共查询到20条相似文献,搜索用时 15 毫秒
1.
In this study, a molecularly imprinted electrochemical sensor (MIP/DA) was investigated for selective and sensitive determination of dopamine (DA) by electrochemical polymerization of p-aminothiophenol in the presence of DA on gold electrode. According to electrochemical behaviour of the sensor, gained through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), MIP/DA sensor showed distinctive electron transfer characteristics in comparison to the non-imprinted (NIP/DA) sensor. Besides the MIP/DA sensor showed high selectivity for dopamine through its analyte specific cavities. The sensor had a broad working range of 5.0×10−8–2.0×10−7 M with a limit of detection (LOD) of 1.8×10−8 M and the developed sensor was successfully applied for determination of dopamine in pharmaceutical samples. 相似文献
2.
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
3.
Jahan Bakhsh Raoof Abolfazl Kiani Reza Ojani Roudabeh Valiollahi Sahar Rashid-Nadimi 《Journal of Solid State Electrochemistry》2010,14(7):1171-1176
Gold nanoparticles (GNs) could be efficiently immobilized on binary mixed self-assembled monolayers (SAMs) on a gold surface
composed of 1,6-hexanedithiol and 1-octanethiol (nano-Au/SAMs gold electrode). This GN chemically modified electrode was used
for electrochemical determination of ascorbic acid (AA) and dopamine (DA) in aqueous media. The result showed that the GN-modified
electrode could clearly resolve the oxidation peaks of AA and DA, with a peak-to-peak separation (∆E
p) of 110 mV enabling determination of AA and DA in the presence of each other. The linear analytical curves were obtained
in the ranges of 0.3–1.4 mM for AA and 0.2–1.2 mM for DA concentrations using differential pulse voltammetry. The detection
limits (3σ) were 9.0 × 10−5 M for AA and 9.0 × 10−5 M for DA. 相似文献
4.
Determination of chromium(VI) and total chromium in water by in-electrode coulometric titration in a porous glassy carbon electrode 总被引:1,自引:0,他引:1
Chromium(VI) is determined through its direct electrochemical reduction in the bulk of a porous glassy carbon electrode. An
electrode filled with the acidified sample and Cr(VI) is reduced by means of a constant current whereas the potential of the
electrode is monitored. The limits of detection and quantification were found to be 1.9 and 6.0 μg · L−1, resp. The linear range, repeatability and reproducibility were found to be 5–500 μg · L−1, 1.2, and 1.8%, resp. The influence of Fe(III), Ca(II), Mg(II), sulphates, nitrates, humic acids and surfactants was investigated.
Total chromium was measured after chemical oxidation of Cr(III) to chromate by permanganate. The method was applied to analyses
of water samples. 相似文献
5.
Leveriza F. Arenas Benilda S. Ebarvia Fortunato B. Sevilla III 《Analytical and bioanalytical chemistry》2010,397(7):3155-3158
A piezoelectric quartz crystal (PQC) sensor based on a molecularly imprinted polymer (MIP) has been developed for enantioselective
and quantitative analysis of d-(+)-methamphetamine (d(+)-MA). The sensor was produced by bulk polymerization and the resulting MIP was then coated on the
gold electrode of an AT-cut quartz crystal. Conditions such as volume of polymer coating, curing time, type of PQC, baseline
solvent, pH, and buffer type were found to affect the sensor response and were therefore optimized. The PQC-MIP gave a stable
response to different concentrations of d(+)-MA standard solutions (response time = 10 to 100 s) with good repeatability (RSD = 0.03
to 3.09%; n = 3), good reproducibility (RSD = 3.55%; n = 5), and good reversibility (RSD = 0.36%; n = 3). The linear range of the sensor covered five orders of magnitude of analyte concentration, ranging from 10−5 to 10−1 μg mL−1, and the limit of detection was calculated as 11.9 pg d(+)-MA mL−1
. The sensor had a highly enantioselective response to d(+)-MA compared with its response to l(−)-MA, racemic MA, and phentermine.
The developed sensor was validated by applying it to human urine samples from drug-free individuals spiked with standard d(+)-MA
and from a confirmed MA user. Use of the standard addition method (SAM) and samples spiked with d(+)-MA at levels ranging
from 1 × 10−3 to 1 × 10−2 μg mL−1 showed recovery was good (95.3 to 110.9%). 相似文献
6.
Lei Zhang 《Mikrochimica acta》2008,161(1-2):191-200
A covalently modified glassy carbon electrode with cysteine has been fabricated via an electrochemical oxidation procedure
and was applied to induce the electrochemical differentiation between dopamine (DA) and ascorbic acid (AA). Based on the electrostatic
interactions between the negatively charged groups on the electrode surface and DA and AA, the modified electrode enhanced
the oxidation of DA, reducing the overpotential by 180 mV, and hindered the oxidation of AA, shifting the oxidation potential
positively by 170 mV. The peak current for DA at the modified electrode was greatly enhanced and that for AA was significantly
decreased, which allows the determination of DA in the presence of AA. The differential pulse peak current was linearly dependent
on DA concentration over the range of 5 × 10−6–2 × 10−4 mol L−1. The detection limit was 1.8 × 10−6 mol L−1. The selectivity and sensitivity for dopamine is due to charge discrimination and analyte accumulation. The modified electrode
has been applied to the determination of DA in the presence of AA.
