共查询到20条相似文献,搜索用时 31 毫秒
1.
Conducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction
of a solid-contact Pb2+-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer
and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry
and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron
transport process. The new Pb2+-selective polymeric membrane electrode, based on PPy-Nafion film as solid contact, shows stable Nernstian characteristics
in Pb(NO3)2 solution within the concentration range of 1.0 × 10−7–1.0 × 10−3 M, and the detection limit is 4.3 × 10−8 M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry
and potentiometric water layer test, respectively. The results show that the solid-contact Pb2+-selective electrode, based on PPy-Nafion film as ion-to-electron transducer, can effectively overcome the potential drift
and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane. 相似文献
2.
Raúl A. Sánchez-Moreno M. Jesús Gismera M. Teresa Sevilla Jesús R. Procopio 《Analytical and bioanalytical chemistry》2010,397(1):331-338
A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis.
The carbon screen-printed electrode was modified with a graphite–epoxy composite. The optimal graphite–epoxy matrix contains
37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal
analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed
sensor exhibits a response time of 20 ± 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour
using 0.1 M NaNO3 solution at pH 3 as the carrier, a flow rate of 2.5 mL·min−1, and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI)
ions and optimal detection limits in both static mode (2.1 × 10−7 M) and online analysis (9.4 × 10−7 M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river
waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful
results in leachates from municipal solid waste landfills. 相似文献
3.
Chun-Ze Lai Marti M. Joyer Melissa A. Fierke Nicholas D. Petkovich Andreas Stein Philippe Bühlmann 《Journal of Solid State Electrochemistry》2009,13(1):123-128
Solid-contact ion-selective electrodes (SC-ISEs) can exhibit very low detection limits and, in contrast to conventional ISEs,
do not require an optimization of the inner filling solution. This work shows that subnanomolar detection limits can also
be achieved with SC-ISEs with three-dimensionally ordered macroporous (3DOM) carbon contacts, which have been shown recently
to exhibit excellent long-term stabilities and good resistance to the interferences from oxygen and light. The detection limit
of 3DOM carbon-contacted electrodes with plasticized poly-(vinyl chloride) as membrane matrix can be improved with a high
polymer content of the sensing membrane, a large ratio of ionophore and ionic sites, and conditioning with a low concentration
of analyte ions. This permits detection limits as low as 1.6 × 10−7 M for K+ and 4.0 × 10−11 M for Ag+. 相似文献
4.
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
5.
This paper reports the construction and evaluation of a dopamine sensitive electrode and its usefulness for the determination
of this compound by direct potentiometry in pharmaceutical preparations. The electrode comprised a carboxylated poly(vinyl
chloride) membrane based on β-cyclodextrine dissolved in 2-fluoro-2-nitrodiphenyl ether and using tetrakis(p-chlorophenyl)
borate as a fixed anionic site. For comparison purposes membranes with similar composition but including normal high molecular
weight PVC were also prepared.
The electrodes including carboxylated poly(vinyl chloride) presented linear response within the concentration range of 5×10−5 and 10−1 mol dm−3 of dopamine with a slope of about 59 mV decade−1 of activity, in the pH range of 2 to 7.5 units. The response time was less than 15 seconds. Selectivity coefficients for
different interferents including sodium, potassium, ammonium, lithium, epinephrine and norepinephrine were evaluated using
the separated solution method and no significant interferences were observed. The electrode displays useful analytical characteristics
for the direct determination of dopamine in pharmaceutical preparations. Results with an average recovery of 98.6±0.3% were
obtained.
Received May 28, 1998. Revision March 2, 1999. 相似文献
6.
Oxytetracycline hydrochloride-selective electrodes of both the coated wire and the conventional polymer membrane types based
on oxytetracyclinium phosphotungstate and phosphomolybdate have been prepared. A Nernstian response is shown by these electrodes
within 1.0×10−6–1.0×10−2 M concentration ranges depending on the type of electrode. The response is unaffected by the change of pH over the range
4–11. The standard electrode potentials, E°, were determined at different temperatures and used to calculate the isothermal
temperature coefficients of the electrodes. The electrodes show good selectivity to oxytetracycline hydrochloride with respect
to many inorganic cations, sugars and amino-acids. Oxytetracycline hydrochloride is determined successfully in pure solutions
and in pharmaceutical preparations using calibration by standard addition and potentiometric titration. A regeneration process
for the exhausted electrodes has been developed.
