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1.
A flow injection method using 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol-(Nitro-PAPS) as a new chromogenic reagent is presented for sensitive and rapid determination of vanadium. Nitro-PAPS reacts with vanadium(V) in weakly acidic medium to form a water soluble complex of molar absorptivity of 8.0 × 104L mol–1 cm–1 at 592 nm (maximum absorption wavelength), which permits the straightforward application of a flow injection system to the sensitive determination of vanadium. Under the optimum conditions established, a linear calibration graph was obtained in the range 1–120 ng mL–1. The relative standard deviation for 60 ng mL–1 vanadium was 2.2% (n = 5) and the limit of detection was 1 ng mL–1. The sample throughput is about 40 h–1. Most inorganic and organic anions examined did not interfere even at concentrations of 3000–6000 times of vanadium. Interference from cobalt(II), copper(II) and nickel(II) at 200ng mL–1 levels can be overcome by the addition of N-(dithio-carboxy)sarcosine. The recoveries for each 20 and 10 ng mL–1 vanadium added to the river water were 98 and 97%, respectively.The authors express their thanks to Miss Miho Suzuki and Miss Hiroyo Yamada for their experimental assistance in part. 相似文献
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己硫醇二茂铁复合金纳米粒子修饰电极对多巴胺的催化性能研究 总被引:3,自引:0,他引:3
将自行合成的己硫醇二茂铁自组装于金纳米粒子表面,获得己硫醇二茂铁复合金纳米粒子(Au@S(CH2)6Fc)。采用滴涂法将制备的复合纳米粒子固定于玻碳电极表面,制备Au@S(CH2)6Fc修饰电极,采用循环伏安法对修饰电极的电化学性能进行考察。将制备的修饰电极用于对神经递质多巴胺(DA)的催化氧化性能研究。结果表明,该修饰电极对DA具有显著的催化氧化作用,线性范围为1.0×10^-6-2.6×10^-3mol/L,检出限为3.0×10^-7mol/L。 相似文献
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A chemically modified electrode (CME) containing 1-(2-pyridylazo-2-naphthol is evaluated for its ability to preconcentrate bismuth(III) prior to quantification by voltammetry. The CME approach is shown to be sufficiently sensitive for sub-nanomolar concentrations to be determinable after chemical deposition for 60 sec. Further, when the bismuth is deposited from iodide-containing sulphuric acid media, the discrimination against interference by copper(II) is significantly better than that obtained with conventional stripping analysis. The results obtained for Bi(III)( in an NBS reference solution agree well with the recommended value. 相似文献
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XU He ZHENG QiaoLi YANG Ping LIU JianShe XING SuJie & JIN LiTong School of Environmental Science Engineering Donghua University Shanghai China 《中国科学B辑(英文版)》2011,(6)
A simple and rapid approach for the electrochemical synthesis of Ag nanoparticles-coated gold nanoporous film (AgGNF) on a gold substrate was reported. The solid gold electrode (SGE) was directly anodized under a high potential of 5 V, and then reduced to obtain gold nanoporous film (AuNF) by freshly prepared ascorbic acid. The Ag nanoparticles (AgNPs) were grown on the AuNF electrode by potential-step electrodeposition. The resulting AgGNF composites electrodes were characterized by scanning electron micro... 相似文献
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Francesca Zavarise 《Analytica chimica acta》2010,668(2):177-4532
The preparation, characterization and analytical applications of gold electrodes modified with ω-mercapto alkyl/aryl sulfonates are described. The devices resulted effective for the determination of free and labile Pb(II) in water samples by anodic stripping voltammetry (Edep = −600 mV) and in particular 2-mercaptobenzimidazole-5-sulfonate (MBIS) offered the best performances with detection limit of 0.4 μg L−1.Quantitative stripping of Pb from the electrode surface during the anodic scan, is obtained using sodium citrate buffer (pH = 9.0) as supporting electrolyte. Natural waters were analysed by standard addition method with good recoveries (mean percentage = 97%); no fouling effects due to humic acids or other organic constituents were observed in the reported conditions. 相似文献
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An amperometric sensor for amino acids based on the immobilization of amino acid oxidase on the surface of a CuPtCl6/GC is described. The amperometric current is due to the oxidation of H2O2 liberated during the enzyme reaction on the surface of the enzyme electrode. The electrode response characteristics as well
as kinetic parameters have been evaluated. The enzyme electrode was characterized as an electrochemical biosensor, which was
used as detector in high performance liquid chromatography (HPLC) for the determination of a mixture of amino acids with satisfactory
results.