Correspondence: L. Zhang, Department of Chemistry, College of Life and Environmental Science, Shanghai Normal University,
Guilin Rd 100, Shanghai 200234, P.R. China 相似文献
7.
A poly(caffeic acid) thin film was deposited on the surface of a glassy carbon electrode by potentiostatic technique in an
aqueous solution containing caffeic acid. The poly(caffeic acid)-modified electrode was used for the determination of ascorbic
acid (AA), dopamine (DA), and their mixture by cyclic voltammetry. This modified electrode exhibited a potent and persistent
electron-mediating behavior followed by well-separated oxidation peaks toward AA and DA at a scan rate of 10 mV s−1 with a potential difference of 135 mV, which was large enough to determine AA and DA individually and simultaneously. The
catalytic peak current obtained was linearly dependent on the AA and DA concentrations in the range of 2.0 × 10−5−1.2 × 10−3 and 1.0 × 10−6−4.0 × 10−5 mol L−1 in 0.15 mol L−1 phosphate buffer (pH 6.64). The detection limits for AA and DA were 9.0 × 10−6 and 4.0 × 10−7 mol L−1, respectively. The modified electrode shows good sensitivity, selectivity, and stability and has been applied to the determination
of DA and AA in real samples with satisfactory results. 相似文献
8.
Yufang Hu Zhaohui Zhang Huabin Zhang Lijuan Luo Shouzhuo Yao 《Journal of Solid State Electrochemistry》2012,16(3):857-867
A sensitive molecularly imprinted electrochemical sensor was developed for selective detection of streptomycin by combination
of mercaptoacetic acid-modified PbS nanoparticles with Au-coated Fe3O4 magnetic nanoparticles dispersed multi-walled carbon nanotubes doped chitosan film. The imprinted sensor was fabricated onto
the Au electrode via stepwise modification of nanocomposites and an electrodeposited thin film of molecularly imprinted polymers
via sol–gel technology. The morphologies and electrochemical behaviors of the imprinted sensor were characterized by scanning
electron microscope, cyclic voltammetry, and differential pulse voltammetry, respectively. The prepared sensor showed very
high recognition ability and selectivity for streptomycin. Under optimal conditions, the imprinted sensor displayed good electrocatalytic
activity to the redox of streptomycin. And the differential voltammetric anodic peak current was linear to the logarithm of
streptomycin concentration in the range from 1.0 × 10−6 to 1.0 × 10−3 mol L−1, and the detection limit obtained was 1.5 × 10−9 mol L−1. This proposed imprinted sensor was used successfully for streptomycin determination in different injection solution samples. 相似文献
9.
A multi-walled carbon nanotube paste electrode (MWCPE) is prepared as an electrochemical sensor with high sensitivity and
selectivity in responding to isoniazid. The electrochemical oxidation of isoniazid is investigated in buffered solution by
cyclic and differential pulse voltammetry. The electrode is shown to be very effective for the detection of isoniazid in the
presence of other biological reductant compounds. The electrochemical oxidation of cysteine, due to the high overvoltage,
is completely stopped at the surface of MWCPE. The electrode exhibits a very good resolution between the voltammetric peak
of isoniazid and the peaks of ascorbic acid (AA) and dopamine (DA). A resolution of more than 450 mV between the anodic peak
potentials makes the MWCPE suitable for simultaneous detection of isoniazid in the presence of AA or DA in clinical and pharmaceutical
preparations. Differential pulse voltammetry (DPV) is applied as a sensitive method for the determination of isoniazid. The
linear range in these determinations is 1 × 10−6–1 × 10−3 M for isoniazid and the detection limit is 5 × 10−7 M. The electrode was applied to the simultaneous determinations in isoniazid and AA mixtures and also, isoniazid and DA mixture
over a wide concentration range. The slope variation for the calibration curves of isoniazid (RSD) was less than 4.5% (based
on ten measurements over a period of three months). 相似文献
10.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
11.
M. Mazloum Ardakani A. Talebi H. Naeimi M. Nejati Barzoky N. Taghavinia 《Journal of Solid State Electrochemistry》2009,13(9):1433-1440
A carbon paste electrode, modified with 2, 2′-[1,7-hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone and TiO2 nanoparticles, was used for the simultaneous determination of dopamine (DA), uric acid (UA), and l-cysteine. The study was carried out by using cyclic voltammetry, chronoamperometry, and square wave voltammetry (SWV) techniques.
Some kinetic parameters such as the electron transfer coefficient (α) and heterogeneous rate constant (ks) were also determined for the DA oxidation. A dynamic range of 8.0–1400 μM, with the detection limit of 8.4 × 10−7 M for DA, was obtained using SWV (pH = 7.0). The prepared electrode was successfully applied for the determination of DA,
UA, and l-cysteine in real samples. 相似文献
12.