Received February 2, 2000. Revision April 7, 2000. 相似文献
7.
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
8.
Arvand M Pourhabib A Shemshadi R Giahi M 《Analytical and bioanalytical chemistry》2007,387(3):1033-1039
Liquid polymer membrane electrodes based on nickel and manganese phthalocyanines were examined for use as anion-selective
electrodes. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes,
which were directly coated onto the surfaces of graphite electrodes. The resulting electrodes demonstrate near-Nernstian responses
over a wide linear range of perchlorate anion (5 × 10−7 to 1 × 10−1 M). The electrodes have a fast response time, submicromolar detection limits (5 × 10−7 M perchlorate), and could be used over a wide pH range of 3.5–10. The influences of lipophilic cationic and anionic additives
on the response properties of the electrodes were investigated. The proposed sensors revealed high selectivity for perchlorate
over a number of common inorganic and organic anions. The highest selectivity was observed for the electrode based on manganese
phthalocyanine in the presence of the lipophilic anionic additive sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. Application
of the electrodes to determine perchlorate in tap water and human urine is also reported.
相似文献
9.
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
10.
Ahmad Soleymanpour Bahram Garaili S. Masoud Nabavizadeh 《Monatshefte für Chemie / Chemical Monthly》2008,139(12):1439-1445
Three platinum(II) complexes were synthesized and studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with
one of these complexes showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4
− ions over a wide concentration range from 1.5 × 10−6 to 2.7 × 10−1 M for PME and 5.0 × 10−7 to 1.9 × 10−1 M for CGCE with low detection limits (9.0 × 10−7 M for PME and 4.0 × 10−7 M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly,
good selectivity toward ClO4
− relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.0–9.0. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine
samples.
Correspondence: Ahmad Soleymanpour, Department of Chemistry, Damghan Basic Science University, Damghan, Iran. 相似文献
11.
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
12.
M. H. Pournaghi-Azar H. Dastangoo M. Ziaei 《Journal of Solid State Electrochemistry》2007,11(9):1221-1227
The electrocatalytic activity of a Prussian blue (PB) film on the aluminum electrode by taking advantage of the metallic palladium
characteristic as an electron-transfer bridge (PB/Pd–Al) for electrooxidation of 2-methyl-3-hydroxy-4,5-bis (hydroxyl–methyl)
pyridine (pyridoxine) is described. The catalytic activity of PB was explored in terms of FeIII [FeIII (CN)6]/FeIII [FeII (CN)6]1− system. The best mediated oxidation of pyridoxine (PN) on the PB/Pd–Al-modified electrode was achieved in 0.5 M KNO3 + 0.2 M potassium acetate of pH 6 at scan rate of 20 mV s−1. The mechanism and kinetics of the catalytic oxidation reaction of PN were monitored by cyclic voltammetry and chronoamperometry.
The results were explained using the theory of electrocatalytic reactions at chemically modified electrodes. The charge transfer-rate
limiting reaction step is found to be a one-electron abstraction, whereas a two-electron charge transfer reaction is the overall
oxidation reaction of PN by forming pyridoxal. The value of α, k, and D are 0.5, 1.2 × 102 M−1 s−1, and 1.4 × 10−5 cm2 s−1, respectively. Further examination of the modified electrodes shows that the modifying layers (PB) on the Pd–Al substrate
have reproducible behavior and a high level of stability after posing it in the electrolyte or Pyridoxine solutions for a
long time. 相似文献
13.
