银微盘电极上L-半胱氨酸的伏安行为研究

银微盘电极上Ｌ－半胱氨酸的伏安行为研究方宾,方惠群,陈洪渊（南京大学化学系,南京,２１００９３）关键词银微盘电极,Ｌ－半胱氨酸,循环伏安法由碳纤维、金、铂、铱等材料制成微电极的研究国内、外报道甚多［１～５］,但以银为材料制成的电极在生化物质方面的研究...     

普鲁士蓝膜修饰电极循环伏安行为的研究

本文研究普鲁士蓝(PB)膜修饰电极的循环伏安行为,结果表明,膜中电活性中心间的相互作用导致PB膜电极的伏安行为偏离理想表面波.用有限扩散边界模型解释了高电位扫速下膜电极的伏安行为.在含钾离子的电解质溶液中测得PB膜中电荷传输扩散系数为10~(-9)～10~(-11)cm~2/s.     

Studies on the Electrochemical Properties of Amphiphilic Ferrocenylimines Compounds

A series of amphiphilic ferrocenylimine compounds (four amphiphilic ferrocenylimines and four corresponding palladium complexes) were synthesized and their electrochemical characters were also investigated in detail. The results revealed that the redox of ferrocene derivatives was assumed by the ferrocene group and affected by substituent groups. Some effect rules were discovered and are described here. Moreover, the dynamics parameters of the electrode process were detected by several electrochemistry techniques.     

Disposable Injection‐Moulded Cell‐on‐a‐Chip Microfluidic Devices with Integrated Conducting Polymer Electrodes for On‐Line Voltammetric and Electrochemiluminescence Detection

This work reports the construction and characterization of plastic electrochemical micro‐flow‐cells with integrated injection‐moulded polymer electrodes. The three electrodes (working, auxiliary, and reference) were fabricated by injection‐moulding from a conducting grade of polystyrene loaded with carbon fibers. On‐chip reference electrodes were prepared by coating one of the conducting polymer electrodes with a Ag/AgCl layer (implemented either by e‐beam evaporation of Ag followed by electrochemical formation of AgCl or by applying a Ag/AgCl paste). Working electrodes were either polymer electrodes coated with Au by e‐beam evaporation or bare conducting polymer electrodes. The electrodes were integrated into the micro‐flow‐cells by an over‐moulding process followed by ultrasonic welding. The devices were characterized by optical and electrochemical techniques. Studies by cyclic voltammetry (CV), anodic stripping voltammetry (ASV) and electrochemiluminescence (ECL) demonstrate ‘proof–of‐principle’ of the micro‐flow‐cells as electrochemical sensors.     

Study on the Voltammetric Behaviour of Emulsifier OP across the Water-nitrobenzene Interface and its Application

Surfactantsareproducedworldwideinlargeamountsandwidelyusedinhouseholdorindustrialcleaners,cosmetic,researchlaboratories,etc.Manyelectfoanalyticalmethodsdevotedtosurfactantanalysishavebeenproposed',suchaspotentiometry,amperometry,tensammetry,electrocaPillarymeasurements.InthispaPer,emulsifierOP,asanewionophore,hasbeenintroducedtofacilitatemetaliontransferacrossaliquid/liquidinterface.ThevoltammetricbehaviourofemulsifierOP(EOP)whichfacilitatesthetransferofNa acrossthewater/nitrobebzene(w/nb)…     

1,4—二氢吡啶及其衍生物电化学反应机理的研究

研究了１１种１，４－二氢吡啶及其衍生物在乙腈溶剂中和铂盘电极上的电化学行为。实验结果表明：１，４－二氢吡啶及其衍生物在铂盘电极上的反应是受扩散和化学反应速率控制的两电子不可逆氧化过程，经连续两步失电子脱氢后形成相应的吡啶。用紫外吸收光谱电化学方法观测了电化学氧化过程。并与化学氧化产物的紫外光谱作了比较，证明１，４－二氢吡啶的电化学氧化产物与化学氧化产物一致。因此，电化学氧化是一种不需加化学试剂可使     

Electrochemical Studies of Three Dimensional Graphene Foam as an Electrode Material

Graphene foam is one kind of network of three dimensional (3D) graphene, which inherits the properties of two dimensional graphene and overcomes the aggregation/stacking of graphene sheets. In this work, graphene foam has been characterized by scanning electron microscopy and Raman spectroscopy. A graphene foam electrode was evaluated as a new electrode material by cyclic voltammetry (CV) and used for the detection of trace level of Pb²⁺ by anodic stripping voltammetry (ASV). Under the optimized condition of deposition potential (‐1.2 V) and deposition time (2 min), the detection limit is estimated to be 40 nM for Pb²⁺ based on the 3σ method.     

