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A new PVC membrane electrode for Zn2+ ions based on tetra(2-aminophenyl) porphyrin (TAPP) as membrane carrier is prepared. The sensor exhibits a linear stable response over a wide concentration range (5.0×10−5 to 1.0×10−1 M) with a slope of 26.5 mV/decade and a limit of detection 3.0×10−5 M (1.96 ppm). It has a response time of about l0 s and can be used for at least 8 months without any divergence in potential. The propose membrane sensor revealed good selectivities for Zn2+ over a wide variety of other metal ions and can be used in pH range of 3.0–6.0. It was successfully applied to the direct determination of zinc in a pharmaceutical sample and also as an indicator electrode in potentiometric titration of Zn2+ ions. 相似文献
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Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) were investigated successfully in liquid crystal films of didodecyldimethylammonium bromide (DDAB) on pyrolytic graphite (PG) electrodes in aqueous solution. This new bi-CoPc-surfactant film modified electrode could reduce aggregation of bi-CoPc in aqueous solution, which was confirmed by the electronic absorption spectra in the visible region and images of transmission electron microscopy (TEM). The charge transport diffusion coefficient (Dct) and apparent heterogeneous electrode reaction rate constant (ks) for this modified electrode were estimated. The reduction of bi-CoPc ligand showed excellent electrocatalytic ability for the reduction of trichloroacetic acid (TCA) and catalytic current had a linear relationship with the concentration of TCA in the range of 3×10−5-7.5×10−3 M. The reduction of bi-Co(III)Pc/bi-Co(II)Pc couple exhibited new pattern of catalytic reactivity in the reduction of oxygen. Peak current for the cathodic reduction of oxygen is proportion to the square root of the scan rate in the range of 5-1000 mV s−1 in oxygen-saturated solution. 相似文献
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The determination of zinc ion (1-60 ng ml−1) by anodic square-wave stripping voltammetry on an anion-exchange perfluorinated polymer Tosflex mercury film electrodes (TMFE) was evaluated. The detection limit was 0.1 ng ml−1 Zn(II). The effect of various organic compounds (gelatin, albumin, starch, camphor, humic acid, Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) is explored. The results indicate that due to the size-exclusion and ion-exchange properties of Tosflex film, the TMFE is considerably more resistant to organic interference than the bare mercury film electrode. 相似文献
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Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid crystal properties and display a hexago-nal columnar discotic columnar (Colh) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, 1H NMR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence, and surface photovoltage spectroscopy. 相似文献
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A sensitive procedure is presented for the voltammetric determination of nickel. The procedure involves an adsorptive accumulation of nickel 1-nitroso-2-napthol (NN) complex on a bismuth film electrode prepared ex situ by electrodeposition. The most suitable operating conditions and parameters such as pH, ligand concentration (CNN), adsorptive potential (Eads), adsorptive time (tads), scan rate and others were selected and the determination of nickel in aqueous solutions using the standard addition method was possible. The adsorbed Ni-NN complex gives a well defined cathodic stripping peak current at −0.70 V, which was used for the determination of nickel in the concentration range of 10.0-70.0 μg L−1 (pH 7.5; CNN 6.5 μmol L−1; Eads −0.30 V; tads 60 s) with a detection limit of 0.1 μg L−1. The relative standard deviation for a solution containing 10.0 μg L−1 of Ni(II) was 3.5% (n = 4). The proposed method was validated determining Ni(II) in certified reference waste water (SPS-WW1) and Certified Reference Water for Trace Elements (TMDA 51.3) with satisfactory results. Then lake water samples were analyzed. 相似文献
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Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid
crystal properties and display a hexagonal columnar discotic columnar (Colh) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, 1H NIVR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence,
and surface photovoltage spectroscopy.