Gema Paniagua González Pilar Fernández Hernando Jesús Senén Durand Alegría 《Analytical and bioanalytical chemistry》2009,394(4):963-970
This work reports a comparative study of two automated flow-through fluorosensors for the determination of digoxin in serum
samples: an immunosensor with an anti-digoxin polyclonal antibody as the reactive phase permanently immobilised on controlled-pore
glass and a sensor with a selective reaction system based on a methacrylic molecularly imprinted polymer (MIP) synthesised
by bulk polymerisation. The variables affecting the sensitivity and dynamic range of the sensors (e.g. the carrier and elution
solutions, flow rates, pH and reagent concentrations) were optimized, and the binding characteristics of their reactive phases
were compared in a competitive fluorescent assay. Digoxin was reproducibly determined by both sensors at the milligram per
litre level (detection limit = 1.20 × 10−3 mg L−1 and RSD = 4–7% for the immunosensor; detection limit = 1.7 × 10−5 mg L−1 and RSD = 1–2% for the MIP sensor). No cross-reactivity with digoxin-related compounds was seen for either sensor at a digoxin/interferent
ratio of 1:100. The lifetime of the immunosensor was about 50 immunoassays; its shelf life, when unused, is about 3 months.
The lifetime of the MIP sensor was over 18 months. Both sensors were used to determine the digoxin concentration of human
serum samples with satisfactory results. 相似文献
13.
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
14.
Jianping Li Xiongzhi Wu Yong Yu Shangwang Le 《Journal of Solid State Electrochemistry》2009,13(12):1811-1818
Gold electrode with self-assembled D,L-cysteine grafted β-cyclodextrin sulfonic acid (Cys-β-CD∼SO3) layer was fabricated and used to investigate the electrochemical behavior of dopamine. The experimental results indicated
that the self-assembled Cys-β-CD∼SO3 layer modified gold electrode has selective electrochemical response to dopamine with high sensitivity and excellent tolerance
of ascorbic acid, which is the most common accompanying component in biological samples. Dopamine could be accurately determined
in the concentration range of 1–200 μM in the presence of ascorbic acid of 5 mM. The relative standard deviation of 1.9% (n = 5) was achieved at a dopamine concentration of 5 × 10−5 M. The proposed sensor was successfully applied to the determination of dopamine in human blood serum samples. 相似文献
15.
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
16.
A glassy carbon electrode was modified with electropolymerized film of diphenylamine sulfonic acid (DPASA). Electropolymerization was performed by cyclic voltammetry in 0.1 M KCl solution. The modified electrode showed an excellent
electrocatalytic effect towards oxidation of dopamine (DA) and ascorbic acid (AA). Electrostatic interaction between the negatively charged poly(DPASA) film and either cationic DA species or anionic AA
species favorably contributed to the redox response of DA and AA. Anodic peaks of DA and AA in their mixture were well separated
by ca 168 and −11.8 mV. The proposed modified electrode was utilized for selective determination of dopamine in the concentration
range of 5.0 × 10t7–2.0 × 10−5 M in the presence of high concentration of ascorbic acid. Detection limit was 6.5 × 10−9 M. 相似文献
17.
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
18.
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
19.
A poly(L-methionine) modified electrode, fabricated by electrochemical immobilization of the L-methionine on a glassy carbon
electrode, was used for simultaneous determination of dopamine and epinephrine through cyclic voltammetry. The electrochemical
properties of dopamine and epinephrine have been investigated. This sensor gave two separated cathodic peaks at −0.282 and
0.112 V for EP and DA, respectively. A linear response was obtained in the range of 5.0 × 10−7 to 1.0 × 10−4 mol l−1 for epinephrine, and 1.0 × 10−6 to 5.0 × 10−4 mol l−1 for dopamine. The detection limits were 3.6 × 10−7 mol l−1 and 4.2 × 10−7 mol l−1 for epinephrine and dopamine, respectively. This method was successfully applied for simultaneous determination of dopamine
and epinephrine in human urines.
The text was submitted by the authors in English. 相似文献
20.
Reza Ansari Ali Fallah Delavar Alireza Aliakbar Ali Mohammad-khah 《Journal of Solid State Electrochemistry》2012,16(3):869-875
A pencil graphite electrode coated by copper (II)–carmoisine dye complex in polyaniline (emeraldine base form) matrix (termed
as PGE/PA/Cu-Car) was prepared and used as copper ion-selective electrode. The introduced electrode was found to have high
selectivity toward copper ion (II) and exhibited wide working concentration range, low response time, and good shelf life.
The sensor electrode showed a linear Nernstian response over the range of 5.0 × 10−6 to 1.0 × 10−1 M with a slope of 29.7 ± 1 mV per decade change in concentration. A detection limit of 2.0 × 10−6 M was obtained. The optimum pH working range of the electrode was found to be 4.0–7.0. 相似文献