Voltammetric Measurement of [Cu(II)]/[Cu(I)] at a Platinum Rotating Disc Electrode and Control by Electrolysis at a Platinum Net Electrode in Chloride Solutions

ABSTRACT

A method has been described to measure and control the [Cu(II)]/[Cu(I)] bulk concentration ratio in aqueous chloride solutions. A variation of the ratio is achieved by controlled potential electrolysis at appropriate reducing or oxidizing potentials. The concentration ratio can be monitored by a repetitive double potential step amperometric method at a platinum rotating disc electrode. The amperometric signal can be used to control the electrolytic process in order to obtain and maintain a predetermined bulk concentration ratio. Diffusion coefficients of respectively 6.2 10^?6 and 5.6 10^?6 cm² s^?1 have been determined for Cu(II) and Cu(I). Potential applications of the method are the control of polymerisation reactions, of the reduction of textile dyes with the aid of a mediator system and of the colour characteristics of different kinds of glass.     

镀锡电解液中有机添加剂的电化学氧化

应用循环伏安法(CV)研究镀锡液有机添加剂PSA(苯酚磺酸)、EN(α-萘酚聚氧乙烯醚)和ENSA(α-萘酚磺酸聚氧乙烯醚)的阳极伏安行为.实验证明,PSA溶液在1.2 V附近产生一个阳极氧化峰,EN和ENSA溶液在0.95 V和1.3 V都出现阳极氧化峰.恒电流电解后用HPLC(高效液相色谱)和EI/MS(电子轰击质谱)分析该有机添加剂的阳极氧化产物,讨论其相关的电化学反应机理.     

Abrasive Stripping Voltammetric Studies of Lignin and Lignin Model Compounds

Lignin is potentially a major renewable, nonfossil source of aromatic and cyclohexyl compounds. In this study, we have investigated the abrasive stripping voltammetry of lignin and four lignin model compounds in the room temperature ionic liquids (RTILs) [C₄mim][NTf₂], [N_6,2,2,2][NTf₂] and [C₄mim][OTf] (where [C₄mim]⁺=1‐butyl‐3‐methylimidazolium, [N_6,2,2,2]⁺=n‐hexyltriethylammonium, [NTf₂]^?=bis(trifluoromethanesulfonyl)imide and [OTf]^? =trifluoromethanesulfonate) on a gold macrodisk and in 0.1 M H₂SO₄ and 0.1 M NaOH on a boron‐doped diamond (BDD) macroelectrode, with the hope of using the voltammetry to fingerprint the functional groups within the lignin molecule. The use of RTILs on metal electrodes, or either acidic or basic media in combination with BDD electrodes allows solvent systems with wide electrochemical potential windows, useful for studying voltammetry which may be difficult to observe in systems where early breakdown of the solvent occurs.     

Voltammetric Oxidation of Ambroxol and Application to Its Determination in Pharmaceuticals and in Drug Dissolution Studies

A detailed study of the electrochemistry of ambroxol at a glassy carbon electrode was carried out in the pH range 1.8–11.0 in aqueous solution using cyclic and differential pulse voltammetry. The compound was oxidized irreversibly at high positive potentials resulting in the formation of a chemical product at less positive potentials, which was more readily oxidized than the parent compound. In addition, a differential pulse voltammetric method was proposed for the determination of the drug in different pharmaceutical formulations, and in drug dissolution studies.     

Spectroelectrochemical and Voltammetric Studies of L‐DOPA

The electrooxidation of L -dopa at GC electrode was studied by in situ UV-vis spectroelectrochemistry (SEC) and cyclic voltammetry. The mechanism of electrooxidation and some reaction parameters were obtained. The results showed that the whole electrooxidation reaction of L -dopa at glassy carbon (GC) electrode was an irreversible electrochemical process followed by a chemical reaction in neutral solution (EC mechanism). The spectroelectrochemical data were treated by the double logarithm method together with nonlinear regression, from which the formal potential E⁰=228 mV, the apparent electron-transfer number of the electrooxidation reaction αn=0.376 (R=0.99, SD=0.26), the standard electrochemical rate constant k⁰=(3.93±0.12)×10⁻4 cm s⁻¹ (SD=1.02×10⁻²), and the formation equilibrium constant of the following chemical reaction k_c=(5.38±0.34)×10⁻¹ s⁻¹ (SD=1.02×10⁻²) were also obtained.     

