排序方式: 共有86条查询结果,搜索用时 78 毫秒
1.
《Electroanalysis》2006,18(23):2361-2368
The oxidation of benzophenone‐4 (2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid) at glassy carbon electrode gives rise to stable redox active electropolymerized film during repetitive potential cycling between 0 to 1.3 V (Ag/AgCl). Cyclic voltammogram of poly(benzophenone‐4) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 51 mV/pH. The electrocatalytic behavior of poly(benzophenone‐4) film modified electrode towards oxidation of dopamine, ascorbic acid and reduction of nitrite was investigated. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(benzophenone‐4) film compared to bare glassy carbon electrode. For dopamine, the overpotential was reduced about 180 mV. Feasibility of utilizing poly(benzophenone‐4) film coated electrode in analytical estimation of dopamine, ascorbic acid and nitrite was also demonstrated. 相似文献
2.
Franco Cataldo 《Tetrahedron》2004,60(19):4265-4274
The products of the electric arc between graphite electrodes have been investigated by high performance liquid chromatography-diode-array detector (HPLC-DAD) analysis in various media: distilled water, liquid nitrogen, methanol, ethanol, n-hexane and benzene. In distilled water, hydrogen capped polyynes H-(CC)n-H were the unique products demonstrating that carbon is supplied by the graphite electrodes while hydrogen is supplied by the solvent plasmalysis (in this case water plasmalysis). Arcing graphite electrodes in liquid nitrogen produces cyanopolyynes: NC-(CC)n-CN demonstrating that in this case the end groups of the polyyne chains are supplied by molecular nitrogen plasmalysis caused by the electric arc. Graphite arcing in methanol and ethanol produces very clean solutions (by-products negligible or absent) of hydrogen-capped polyynes with C8H2 as the main product accounting for more than 70 mol percent of the total polyyne concentration. By replacing graphite electrodes with titanium electrodes in methanol or in ethanol, polyynes are not formed at all; only trace amounts of polycyclic aromatic hydrocarbons (PAHs) were detected. When arcing with graphite electrodes is conducted in n-hexane or in benzene, polyyne formation is accompanied by a significant production of PAH, especially in benzene. These results have been rationalized in terms of carbonization or coking tendency of a given solvent. The effect of using titanium electrodes in place of graphite electrodes has been investigated also in n-hexane and in benzene as well as the effects of very high electric current intensity employed to ignite and sustain the submerged electric arc. 相似文献
3.
Improved preparative electrochromatography column design 总被引:2,自引:0,他引:2
Improved chromatography column fittings were developed for the efficient and reliable application of an electric field to a preparative chromatography column (a process termed electrochromatography). The improved fittings contained electrodes in close proximity to the column packing media and allowed uniform electric fields to be applied. Membranes in the fittings prevented mixing of the electrode and the column eluent buffers. The membranes prevented gases and electrolytic products generated in the electrode chamber from entering the column eluent buffer. An electrode buffer solution was pumped through the electrode chamber to a large external container. The circulation of buffer through the electrode chamber removed the gases and electrolytic products and ensured a uniform electric field by helping to maintain a constant buffer composition. The membranes prevented macromolecules being separated on the column from coming in contact with the electrodes. 相似文献
4.
Gino Bontempelli Nicola Comisso Rosanna Toniolo Gilberto Schiavon 《Electroanalysis》1997,9(6):433-443
Electroanalytical sensors, suitable for the analysis and monitoring of electroactive analytes present in gaseous phase or low-conductive liquid media, and based on electrodes in close contact with perfluorinated ion-exchange polymers are reviewed. The basic operative mechanism of these sensors, in which ion-exchange polymers act as solid polymer electrolytes (SPE's), is thoroughly discussed, while stressing the fundamental reasons why their behavior differs from that of conventional membrane electrodes. The procedures for preparing composite working electrodes by coating one side of ion-exchange membranes with stable porous films of conductive materials are described, along with the most common strategies followed to assemble this type of sensors. Useful examples of measurements in electrolyte-free media of inorganic and organic electroactive species of interest mainly for environmental analysis are given. Future prospects for the development of these sensors are also discussed. 相似文献
5.