By combining the layer-by-layer (LBL) self-assembly technique with the electrochemical polymerization method, multilayer Ni(II)-polyluminol
films were modified on the surface of a vaseline-impregnated graphite electrode. It was found that, compared with an electrode
modified by direct electrochemical polymerization, this modified electrode offered a suitable ECL reaction micro-environment
created by the special multilayer films, which was beneficial to the ephedrine hydrochloride enhancing effect for luminol
ECL intensity. The ECL enhancing effect of ephedrine hydrochloride on the electro-oxidation luminol was improved on this modified
electrode. Based on this finding, a new sensitive ECL method was developed for ephedrine hydrochloride determination under
the optimal conditions. At the same time, a new idea is proposed for improving the analytical performance of the luminol ECL
system by modifying the ECL reaction micro-environment with the layer-by-layer self- assembly method. Under the optimum experimental
conditions, the ephedrine hydrochloride concentration in the range of 2.0 × 10−8–7.0 × 10−6 mol L−1 was proportional to the enhanced ECL signal, and it offered an 8.0 × 10−9 mol L−1 detection limit for ephedrine hydrochloride. 相似文献
14.
Mohammad Ali Kamyabi Z. Asgari H. Hosseini Monfared 《Journal of Solid State Electrochemistry》2010,14(9):1547-1553
A carbon past electrode modified with [Mn(H2O)(N3)(NO3)(pyterpy)],
( \textpyterpy = 4¢- ( 4 - \textpyridyl ) - 2,2¢:\text6¢,\text2¢¢- \textterpyridine ) \left( {{\text{pyterpy}} = 4\prime - \left( {4 - {\text{pyridyl}}} \right) - 2,2\prime:{\text{6}}\prime,{\text{2}}\prime\prime - {\text{terpyridine}}} \right) complex have been applied to the electrocatalytic oxidation of nitrite which reduced the overpotential by about 120 mV with
obviously increasing the current response. Relative standard deviations for nitrite determination was less than 2.0%, and
nitrite can be determined in the ranges of 5.00 × 10−6 to 1.55 × 10−2 mol L−1, with a detection limit of 8 × 10−7 mol L−1. The treatment of the voltammetric data showed that it is a pure diffusion-controlled reaction, which involves one electron
in the rate-determining step. The rate constant k′, transfer coefficient α for the catalytic reaction, and diffusion coefficient of nitrite in the solution, D, were found to be 1.4 × 10−2, 0.56× 10−6, and 7.99 × 10−6 cm2 s−1, respectively. The mechanism for the interaction of nitrite with the Mn(II) complex modified carbon past electrode is proposed.
This work provides a simple and easy approach to detection of nitrite ion. The modified electrode indicated reproducible behavior,
anti-fouling properties, and stability during electrochemical experiments, making it particularly suitable for the analytical
purposes. 相似文献
15.
Letao Wang Yan Zhang Yongling Du Daban Lu Yuzhen Zhang Chunming Wang 《Journal of Solid State Electrochemistry》2012,16(4):1323-1331
Simultaneous determination of catechol (CC) and hydroquinone (HQ) were investigated by voltammetry based on glassy carbon
electrode (GCE) modified by poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G). The modified
electrode showed excellent sensitivity and selectivity properties for the two dihydroxybenzene isomers. In 0.1 mol/L phosphate
buffer solution (PBS, pH 7.0), the oxidation peak potential difference between CC and HQ was 108 mV, and the peaks on the
PDDA-G/GCE were three times as high as the ones on graphene-modified glass carbon electrode. Under optimized conditions, the
PDDA-G/GCE showed wide linear behaviors in the range of 1 × 10−6−4 × 10−4 mol/L for CC and 1 × 10−6−5 × 10−4 mol/L for HQ, with the detection limits 2.0 × 10−7 mol/L for CC and 2.5 × 10−7 mol/L for HQ (S/N = 3) in mixture, respectively. Some kinetic parameters, such as the electron transfer number (n), charge transfer coefficient (α), and the apparent heterogeneous electron transfer rate constant (k
s), were calculated. The proposed method was applied to simultaneous determine CC and HQ in real water samples of Yellow River
with satisfactory results. 相似文献
16.
