Preconcentration and voltammetric determination of trace myoglobin at a 6-mercaptopurine modified silver electrode

6-Mercaptopurine(6-MP) is covalently modified onto a silver electrode to construct a chemically modified electrode (CME). It exhibits the capability of selectively complexing myoglobin and can be applied as a selective biosensor for this compound. Myoglobin is accumulated onto the CME at 0.32 V (vs. SCE); after exchanging the medium it is determined by differential pulse stripping voltammetry. A cathodic stripping peak is obtained at 0.15 V (vs. SCE) by scanning the potential from 0.35 to –0.1 V. The peak currents are linearly proportional to the concentration of myoglobin in the range of 0.2 ∼ 4 μg/mL with a relative standard deviation of 7.8%. The detection limit is about 0.1 μg/mL. The mechanism of the complexation is also discussed. Received: 30 January 1997 / Revised: 7 May 1996 / Accepted: 10 May 1996     

Automated determination of molybdenum(VI) in seawater by means of constant-current reduction of the adsorbed 8-quinolinol complex in a computerized flow potentiometric stripping analyzer

Molybdenum(VI) in seawater is determined by means of potentiostatic adsorption of the 8-quinolinol complex onto a mercury film electrode at ?0.2 V vs. SCE and subsequent reduction of the complex by means of constant-current stripping in 5 M calcium chloride medium with a fully automated stripping analyzer. A single stripping peak at –0.42 V vs. SCE was obtained. The molybdenum(VI) concentration in reference seawater NASS-1, with a certified value of 11.5 ± 1.9 μg 1^?1, was found to be 8.9 ± 1.3 μg 1^?1 (n = 10).     

痕量铅在草酸修饰电极上阳极溶出伏安的研究

本文对草酸修饰电极的制作、痕量铅在草酸修饰电极上的反应机理和电化学特性作了研究。采用阳极溶出伏安法,测定铅的灵敏度比玻碳电极提高7.5倍,在1.0～15.0ng·/mL铅浓度范围内溶出峰高与铅浓度呈良好的线性关系。连续测定12次变异系数为3.0％。利用草酸修饰电极对人尿中痕量铅进行了测定,结果良好。     

Electrode Modified with Langmuir–Blodgett (LB) Film of Calixarenes for Preconcentration and Stripping Analysis of Hg(II)

A new type of current sensor, Langmuir–Blodgett (LB) film of calixarene on the surface of glassy carbon electrode (GCE) was prepared for determination of mercury by anodic stripping voltammetry (ASV). An anodic stripping peak was obtained at 0.15 V (vs. SCE) by scanning the potential from ?0.6 to +0.6 V. Compared with a bare GCE, the LB film coated electrode greatly improves the sensitivity of measuring mercury ion. The fabricated electrode in a 0.1 M H₂SO₄+0.01 M HCl solution shows a linear voltammetric response in the range of 0.07–40 μg L^?1 and detection limit of 0.04 μg L^?1 (ca. 2×10^?10 M). The high sensitivity, selectivity, and stability of this LB film modified electrode demonstrates its practical application for a simple, rapid and economical determination of Hg²⁺ in a water sample.     

芦荟大黄素1.5阶微分阳极溶出伏安法测定及电化学性质研究

研究了芦荟大黄素在以 0 .1mol/LHAc (pH 2 .89)为支持电解质 ,玻碳电极为工作电极的吸附伏安行为 .结果表明芦荟大黄素存在一个准可逆的双电子转移过程 ,其峰电流Ip 和峰电位Ep 与溶液 pH值有关 .同时还建立了用 1.5阶微分阳极溶出伏安法测定含量的新方法 .在 - 0 .80V(vs.SCE)电位下富集 ,可得一灵敏的微分阳极溶出峰 ,峰电位Ep 为 - 0 .38V ,峰电流Ip 与芦荟大黄素的浓度在 2 .0× 10 - 7～ 8.0× 10 - 6 mol/L范围内成线性关系 ,最低检出限为 1.0× 10 - 7mol/L .该法用于含有芦荟大黄素体系的测定 ,具有简便、快速、准确等优点     

Determination of Sulpiride by Linear Sweep Stripping Voltammetry at a Mercury Electrode

This paper reports the electrochemical properties of sulpiride at a mercury electrode,especially its adsorptive characteristic,Sulpiride dissolved in a supporting electrolyte of a McIlvaine buffer at pH 6.8 represents a sensitive and well defined reduction wave by linear sweep stripping voltammetry.This method is based on the pre-concentration and the reduction of sulpiride at a hung mercury drop electrode.The reduction peak potential is -1.72V(vs.Ag-AgCl) and the peak current is proportional to the concentration of sulpiride in the range of 0.1-0.6 μg/mL.The detection limit is 0.0250μg/mL obtained under the experimental conditions selected in this work.The electrochemical properties of this system were investigated.and the proposed method was applied to the determination of sulpiride in pharmaceutical tablets with satisfactory results,It was compared well with the UV spectrophotometric method,showing a superior sensitivity.     