羟乙芦丁在玻碳电极上的阳极微分脉冲伏安法测定

本文对羟乙芦丁在玻碳电极上的阳极微分脉冲安行为进行了研究，发现在Ｎａ２ＨＰＯ４溶液中（ｐＨ＝８．９５）于＋０．６４Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）左右产生一个良好的阳极氧化伏安峰，浓度在５～６０ｍｇ／Ｌ之间与峰电流呈线性关系，不需分离直接测定了片剂中的羟乙芦丁含量。电极反应为扩散速率控制的不可逆可程。     

铂/多壁碳纳米管修饰玻碳电极用于微分脉冲伏安法测定左旋多巴

采用微波辅助加热多元醇技术制备了载铂多壁碳纳米管复合材料,并将该复合材料分散在N,N′-二甲基甲酰胺溶液中得到悬浮液,取14μL悬浮液滴涂在玻碳电极表面,制备铂/多壁碳纳米管修饰电极(Pt/MWCNT′s/GCE)。循环伏安法研究了在0.05mol·L~(-1)硫酸支持电解质中,在0.30～0.70V(vs.SCE)电位范围内,左旋多巴在修饰电极上的电化学行为,结果表明:左旋多巴在Pt/MWCNT′s/GCE上于电位0.548V处可见明显的氧化峰,且氧化峰电流显著高于在MWCNT′s/GCE和裸玻碳电极上的氧化峰电流。提出了用微分脉冲伏安法测定左旋多巴的方法。左旋多巴的浓度在8.0×10~(-6)～2.0×10~(-1)mol·L~(-1)范围内与其氧化峰电流呈线性关系,检出限(3S/N)为1.9×10~(-6)mol·L~(-1),平均回收率为102.8%。     

碳糊电极阳极溶出法测定单宁酸的研究

用碳糊电极阳极溶出法研究了单宁酸的测定方法。实验表明,在1.0 mol/LHCl介质中,富集120 s,单宁酸在0.65 V(vs.SCE)处出现阳极溶出峰,在5.0×10-7~6.0×10-5mol/L范围内,其峰电流的大小与单宁酸的浓度呈线性关系,相关系数为0.9991,检出限为1.0×10-7mol/L。该法灵敏度较高,操作简便,可用于啤酒中单宁酸的测定,平均回收率为99.8%。     

取代苯甲醛肟和取代苯乙酮肟电化学氧化机理的研究

研究了１０种取代苯甲醛肟和５种取代苯乙酮肟的电化学氧化机理。这二类肟的氧化电位随取代基吸电子能力的增大而增高，并与它们相应的Ｈａｍｍｅｔｔ常数有线性关系。它们在电化学氧化过程中均有ｉｍｉｎｏｘｙ自由基生成，但最后产物各不相同。用控制电位电解和紫外吸收光谱检法验证了部分电化学氧化产物。因此，电化学氧化法可作为由肟类产生ｉｍｉｎｏｘｙ自由基的一种方法。     

Comparison of the Effects of Biofouling on Voltammetric and Potentiometric Measurements

Biofouling of sensors is a common problem when measuring biological samples. The adherence of proteins and biomolecules, called hemostasis, is the first of four steps that lead to biofouling and eventually a foreign body response. This typically occurs within the first hours after the exposure of the biosensor to a biological sample. The purpose of this study was to assess the effect of this initial step of biofouling on cyclic voltammetry and potentiometric measurements. The results show that biofouling occurred rapidly within minutes and strongly affected cyclic voltammetry measurements, while potentiometric measurements were minimally affected even after 24 hours.     

磷酸可待因在Nafion修饰玻碳电极上的伏安行为研究及测定

用循环伏安法和微分脉冲吸附伏安法对磷酸可待因在Nafion修饰玻碳电极上的伏安行为进行了研究。结果表明在 0 .1mol/LHCl底液中 ,磷酸可待因在 + 1 .0 6V处 (vs.SCE)产生一良好的氧化峰 ,磷酸可待因浓度在 5 .0× 1 0 - 7～2 .5× 1 0 - 5mol/L范围内与峰电流呈线性关系 ,检出限为 1 .3× 1 0 - 7mol/L。并分别对其单方药和复方药制剂进行了测定     

Electrochemical Oxidation of Donepezil and Its Voltammetric Determination at Gold Electrode

The oxidative ability of donepezil, a frequently prescribed drug for the treatment of Alzheimer’s disease is reported for the first time at a gold electrode. It was oxidized by cyclic voltammetry and determined by square wave voltammetry in phosphate buffer electrolyte. Electrochemical degradation of donepezil was carried out by long term potential cycling. The identification and characterization of the major product, isolated by preparative high performance liquid chromatography, was performed by high resolution mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy. Donepezil hydroxy derivative was identified as the major electrochemical oxidation product from donepezil.     

Effects of Electroplating Variables on the Voltammetric Properties of Bismuth Deposits Plated Potentiostatically

An attempt is made to describe the electrochemical properties of bismuth films, plated in‐situ on glassy carbon in acetic buffer, over a broad range of deposition potentials. It is shown that accumulation during anodic stripping voltammetric determination of lead and zinc at the bismuth film electrode depends to a large extent on the electrolyte composition and the plating parameters. The influence of the plating potential on Pb deposition is moderate, but it could not be disregarded during Zn quantification. The sources of electrode poisoning effects are discussed in detail. Voltammetric studies are complemented by AFM microscopic observations.