Fosamprenavir is a pro-drug of the antiretroviral protease inhibitor amprenavir and is oxidizable at solid electrodes. The
anodic oxidation behavior of fosamprenavir was investigated using cyclic and linear sweep voltammetry at boron-doped diamond
and glassy carbon electrodes. In cyclic voltammetry, depending on pH values, fosamprenavir showed one sharp irreversible oxidation
peak or wave depending on the working electrode. The mechanism of the oxidation process was discussed. The voltammetric study
of some model compounds allowed elucidation of the possible oxidation mechanism of fosamprenavir. The aim of this study was
to determine fosamprenavir levels in pharmaceutical formulations and biological samples by means of electrochemical methods.
Using the sharp oxidation response, two voltammetric methods were described for the determination of fosamprenavir by differential
pulse and square-wave voltammetry at the boron-doped diamond and glassy carbon electrodes. These two voltammetric techniques
are 0.1 M H2SO4 and phosphate buffer at pH 2.0 which allow quantitation over a 4 × 10−6 to 8 × 10−5 M range using boron-doped diamond and a 1 × 10−5 to 1 × 10−4 M range using glassy carbon electrodes, respectively, in supporting electrolyte. All necessary validation parameters were
investigated and calculated. These methods were successfully applied for the analysis of fosamprenavir pharmaceutical dosage
forms, human serum and urine samples. The standard addition method was used in biological media using boron-doped diamond
electrode. No electroactive interferences from the tablet excipients or endogenous substances from biological material were
found. The results were statistically compared with those obtained through an established HPLC-UV technique; no significant
differences were found between the voltammetric and HPLC methods. 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.
Binding of a cationic surfactant ion, dodecylpyridinium ion, to poly(acrylic acids) of low charge densities was examined
by potentiometry using surfactant-selective electrodes in the solutions, where the pH was kept constant by employing a pH
buffering system. The binding of the surfactant counterions was thus able to be studied at a constant pH during the binding
process. The binding took place in two steps, the first cooperative binding step and the second gradual binding step. The
critical association concentration decreased as the pH increased, indicating the predominant role of the electric interaction
in the binding. The binding isotherms obtained at different but constant pH values were analyzed by the matrix method, taking
into account the nearest-neighbor interactions among three different kinds of sites on the polymer: ionized, protonated, and
surfactant-bound. The theoretical analysis could describe only the first step but could not explain the second step. A relatively
large cooperativity parameter, u, was found for the first step and it can be between 3 × 103 and 1 × 104. When the ionic strength was decreased tenfold, the cooperativity of the binding decreased (u∼1 × 103). The binding constants of the isolated site were 5.5–6.0 × 104 kg mol−1 and slightly increased to 6.5 × 104 kg mol−1 as the ionic strength decreased. The deviation of the second step from the theoretical analysis was supposed to arise from
a change of proton dissociation constant in the nonpolar space formed by the bound surfactants.
Received: 29 November 2000/Accepted: 24 January 2001 相似文献
19.
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
20.
Construction of a Triphenyltetrazolium Liquid Membrane Ion Selective Electrode and its Analytical Application to the Assay of Vitamin C 总被引:2,自引:0,他引:2
Panayotis G. Veltsistas Theodosios I. Sikalos Mamas I. Prodromidis Christos D. Papadimitriou Miltiades I. Karayannis 《Mikrochimica acta》2000,135(1-2):113-117
The construction of a liquid triphenyltetrazolium cation (TT+) ion-selective electrode (ISE) based on [TT+]3[P(W3O10)4] salt dissolved in 2-nitrotoluene is described. The liquid membrane electrode exhibits a rapid and almost Nernstian response
to triphenyltetrazolium cations in the concentration range from 2×10−4 to 1×10−2 mol l−1. The Nernstian slope is 56–58 mV decade−1 which remains constant for at least two months. The response is virtually unaffected by pH changes in the range 3–12. Major
interferents are periodate and malate. Deviation from linearity is also observed in the presence of bromide, iodide and thiocyanate,
due to their precipitation with triphenyltetrazolium cations. Analytical applications such as direct potentiometry for the
determination of TT+ in aqueous solutions and indirect potentiometry for the assay of ascorbic acid (vitamin C) in pharmaceutical preparations
are described. Ascorbic acid in the range of 150–500 mg l−1, under specified experimental conditions, can be determined with mean relative error of 1.9%.
Received February 25, 2000. Revision April 4, 2000. 相似文献