共查询到20条相似文献,搜索用时 73 毫秒
1.
Shenghui Zhang 《Russian Journal of Electrochemistry》2011,47(11):1257-1261
A mesoporous TiO2 (meso-TiO2) was synthesized, and used to prepare modified carbon paste electrode (CPE). The electrochemical sensing properties were
characterized using K3[Fe(CN)6], showing that meso-TiO2 modified CPE possesses larger surface area and higher electron transfer rate. The electrochemical behavior of p-cresol was investigated. At the meso-TiO2 modified CPE, the oxidation peak current of p-cresol remarkably increases, and the oxidation peak potential shifts negatively, suggesting that meso- TiO2 exhibits highly efficient catalytic activity to the oxidation of p-cresol. Based on this, a sensitive, rapid and convenient electrochemical method was developed for the detection of p-cresol. The linear range is from 1.5 × 10−7 and 2.0 × 10−5 mol l−1, and the limit of detection is as low as 8.0 × 10−8 mol l−1. Finally, the new method was successfully used to determine p-cresol in water samples. 相似文献
2.
An amperometric sensor for the determination of indole-3-acetic acid (IAA) based on the CeCl3-DHP film modified gold electrode was developed. CeCl3 was dissolved into water in the presence of dihexadecyl hydrogen phosphate (DHP). The IAA sensor was prepared via evaporating
solvent of the CeCl3-DHP dispersion on the gold electrode surface. The amperometric response of IAA on the CeCl3-DHP film modified gold electrode was investigated. The experimental results indicate that the passivation of the electrode
due to the adsorption of the oxidation product of IAA decreases significantly at the CeCl3-DHP film modified gold electrode, in contrast to that at the bare and the DHP modified gold electrode. The experimental parameters
were optimized and an electrochemical method for the determination of IAA was established. The oxidation peak current is linearly
with the concentration of IAA from 1 × 10−7 to 2 × 10−5 mol l−1 and the detection limit is 3 × 10−8 mol l−1. The relative standard deviation of eight measurements is 3.2% for 5 × 10−7 mol l−1 IAA. The IAA in plant leaves were extracted and determined by the IAA sensor. 相似文献
3.
Jinyi Chen Guangzhong Yang Wanyi Li Jiashou Sun 《Russian Journal of Electrochemistry》2009,45(8):908-912
The virgin activated carbon (AC) was oxidized by 30% H2O2 under the ultrasonic condition for 6 h (denoted as AC-6). The electrochemical response of Pb2+ at the AC-6 modified paste electrode was investigated, suggesting that AC-6 shows much higher accumulation efficiency to
trace levels of Pb2+. Based on this, a sensitive and convenient electrochemical method was developed for the determination of Pb2+ utilizing the excellent properties of AC-6. In pH 3.6 HAc-NaAc buffer, Pb2+ was easily accumulate at the surface of AC-6 modified paste electrode, then reduced to Pb at −1.20 V. During the following
anodic sweep, the reduced Pb was oxidized and resulted in an oxidation stripping peak at −0.58 V. The stripping peak current
is proportional to the concentration of Pb2+ over the range from the 8.0 × 10−9 to 2.0 × 10−6 mol l−1, and the limit of detection is as low as 2.0 × 10−9 mol l−1. Finally, this newly-developed method was successfully employed to determine Pb2+ in water samples. 相似文献
4.
A mesoporous SiO2-modified carbon paste electrode for the determination of uric acid is described. Owing to the regular and specific mesoporous
channels, numerous active sites and a large surface area, the mesoporous SiO2-modified electrode greatly increases the oxidation peak current of uric acid. Based on this, a highly sensitive, rapid and
convenient electrochemical method was developed for the determination of uric acid after optimizing the experimental parameters
(supporting electrolyte, content of mesoporous SiO2, accumulation potential and time). The linear range is from 2.5 × 10−7 to 2.0 × 10−5 mol L−1, and the limit of detection is estimated to be 8.0 × 10−8 mol L−1. The relative standard deviation for 10 mesoporous SiO2-modified electrodes is 5.8%. The method was used to determine uric acid in human serum samples.
Correspondence: Kangbing Wu, Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074, P.R. China 相似文献
5.