Received: 31 Jaunary 2000 / Revised: 31 March 2000 / Accepted: 3 April 2000 相似文献
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将金纳米粒子电沉积在石墨烯修饰的玻碳电极表面,研究了维生素B6(VB6)在该修饰电极上的电化学行为。扫描电镜用于该修饰电极组装过程的形貌表征。实验结果表明:VB6在此修饰电极上出现一个良好的氧化峰,在最佳实验条件下,其氧化峰电流与VB6浓度在5.0×10-8~2.0×10-5 mol/L范围内呈线性关系,其线性回归方程为I(μA)=0.5697c(μmol/L)+0.06275,R=0.9992,检出限为2.0×10-8 mol/L(S/N=3)。一些常见的干扰物质如抗坏血酸不干扰VB6的检测。方法已用于片剂中VB6的含量的检测。 相似文献
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In the paper, a new kind of vitamin B12 (acquo-cobalamine) chemically modified electrode was fabricated and applied in capillary zone electrophoresis coupled with amperometric detection (CZE-AD) for simultaneous determination of six antioxidants in fruits and vegetables. The catalytic electrochemical properties of the chemically modified electrode could obviously enhance oxidation peak heights responses by about five times to glutathione, ascorbic acid, vanillic acid, chlorogenic acid, salicylic acid, and caffeic acid compared with common carbon disk electrode. Furthermore, the effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CZE-AD were investigated. Under the optimum conditions, the six analytes could be completely separated and detected in a borate-phosphate buffer (pH 8.4) within 15 min. Their linear ranges were from 2.5 × 10−7 to 1.0 × 10−4 mol L−1 and the detection limits were as low as 10−8 mol L−1 magnitude (S/N = 3). The proposed method has been successfully employed to monitor the six analytes in practical samples with recoveries in the range 96.0-106.0% and RSDs less than 5.0%. Above results demonstrate that capillary zone electrophoresis coupled with electrochemical detection using vitamin B12 modified electrode as detector is of convenient preparation, high sensitivity, good repeatability, and could be used in the rapid determination of practical samples. 相似文献
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Newton L Dias Filho Devaney R do Carmo Laércio Caetano André H Rosa 《Analytical sciences》2005,21(11):1359-1363
A mercury-sensitive chemically modified graphite paste electrode was constructed by incorporating modified silica gel into a conventional graphite paste electrode. The functional group attached to the (3-chloropropyl) silica gel surface was 2-mercaptoimidazole, giving a new product denoted by 3-(2-thioimidazolyl)propyl silica gel, which is able to complex mercury ions. Mercury was chemically adsorbed on the modified graphite paste electrode containing 3-(2-thioimidazolyl)propyl silica (TIPSG GPE) by immersion in a Hg(II) solution, and the resultant surface was characterized by cyclic and differential pulse anodic stripping voltammetry. One cathodic peak at 0.1 V and other anodic peak at 0.34 V were observed on scanning the potential from -0.1 to 0.8 V (0.01 M KNO3; v = 2.0 mV s(-1) vs. Ag/AgCl). The anodic peak at 0.34 V show an excellent sensitivity for Hg(II) ions in the presence of several foreign ions. A calibration graph covering the concentration range from 0.02 to 2 mg L(-1) was obtained. The detection limit was estimated to be 5 microg L(-1). The precision for six determinations of 0.05 and 0.26 mg L(-1) Hg(II) was 3.0 and 2.5% (relative standard deviation), respectively. The method can be used to determine the concentration of mercury(II) in natural waters contaminated by this metal. 相似文献
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I. S. El-Hallag A. M. Hassanein M. M. Ghoneim 《Monatshefte für Chemie / Chemical Monthly》1995,126(10):1075-1085
Summary Cyclic voltammetry (CV), convolution-deconvolution transformation of current, chronopotentiometry (CP), and digital simulation studies were used to evaluate the kinetic parameters of the electrode reaction of the hetero-bimetallic complex [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF
6
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in dichloromethane at a glassy carbon electrode (GCE). It was found that the complex undergoes a reduction step at –0.895±0.01 V and two anodic steps at +0.903±0.01 V and 1.370±0.01 V. The reduction and oxidation steps are followed by a rapid chemical process. On the basis of the electrochemical results, an overall oxidation process was found to proceed as EEC, while the reduction process proceeds according to an ECEC scheme.