Supported by the National Natural Science Foundation of China (Grant No. 59783001), the Natural Science Foundation of Shandong
Province (Grant No. Y2006B41), the Foundation of Shandong Provincial Education Department (Grant No. J06A53), the Natural
Science Foundation of Shandong University of Technology (Grant No. 2004KJM15) and Doctor Foundation of Shandong University
of Technology 相似文献
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A mercury-free electrochemical sensor for the determination of thallium(I) based on the rotating-disc bismuth film electrode 总被引:1,自引:0,他引:1
A bismuth film electrode was tested and proposed as an environmentally friendly sensor for the determination of trace levels of Tl(I) in non-deoxygenated solutions. Determination of thallium was made by anodic stripping voltammetry at a rotating-disc bismuth film electrode plated in situ, using acetate buffer as the supporting electrolyte. The stripping step was carried out by a square wave potential-time excitation signal. A univariate optimisation study was performed with several experimental parameters as variables. Under the selected optimised conditions, a linear calibration plot was obtained in the submicromolar concentration range, allowing the electrochemical determination of thallium in trace amounts; the calculated detection limit was 10.8 nM and the relative standard deviation for 15 measurements of 0.1 μM Tl(I) was ±0.2%, for a 120 s accumulation time. Interference of other metals on the response of Tl(I) was investigated. Application to real environmental samples was tested. The bismuth film electrode appears to be a promising tool for electroanalytical purposes, ensuring the use of clean methodology. 相似文献
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Catalytic adsorptive stripping determination of trace chromium (VI) at the bismuth film electrode 总被引:1,自引:0,他引:1
A sensitive adsorptive stripping voltammetric protocol at a bismuth-coated glassy-carbon electrode for trace measurements of chromium (VI) in the presence of diethylenetriammine pentaacetic acid (DTPA) is described. The new protocol is based on accumulation of the Cr-DTPA complex at a preplated bismuth film electrode held at −0.80 V, followed by a negatively-going square-wave voltammetric waveform. Factors influencing the stripping performance including the film preparation, solution pH, DTPA and nitrate concentrations, deposition potential and deposition time, have been optimized. The resulting performance compares well with that observed for analogous measurements at mercury film electrodes. A preconcentration time of 7 min results in a detection limit of 0.3 nM Cr(VI) and after 2 min a relative standard deviation at 20 nM of 5.1% (n = 25). Applicability to river water samples is demonstrated. The attractive behavior of the new “mercury-free” chromium sensor holds great promise for on-site environmental and industrial monitoring of chromium (VI). Preliminary data in this direction using bismuth-coated screen-printed electrodes are encouraging. 相似文献
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Naseri NG Baldock SJ Economou A Goddard NJ Fielden PR 《Analytical and bioanalytical chemistry》2008,391(4):1283-1292
Catalytic adsorptive stripping voltammetry (CAdSV) has been demonstrated at a bismuth film electrode (BiFE) in an injection-moulded
electrochemical micro-flow cell. The polystyrene three-electrode flow cell was fabricated with electrodes moulded from a conducting
grade of polystyrene containing 40% carbon fibre, one of which was precoated with Ag to enable its use as an on-chip Ag/AgCl
reference electrode. CAdSV of Co(II) and Ni(II) in the presence of dimethylglyoxime (DMG) with nitrite employed as the catalyst
was performed in order to assess the performance of the flow cell with an in-line plated BiFE. The injection-moulded electrodes
were found to be suitable substrates for the formation of BiFEs. Key parameters such as the plating solution matrix, plating
flow rate, analysis flow rate, solution composition and square-wave parameters have been characterised and optimal conditions
selected for successful and rapid analysis of Co(II) and Ni(II) at the ppb level. The analytical response was linear over
the range 1 to 20 ppb and deoxygenation of the sample solution was not required. The successful coupling of a microfluidic
flow cell with a BiFE, thereby forming a “mercury-free” AdSV flow analysis sensor, shows promise for industrial and in-the-field
applications where inexpensive, compact, and robust instrumentation capable of low-volume analysis is required. 相似文献