Anderson M. Campos Paulo A. Raymundo-Pereira Fernando H. Cincotto Thiago C. Canevari Sergio A. S. Machado 《Journal of Solid State Electrochemistry》2016,20(9):2503-2507
In this work, we described an electrochemical sensor using a nanocomposite based on graphene oxide (GO), silver nanoparticles (AgNP), and disordered mesoporous silica (SiO2), which was used for the determination of bisphenol A in water samples. Initially, the hybrid material SiO2/GO was synthesized via sol-gel process, subsequently decorated with AgNP with an approximate 20 nm particle size prepared directly on the surface of the SiO2/GO using N, N-dimethylformamide (DMF) as an agent reducer. A glassy carbon electrode was modified with SiO2/GO/AgNP and used in developing a sensitive electrochemical sensor for the determination of bisphenol A in phosphate buffer 0.1 mol L?1 (pH 7.0). The detection limit was 45.2 nmol L?1 with a linear response range between 1.0 × 10?7 and 2.6 × 10?6 mol L?1 and a sensitivity of 1.27 × 10?7 A mol?1 L. Finally, the optimized electrochemical sensor was used for the quantitation of endocrine interfering in natural waters. 相似文献
6.
A novel amperometric sensor for uric acid based on ordered mesoporous carbon modified pyrolytic graphite electrode was developed.
Uric acid oxidation was easily catalyzed by this electrode in a phosphate buffer solution at pH 7.0, with an anodic potential
decrease about 140 mV compared to bare pyrolytic graphite electrode. The uric acid level was determined by the amperometric
method, at a constant potential of 0.31 mV, the catalytic current of uric acid vs. its concentration showed a good linearity
in the range of 1.0 × 10−6−1.0 × 10−4 mol L−1, with a correlation coefficient of 0.999. The detection limit was 4.0 × 10−7 mol L−1. The proposed method could be effectively used for uric acid amperometric sensing in human urine. 相似文献
7.
《Electroanalysis》2017,29(3):835-842
A novel electrochemically activated doped Ta2O5 particles modified carbon paste electrode (EA‐Ta2O5‐CPE) was prepared and applied for selective and sensitive determination of chrysin. X‐ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) techniques and cyclic voltammetry (CV) were used to characterize the Ta2O5 particles and investigate the electrochemical response of the sensor. Compared with bare CPE, the doped Ta2O5 modified electrode got much more porous by electrochemical treatment and exhibited larger effective surface area, more reactive site and excellent electrochemical catalytic activity toward the oxidation of chrysin. Under optimum conditions by LSV, the oxidation peak currents responded to chrysin linearly over a concentration range from 5.0×10−8 to 7.0×10−6 mol L−1 with a detection limit of 2.0×10−8 mol L−1 (5.08 ng mL−1). The fabricated sensor showed anti‐interference ability against the biological common interferents (i.e. baicalein, baicalin) and provided to be reliable for the determination of chrysin in Chinese medicinal herb Oroxylum indicum and chrysin capsules samples with satisfactory results. 相似文献
8.
CeO2 nanoparticles approximately 12 nm in size were synthesized and subsequently characterized by XRD, TEM and UV-vis spectroscopy.
Then, a gold electrode modified with CeO2 nanoparticles was constructed and characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).
The modified electrode demonstrated strong catalytic effects with high stability towards electrochemical oxidation of rutin.
The anodic peak currents (measured by differential pulse voltammetry) increased linearly with the concentration of rutin in
the range of 5.0 × 10−7–5.0 × 10−4 mol · L−1. The detection limit (S/N = 3) was 2.0 × 10−7 mol · L−1. The relative standard deviation (RSD) of 8 successive scans was 3.7% for 5.0 × 10−6 mol · L−1 rutin. The method showed excellent sensitivity and stability, and the determination of rutin in tablets was satisfactory. 相似文献
9.
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
10.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
11.
D. M. Ortega-Sotelo J. G. Gonzalez-Rodriguez M. A. Neri-Flores M. Casales L. Martinez A. Martinez-Villafañe 《Journal of Solid State Electrochemistry》2011,15(9):1997-2004
The corrosion inhibition of X-70 pipeline steel in saltwater saturated with CO2 at 50 °C with carboxyamido imidazoline has been evaluated by using electrochemical techniques. Techniques included polarization
curves, linear polarization resistance, electrochemical impedance, and electrochemical noise measurements. Inhibitor concentrations
were 0, 1.6 × 10−5, 3.32 × 10−5, 8.1 × 10−5, 1.6 × 10−4, and 3.32 × 10−4 mol l−1. All techniques showed that the best corrosion inhibition was obtained by adding 8.1 × 10−5 mol l−1 of carboxyamido imidazoline. For inhibitor concentrations higher than 8.1 × 10−5 mol l−1 a desorption process occurs, and an explanation has been given for this phenomenon. 相似文献
12.