Polymer-Mercury Coated Screen-Printed Sensors for Electrochemical Stripping Analysis of Heavy Metals
Ilaria Palchetti Sanaa Majid Alessandra Kicela Giovanna Marrazza Marco Mascini 《International journal of environmental analytical chemistry》2013,93(7-8):701-711
In the perspective of in-field stripping analysis of heavy metals, the use and disposal of toxic mercury solutions (necessary to plate a mercury film on a carbon electrode surface) presents a problem. The aim of this work was the development of mercury coated screen-printed electrodes previously prepared in the lab and ready to use in-field. Thus some commercially available polymers like Nafion®, Eastman Kodak AQ29®, and Methocel® were investigated as mercury entrapping systems for electrochemical stripping analysis of heavy metals. Screen-printed disposable cells with a silver pseudo-reference electrode, a graphite counter electrode, and a graphite working electrode were used. To modify the sensor, the polymer solution was cast onto the carbon working electrode surface. Detection limits of 0.8 and 1 μg/L were obtained for lead and cadmium respectively. Since Methocel® based electrodes showed the best performance, they were used for the analysis of real samples. The results were compared with those obtained using a classical thin mercury film electrode and ICP spectroscopy. All the experiments reported here were performed in un-deareated solutions as required for in-field analysis. 相似文献
6.
Veronika Pinkova Gajdosova Lenka Lorencova Anna Blsakova Peter Kasak Tomas Bertok Jan Tkac 《Current Opinion in Electrochemistry》2021
The review provides articles discussing big challenges behind successful design of impedimetric biosensors and the way such challenges were/could be addressed for highly sensitive affinity detection of proteins. In particular, the effect of gold etching by chloride ions or by CN? ions (released from the redox probe [Fe(CN)6]3-/4-), the effect of ionic strength of the assay buffer; the effect of initial interfacial properties (capacitance) and the effect of the high analyte:bioreceptor ratio on electrochemical impedance spectroscopy–based biosensing are discussed. The review provides also short discussion related to other factors, which can significantly affect operational performance of electrochemical impedance spectroscopy–based biosensing including novel conductive interfaces, small bioreceptors, strategies for improved selectivity (nonbiofouling interfaces) and sensitivity (use of nanoparticles). 相似文献
7.
Qun Wang Qiang Xue Tao Chen Jiawei Li Yuehua Liu Xiaohan Shan Fei Liu Jianbo Jia 《中国化学快报》2021,32(2):609-619
The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution,which in turn will affect human health.Therefore,it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields.Compared with traditional detection methods,electrochemical sensors have received extensive attention due to their advantages such as high sensitivity,low detection limit,and good selectivity.In this mini review,we summarized the latest developments and new trends in electrochemical sensors for antibiotics.Here,modification methods and materials of electrode are discussed.We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields.In addition,the existing problems and the future challenges ahead have been proposed.We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future. 相似文献
8.
本文提出了一种新的离子选择性电极分析方法,即等电位差-标准加入法。本方法已用于氟的测定。进行了理论数据验证及误差分析,标准溶液的回收率为96.6%-104.3%。本方法的影响因素少、准确度好、操作及计算简便。 相似文献
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10.
《Electroanalysis》2017,29(6):1635-1642
Our studies are focused on the development of novel potentiometric sensors for the quantification of the neurotransmitter serotonin. Therefore, ion‐selective electrodes based on plasticized PVC membranes are applied. The electroactive part of the membrane consists of an ion pair complex formed between the protonated analyte and a carborane anion [Co(1,2‐C2B9H11)2]−. The analytical performance of the electrode was studied regarding sensitivity, concentration range, limit of detection and potential stability. The ion‐selective electrodes were optimized with respect to the material of the transducing element, as well as the membrane thickness and its composition. Stable, all solid state ISEs could be developed, using the non‐polar plasticizer NPOE and a graphite rod with high surface area as transducing element. We thus achieved a near Nernstian response over three decades of concentration (2.25⋅10‐5‐1.00⋅10‐2 M) and a limit of detection in the μ‐molar range for the optimized electrodes. The electrodes could successfully be miniaturized using carbon based screen printed electrodes. 相似文献