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The bismuth film electrode (BiFE), in combination with anodic stripping voltammetry, offers convenient measurement of low concentrations of tin. The procedure involves simultaneous in situ formation of the bismuth film electrode on a glassy carbon substrate electrode, together with electrochemical deposition of tin, in a non-deaerated model solution containing bismuth ions, catechol as complexing agent and the metal analyte, followed by an anodic stripping scan. The BiFE is characterized by an attractive electroanalytical performance, with two distinct voltammetric stripping signals corresponding to tin, accompanied with low background contributions. Several experimental parameters were optimized, such as concentration of bismuth ions and catechol, deposition potential, deposition time and pH of the model solution. In addition, a critical comparison is given with bare glassy carbon and mercury film electrodes, revealing the superior characteristics of BiFE for measurement of tin. BiFE exhibited highly linear behavior in the examined concentration range from 1 to 100 μg L−1 of tin (R2 = 0.997), an LoD of 0.26 μg L−1 tin, and good reproducibility with a calculated R.S.D. of 7.3% for 10 μg L−1 tin (n = 10). As an example, the practical applicability of BiFE was tested with the measurement of tin in a real sample of seawater. 相似文献
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JIN Bao-Kang ZHANG Jian-Rong ZHANG Zu-XunDepartment of Chemistry Nanjing University Nanjing Jiangsu China 《中国化学》1996,14(4):338-347
An analytical expression describing voltammetric behaviors responses at microdisk electrode for various diffusion conditions and degrees of reversibility is reported in this paper. Results of theoretical calculation made it possible to use cyclic voltammetry to evaluate heterogeneous rate constants under intermediate diffusion conditions. At relatively low scan rate, the distortion of current-voltage can be reduced due to small iR drops and charging current. The effects of transfer coefficient, a, kinetic parameter, (=k0r/4D), and switching potential, s, on potential peak separation are discussed in detail. The relationship obtained in this paper between potential peak separation and \ is in good agreement with that in Ref. 14, whose authors have got their results by using digital simulation technique. After the experiment of Fe(CN)64- oxidation, k0 and a were obtained by the theory of this paper. The result agrees with that in Ref. 19. 相似文献
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Makoto Yuasa Kenichi Oyaizu Aritomo Yamaguchi Masuhide Ishikawa Katsuya Eguchi Tomohiro Kobayashi Yuujiro Toyoda Satoshi Tsutsui 《先进技术聚合物》2005,16(8):616-621
Oxidative polymerization of bromoiron(III) meso‐tetrakis(3‐thienyl)porphyrin gave a novel polymeric porphyrin complex randomly crosslinked at the 2,5‐positions of the peripheral thienyl groups. The electrical semiconductivity of ca. 10?5 S/cm after I2 doping indicated that the polymer had a π‐conjugated structure with a moderate delocalization of π electrons over the thienylporphyrin units. PM3 calculations for free‐base models revealed that HOCO (the highest occupied crystal orbital) band width was reduced by introduction of the porphyrin moieties into the thienylene backbone and yet low HOCO‐LUCO (the lowest unoccupied crystal orbital) gap was maintained, which accounted for the relatively low electrical conductivity of the porphyrin polymer. The modified electrode prepared by electropolymerization was redox‐active due to the presence of iron(II/III) couple and the semiconductivity of the film, which served as a novel non‐enzymatic electrochemical sensor for superoxide anion radical based on the facile electrocatalytic oxidation of the superoxide. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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LIU Hong-Guo FENG Xu-Sheng YANG Kong-ZhangInstitute of Colloid Interface Chemistry Shandong University Jinan Shandong ChinaCHENG Chuan-Fu LI Jian Department of Physics Shandong Normal University Jinan Shandong ChinaLIANG Wei-AnDepartment of Chemistry Shandong University Jinan Shandong China 《中国化学》1995,13(5):415-422
The structure and properties of mixed monolayer or LB film of 5,10,15,20-tetra-4-oxy(2-stearic acid)phenyl porphyrin/C60 were studied. A isotherms and small angle X-ray diffraction (SAXD) results show that C60 molecules were incorporated into the cavities of por-phyrin molecules in mixed monolayer and LB film . UV-vis spectra of mixed LB films show that the absorption intensity of porphyrin varied compared with pure porphyrin film, probably arising from the interactions between C60 and porphyrin ring. C60 molecules in mixed systems are well-dispersed. The TPP(CO2H)/C60 mixed LB film is a kind of two-dimensional host-guest system. 相似文献
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A poly(4-vinylpyridine)/mercury film electrode (PVP/MFE) was used for the determination of trace thallium(III) by square-wave anodic stripping voltammetry (SWASV). Thallium(III) is preconcentrated onto the PVP/MFE as the anionic forms in chloride medium by the ion-exchange effect of the PVP. The high solubility of thallium in mercury further facilitates the accumulation effect. Various factors influencing the determination of thallium(III) were thoroughly investigated. This modified electrode displayed good resistance to interferences from surface-active compounds and common ions and increased sensitivity when used in conjunction with SWASV. In addition, detection can be achieved without deoxygenation and the electrode can be easily renewed. Applicability to various water samples is illustrated. 相似文献