Junhui Xu Yazhen Wang Hongxin Qiu Yumin Zhang 《Russian Journal of Electrochemistry》2014,50(6):531-536
We report on a novel electrochemical method to detect trace pentachlorophenol (PCP) by using a chitosan (CS) modified carbon paste electrode (CS/CPE). Compared with that at a bare carbon paste electrode (CPE), the current response was greatly improved at the CS/CPE due to the enhancement effect of CS. Under optimal working conditions, the oxidation peak current of PCP was proportional to its concentration in the range of 1.0 × 10?7 to 5.0 × 10?6 and 5.0 × 10?6 to 1.0 × 10?4 mol/L, with an extremely low detection limit of 4.0 × 10?8 mol/L. Our method was successfully used to detect the PCP concentration in vegetable samples. 相似文献
13.
A new electrochemical method was proposed for the determination of adenosine‐5′‐triphosphate (ATP) based on the electrooxidation at a molecular wire (MW) modified carbon paste electrode (CPE), which was fabricated with diphenylacetylene (DPA) as the binder. A single well‐defined irreversible oxidation peak of ATP appeared on MW‐CPE with adsorption‐controlled process and enhanced electrochemical response in a pH 3.0 Britton‐Robinson buffer solution, which was due to the presence of high conductive DPA in the electrode. The electrochemical parameters of ATP were calculated with the electron transfer coefficient (α) as 0.54, the electron transfer number (n) as 1.9, the apparent heterogeneous electron transfer rate constant (ks) as 2.67 × 10?5 s?1 and the surface coverage (ΓT) as 4.15 × 10?10 mol cm?2. Under the selected conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10?7 mol L?1 to 2.0 × 10?3 mol L?1 with the detection limit as 1.28 × 10?8 mol L?1 (3σ) by sensitive differential pulse voltammetry. The proposed method showed good selectivity without the interferences of coexisting substances and was successful applied to the ATP injection samples detection. 相似文献
14.
Electrocatalytic oxygen reduction was studied on a RuxFeySez(CO)n cluster catalyst with Vulcan carbon powder dispersed into a Nafion film coated on a glassy carbon electrode. The synthesis
of the electrocatalyst as a mixture of crystallites and amorphous nanoparticles was carried out by refluxing the transition
metal carbonyl compounds in an organic solvent. Electrocatalysis by the cluster compound is discussed, based on the results
of rotating disc electrode measurements in a 0.5 M H2SO4. A Tafel slope of −80.00±4.72 mV dec−1 and an exchange current density of 1.1±0.17×10−6 mA cm−2 was calculated from the mass transfer-corrected curve. It was found that the electrochemical reduction reaction follows the
kinetics of a multielectronic (n=4e−) charge transfer process producing water, i.e. O2+4H++4e−→2H2O.
Electronic Publication 相似文献
15.
A multi-wall carbon nanotube (MWNT)/cetyl pyridine bromine (CPB) composite film modified glassy carbon electrode (GCE) was
developed for the electrochemical determination of hymecromone in phosphonate buffer. Electrochemical behaviour of hymecromone
at the composite film electrode was investigated with voltammetry. Compared with an irreversible oxidation of hymecromone
at the bare GCE, the oxidation peak current was enhanced greatly at the film electrode. Some parameters such as pH, scan rate,
accumulation potential and accumulation time were optimized. Under optimal conditions, an oxidation peak at 0.82 V was employed
to determine hymecromone electrochemically. A linearity between the oxidation peak current and the hymecromone concentration
was obtained in the range of 3.0 × 10−7 − 2.0 × 10−5 mol 1−1 with a detection limit of 8.0 × 10−8 mol 1−1. The proposed procedure was successfully applied to assay hymecromone in pharmaceutical formulation with satisfactory results.
The text was submitted by the authors in English. 相似文献
16.
I. E. Animitsa E. N. Dogodaeva S. S. Nokhrin O. A. Kosareva A. Ya. Neiman 《Russian Journal of Electrochemistry》2010,46(7):734-740
Perovskite phases Ba3In2ZrO8 and Ba4In2Zr2O11 with the nominal concentration of structural oxygen vacancies 1/9 and 1/12, respectively, were synthesized by solid-phase
and solution methods. X-ray diffraction showed cubic symmetry of both phases with the unit cell parameter a = 0.4193(2) and 0.4204(3) nm, respectively. The absence of superstructural lines resulted in the conclusion on statistical
arrangement of oxygen vacancies. Thermogravimetry and mass spectrometry proved that both phases can reversibly absorb water
from gas phase (pH2O = 2 × 10−2 atm) with observed correlation between the concentration of oxygen vacancies and amount of absorbed water. The total water
amount was up to 0.9 mol per formula unit or, if recalculated for perovskite unit ABO3, 0.3 and 0.23 mol H2O, respectively. The temperature curves of coductivity in the atmosphere with various partial water vapor pressures (pH2O = 3 × 10−5 and 2 × 10−2 atm) showed significantly higher conductivity and lower activation energy (0.52 eV) in humid atmosphere due to proton transfer.