Elektrochemische Untersuchung des hetero-bimetallischen Komplexes [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF 6 – mit einer Glaskohlenstoffelektrode
Zusammenfassung Cyclische Voltammetrie (CV), Strom-Konvolution-Dekonvolution, Chronopotentiometrie und digitale Simulation wurden zur Bestimmung der kinetischen Parameter der Reaktion des hetero-bimetallischen Komplexes [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF 6 – an einer Glaskohlenstoffelektrode (GCE) in Dichlormethan eingesetzt. Der Komplex zeigt eine Reduktionsstufe bei –0.895±0.01 V und zwei anodische Stufen bei 0.903±0.01 V und 1.370±0.01 V. Auf die Reduktions-und Oxidationsschritte folgt unmittelbar ein schneller chemischer Prozeß. Aus den elektrochemischen Ergebnissen läßt sich ein Gesamtoxidationsprozeß nach einem EEC — Schema ableiten, während die Reduktion nach einem ECEC — Schema verläuft.相似文献
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A sensitive flow-injection system for l-lactate is described. Lactate dehydrogenase, LDH, and glutamic-pyruvic transaminase, GPT, were co-immobilized on a gluteraldehyde-activated porous silica support and used in a packed-bed enzyme reactor. l-lactate is oxidized to pyruvate in the presence of NAD+, an equivalent amount of NADH being produced. The equilibrium of the reaction is unfavourable, but by co-immobilizing LDH with GPT and adding l-glutamate, the pyruvate reacts and enough force is obtained to drive the oxidation of l-lactate totally to the product side. The NADH formed is then detected electrocatalytically at an electrode chemically modified with Meldola Blue, operated at 0 mV vs. Ag/AgCl. The system responds linearly to injected samples (25 μl) of l-lactate in the concentration range 10 μM–1.5 mM. The maximum sample throughput is 30 h?1. The LDH/GPT reactor was stable for four weeks when used daily at optimal pH 8.8. 相似文献
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Chemically modified electrodes, constructed by adsorption of 4,4'-dithiodipyridine onto a polyvinylferrocene-treated gold surface, were employed for the amperometric detection of cytochrome c following size-exclusion chromatography. The electrode response was nearly reversible, permitting quantitation both of the ferro-form of the protein at +0.15 V vs. Ag/AgCl and of the ferri-form at -0.15 V. The limit of detection for the reduced species was 3 pmol injected, and the response was linear over three orders of magnitude. Using the chemically modified electrode approach, cytochrome c monitoring was sufficiently selective that the compound could be determined in human plasma pretreated only by dilution and particulate filtration. 相似文献
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A novel sensor for the determination of nitrite anion () was fabricated by electrodeposition of toluidine blue. The sensor exhibited good catalytic activity toward the electrochemical
oxidation of nitrite. Amperometry was carried out to determine the concentration of . A linear response in the range from 1.0×10−7 to 1.52×10−5 M with a substantially low detection limit of 5×10−8 M (S/N=3) was obtained. The proposed sensor had a feature of high sensitivity of 4.7×105 μA M−1 cm−2. The possible interference from several common ions was tested. This sensor was applied to the amperometric determination
of nitrite in food samples, and the results were consistent with those obtained with the standard spectrophotometric procedure. 相似文献
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《Electrochemistry communications》2007,9(9):2157-2162
An amperometric method for the rapid detection of Escherichia coli (E. coli) by flow injection analysis (FIA) using an IrO2–Pd chemically modified electrode (CME) was developed in this paper. The method is based on a good marker β-d-galactosidase which was found in E. coli strains. β-d-galactosidase was produced by the induction of isopropyl β-d-thiogalactopyranoside (IPTG) and released from E. coli cells through the permeabilization of both polymyxin B nonapeptide and lysozyme to E. coli cells wall. The released β-d-galactosidase could catalyze the hydrolysis of the substrate p-aminophenyl β-d-galactopyranoside (PAPG) in the culture medium to produce 4-aminophenol which was proportional to the concentration of E. coli. Hence, E. coli could be detected by the determination of 4-aminophenol. An IrO2–Pd CME, which showed high sensitivity in determination of 4-aminophenol, was prepared as the electro-detector in FIA. The amplified response current of 4-aminophenol obtained at the IrO2–Pd CME was linear with the concentration of E. coli ranging from 2.0 × 102 to 1.0 × 106 cfu/mL, the detection limit of this method to E. coli was 150 cfu/mL and the complete assay could be performed in 3 h. 相似文献
20.
Electrochemical detection of copper(II) at a gold electrode modified with a self-assembled monolayer of penicillamine 总被引:1,自引:0,他引:1
A penicillamine (PCA) self-assembled monolayer (SAM) was prepared on a gold electrode. It has been found that the modified
electrode exhibited a selective response to copper ions. As demonstrated by cyclic voltammetric experiments, the SAM-based
electrode showed an attractive ability to preconcentrate efficiently traces of copper(II) from solutions. Under optimum conditions,
the anodic peak current was proportional to the concentration of Cu(II) in the range from 8.0 × 10−7 to 1.0 × 10−4 M with a detection limit of 4.0 × 10−7 M. Moreover, this modified gold electrode is also characterized by excellent repeatability, showing a relative standard deviation
of 3.2% for nine successive measurements of 1.0 × 10−5 M Cu(II). The PCA/Au SAM gold electrode was used for the determination of Cu(II) in a tap water sample and the results showed
a good agreement with the data obtained by atomic emission spectrometry.
The text was submitted by the authors in English. 相似文献