronoamperometry (CA) techniques and steady-state polarization measurements. Cyclic voltammetry studies indicated that in the presence of glucose the anodic peak current of surface redox mediator was increased, followed by decrease in the corresponding cathodic current. This indicates that glucose was oxidized at the surface of this modified electrode. The results were explained based on the concept of electrocatalytic reactions that occur in this chemically modified electrode. The diffusion coefficient of glucose and the rate constant of the catalytic oxidation of glucose were found to be 6.7×10−6 cm2 s−1 and 6.5×103 M−1 s−1, respectively. It has shown that by using the Ni-curcumin modified electrode, glucose can be determined with good response and low detection limit. 相似文献
17.
Hadi Beitollahi Mohammad Mazloum Ardakani Hossein Naeimi Bahram Ganjipour 《Journal of Solid State Electrochemistry》2009,13(3):353-363
The preparation and electrochemical characterization of a carbon nanotube paste electrode modified with 2,2′-[1,2-ethanediylbis
(nitriloethylidyne)]-bis-hydroquinone, referred to as EBNBH, was investigated. The EBNBH carbon nanotube paste electrode (EBNBHCNPE)
displayed one pair of reversible peaks at E
pa = 0.18 V and E
pc = 0.115 V vs Ag/AgCl. Half wave potential (E
1/2) and ΔE
p were 0.148 and 0.065 V vs Ag/AgCl, respectively. The electrocatalytic oxidation of ascorbic acid (AA) has been studied on
EBNBHCNPE, using cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques. It has been shown that
the oxidation of AA occurs at a potential where oxidation is not observed at the unmodified carbon paste electrode. The heterogeneous
rate constant for oxidation of AA at the EBNBHCNPE was also determined and found to be about 1.07 × 10−3 cm s−1. The diffusion coefficient of AA was also estimated as 5.66 × 10−6 cm2 s−1 for the experimental conditions, using chronoamperometry. Also, this modified electrode presented the property of electrocatalysing
the oxidation of AA and uric acid (UA) at 0.18 and 0.35 V vs Ag/AgCl, respectively. The separations of anodic peak potentials
of AA and UA reached 0.17 V. Using differential pulse voltammetry, the calibration curves for AA and UA were obtained over
the range of 0.1–800 μM and 20–700 μM, respectively. With good selectivity and sensitivity, the present method provides a
simple method for selective detection of AA and UA in biological samples. 相似文献
18.
The main purpose of this study is to develop an inexpensive, simple, selective and especially sensitive modified carbon paste
electrode (MCPE) for the determination of dopamine (DA) in pharmaceutical and human serum samples. The carbon paste electrode (CPE) has been modified by using [N,N′-bis(2-pyridine carboxamido)-1,2-benzene] nickel(II) complex (Ni(II)bpb) and the electrochemical
behavior of the modified electrode has been studied by cyclic voltammetry. The modified electrode shows an excellent electrocatalytic
effect on the oxidation of DA. Under optimum conditions, calibration plots are found to be linear in the range of 7.0 × 10−7−1.0 × 10−5 M (r
2 = 0.9940) and 1.0 × 10−5−1.0 × 10−4 M (r2 = 0.9945); the detection limit is 6.2 × 10−8 M. The preparation of MCPE is very easy. The electrode can be renewed by simple polishing. The proposed method shows good
sensitivity, reproducibility (RSD ∼ 2.9%), high stability (more than two month) without any considerable change in response
and recovery for the determination of DA. The prepared electrode has been successfully applied to the voltammetric determination
of DA in pharmaceutical and biological samples.
The article is published in the original. 相似文献
19.
Zhao Song Zixia Zhao Xia Qin Jiadong Huang Haibin Shi Baoyan Wu Qiang Chen 《Frontiers of Chemistry in China》2007,2(2):146-150
A novel amperometric choline biosensor has been fabricated with choline oxidase (ChOx) immobilized by the sol-gel method on
the surface of multi-walled carbon nanotubes (MWCNT) modified platinum electrode to improve the sensitivity and the anti-interferential
property of the sensor. By analyzing the electrocatalytic activity of the modified electrode by MWCNT, it was found that MWCNT
could not only improve the current response to H2O2 but also decrease the electrocatalytic potential. The effects of experimental variables such as the buffer solutions, pH
and the amount of loading enzyme were investigated for the optimum analytical performance. This sensor shows sensitive determination
of choline with a linear range from 5.0 × 10−6 to 1.0 × 10−4 mol/L when the operating pH and potential are 7.2 and 0.15 V, respectively. The detection limit of choline was 5.0 × 10−7 mol/L. Selectivity for choline was 9.48 μA·(mmol/L)−1. The biosensor exhibits excellent anti-interferential property and good stability, retaining 85% of its original current
value even after a month. It has been applied to the determination of choline in human serum.
Translated from Chinese Journal of Analytical Chemistry, 2006, 34(7): 910–914 (in Chinese) 相似文献
20.
Huanshun Yin Yunlei Zhou Lin Cui Xianggang Liu Shiyun Ai Lusheng Zhu 《Journal of Solid State Electrochemistry》2011,15(1):167-173
Electrochemical behavior of bisphenol A (BPA) at glassy carbon electrode-modified with layered double hydroxide (LDH) and
anionic surfactant (sodium dodecyl sulfate) is investigated by electrochemical techniques. Compared with the bare electrode
and LDH-modified electrode, the oxidation peak potential of BPA shifted negatively and the peak current increased significantly
due to the enhanced accumulation of BPA via electrostatic interaction with LDH at the hydrophobic electrode surface. Some
determination conditions such as LDH loading, pH, scan rate, accumulation potential, and accumulation time on the oxidation
of BPA were optimized. And some kinetic parameters were investigated. Under the optimized conditions, the oxidation current
was proportional to BPA concentration in the range of 8 × 10−9 to 2.808 × 10−6 M with the detection limit of 2.0 × 10−9 M by amperometry. The fabricated electrode showed good reproducibility, stability, and anti-interference. The proposed method
was successfully applied to determine BPA in water samples, and the results were satisfactory. 相似文献