The proton conductivity is up to 5 × 10−4 Ohm−1 cm−1 at 300°C for Ba3In2ZrO8 specimen. IR spectrometry showed that protons in the structure exist primarily in OH-groups. 相似文献
17.
Jiming Xu Yanping Wang Yuezhong Xian Hui Li Litong Jin K. Tanaka H. Haraguchi 《Chromatographia》2002,56(7-8):449-453
Summary A sensitive ion-exclusion chromatographic method has been developed for determination of oxalate, thiosulfate, and thiocyanate.
The method is based on separation of these anions on a polymethacrylate-based, weakly acidic cation-exchange resin (TSKgel
OApak-A) and detection by means of a glassy carbon (GC) electrode electrochemically modified with polyvinylpyridine (PVP),
palladium, and iridium oxide (PVP/Pd/IrO2). The electrochemical behavior of oxalate, thiosulfate, and thiocyanate at this chemically modified electrode (CME) have
been investigated by cyclic voltammetry. The results indicated that electrocatalytic oxidation of these anions by the electrode
was efficient and that the sensitivity, stability, and lifetime of the electrode were relatively high. Combined with ion-exclusion
chromatography the PVP/Pd/IrO2 electrode was used as the working electrode for amperometric detection of these anions. All linear ranges were over two orders
of magnitude and detection limits, defined asS/N=3, were 9.0×10−7 mol L−1 for oxalate, 6.7×10−7 mol L−1 for thiosulfate, and 5.6×10−7 mol L−1 for thiocyanate. Correlation coefficients were all>0.998. Coupled with microdialysis sampling the method has been successfully
applied to the determination of oxalate, thiosulfate, and thiocyanate in urine. 相似文献
18.
Mesoporous SiO2 of SBA-15 is reported to modify carbon paste electrodes for detecting epinephrine (EP). Carbon paste electrodes modified with synthesized SBA-15 show high sensitivity for voltammetric determination of EP, which is attributed to the strong adsorption ability of SBA-15 to EP and large surface area of the working electrode resulted from SBA-15 modification. The effects of pH value, amount of SBA-15 and scan rate were investigated. Under optimum conditions, the anodic peak current of EP was proportional to its concentration over the range from 1.0 × 10?6 to 6.0 × 10?5 mol L?1 and the limit of detection was 6.0 × 10?7 mol L?1. The results show mesoporous SiO2-modified carbon paste electrodes, particularly SBA-15-modificd electrodes, create new opportunities for sensitive, simple and suitable method in the electrochemical analysis of EP. 相似文献
19.
Gold nanoparticles (nano Au)/titanium dioxide (TiO2) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization
detection. The immobilization of nano Au and TiO2 microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization
events were monitored with EIS using [Fe(CN)6]3−/4− as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with
this DNA electrochemical sensor. The dynamic detection range was from 1.0×10−12 to 1.0×10−8 mol/L DNA and a detection limit of 2.3×10−13 mol/L could be obtained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene
from the real sample of a kind of transgenic soybean was also satisfactorily detected.
Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020), Doctoral Foundation of the
Ministry of Education of China (Grant No. 20060426001) and Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8) 相似文献
20.
Utilizing the fascinating properties of montmorillonite calcium (MMT-Ca), such as huge cationic exchange capacity, strong
adsorptive ability, high chemical and mechanical stability, an MMT-Ca modified carbon paste electrode (CPE) was constructed
for the sensitive determination of Pb2+. In 0.01 mol·L−1 HCl, Pb2+ was firstly exchanged and accumulated on an MMT-Ca modified CPE surface and secondly reduced to Pb at −0.90 V. In the following
potential sweep from −0.90 to −0.50 V, reduced Pb was oxidized, resulting in an obvious stripping peak at −0.58 V. After optimizing
the parameters, such as determining medium, content of MMT-Ca, accumulation potential and time, an electrochemical method
was developed for the analysis of Pb2+. Compared with bare CPE, the MMT-Ca modified CPE significantly enhances the sensitivity of Pb2+ analysis. The limit of detection is evaluated to be 6.0 × 10−9 mol L−1 Pb2+. Finally, this method was successfully employed to determine trace levels of Pb2+ in water samples.
The first two authors contribute equally do this work 相似文献