生物分子电催化的研究(Ⅲ)——血红蛋白在甲酚固紫修饰碳糊电极上的电催化

血红蛋白是脊椎动物红细胞内的呼吸蛋白,但由于其电活性中心不容易暴露以及在电极表面强烈吸附造成电极的钝化,使得它在一般固体电极上的电子传递速率很慢,得不到有效的电流响应。有关血红蛋白在固体电极上的电化学行为的研究很少。众多的分析化学家都在积极寻求加速血红蛋白电子传递速度的途径,使蛋白质直接电化学分析成为可能。最近的研究表明,某些染料修饰电极可以促进血红蛋白的电极过程,从而获得有效的电流响     

Adsorptive Stripping Voltammetric Detection of Single‐Stranded DNA at Electrochemically Modified Glassy Carbon Electrode

Electrochemically modified glassy carbon electrode (GCE) was used to study the electrochemical oxidation and detection of denatured single‐stranded (ss) DNA by means of adsorptive stripping voltammetry. The modification of GCE, by electrochemical oxidation at +1.75 V (vs.SCE) for 10 min and cyclic sweep between +0.3 V and ?1.3 V for 20 cycles in pH 5.0 phosphate buffer, results in 100‐fold improvement in sensitivity for ssDNA detection. We speculated that the modified GCE has a high affinity to single‐stranded DNA through hydrogen bond (specific static adsorption). Single‐stranded DNA can accumulate at the GCE surface at open circuit and produce a well‐defined oxidation peak corresponding to the guanine residues at about +0.80 V in pH 5.0 phosphate buffer, while the native DNA gives no signal under the same condition. The peak currents are proportional to the ssDNA concentration in the range of 0–18.0 μg mL^?1. The detection limit of denatured ssDNA is ca. 0.2 μg mL^?1 when the accumulation time is 8 min at open circuit. The accumulation mechanism of ssDNA on the modified GCE was discussed.     

茜素修饰碳糊电极吸附伏安法测定痕量铜

报道了采用茜素修饰碳糊电极测定痕量铜的阳极溶出伏安法。在浓度为0 .1 mol/L 的 HAc- Na Ac缓冲溶液 (p H4.5)中 ,于 +0 .1 0 V处富集 ,- 0 .30 V还原后再进行阳极化扫描 ,于 - 0 .0 5V处获得一灵敏的铜的溶出峰 ,二次导数峰电流与铜浓度在 1 .6× 1 0 -9mol/L～ 4.7× 1 0 -7mol/L范围内呈线性关系 ,检出限达 8.0× 1 0 -10 mol/L。同时 ,对电极反应机理进行了讨论。方法应用于锌合金中铜的测定。     

Studies on the voltammetric behaviour of a 2-mercaptoimidazole containing carbon paste electrode: determination of traces of silver

The voltammetric behaviour of a 2-mercaptoimidazole (2-MI) containing carbon paste electrode was studied. When mixed to carbon paste as an electrode modifier, 2-MI can be reduced at negative potentials (–1 V vs. SCE), but it does not give a response in the potential range where Ag(0) is oxidized to Ag(I). Silver could be accumulated from 0.1 mol l^–1 acetate buffer onto a 2-MI modified carbon paste electrode without a potential applied; after medium exchange, it was reduced at –1 V vs. SCE in 0.1 mol l^–1 acetate buffer solution and determined by differential pulse anodic stripping voltammetry. With suitable preconcentration times, the detection limit was 0.1 g l^–1; a linear relation between current and concentration was found to exist within a range of 0.5 to 1000 g l^–1. In the presence of EDTA, common metal ions have no or only little effect on the voltammetric determination of silver.     

甲基对硫磷在聚噻吩/纳米二氧化钛修饰玻碳电极上的电化学行为及其测定

用循环伏安法(CV)、线性扫描溶出伏安法(LSSV)研究了甲基对硫磷(MPT)在聚噻吩/纳米二氧化钛修饰玻碳电极(PTh-NTiO2/GCE)上的电化学行为.实验表明,该修饰电极能显著提高MPT的氧化还原峰电流,在B-R缓冲溶液(pH 5.72)中,于-0.662V( vs.SCE)处产生灵敏的不可逆还原峰,其峰电流与...     

多壁碳纳米管修饰乙炔炭黑微电极测定碘

以多壁碳纳米管修饰乙炔炭黑微电极为工作电极,研究了碘离子在该修饰电极上的阳极溶出伏安特性。在0.1 mol/L KH2PO4 缓冲液(pH4.0)中,从200 mV以200 mV/s的速率正向扫描至1200 mV,碘离子在570 mV处出现一灵敏的阳极溶出峰。峰电流与碘离子的浓度在2.0×10-6～1.0×10-3 mol/L范围内呈良好的线性关系,检出限为8.0×10-7 mol/L。方法用于食盐中碘含量的测定,结果满意。     

天青I修饰电极的电化学性质及对血红蛋白的电催化还原

天青I修饰电极在pH=5.5的HAc-NaAc缓冲溶液中,在0.3～-0.7V电位范围内表现出可逆的氧化还原行为,其表面式量电位E^0'=-0.21V,表观电极反应速率常数k_s'=0.69s^-1,该电极对血红蛋白的还原过程具有良好的催化作用。实验结果表明,由电沉积构成的修饰电极较吸附法制备的修饰电极具有更好的稳定性。     

Nafion‐Modified Glassy Carbon Electrode for Trace Determination of Indium

Abstract

A new method for determination of trace indium is proposed by the adsorption stripping voltammetry (ASV) using a Nafion‐modified glassy carbon electrode (NMGCE). This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed, and the anodic peak potential is ca. ?0.548 V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of indium in water samples. There is a good linear relationship between the peak current (i_p) and indium(III) concentration in the range of 1.0×10^?9–1.0×10^?7 mol/l, and the limit of detection is 7.5×10^?10 mol/l.     

甲苯胺蓝修饰石墨电极的电化学性质及对血红蛋白的电催化还原

本文将电子媒体甲苯胺蓝吸附在石墨电极上制备成修饰电极。在＋０．２～０．５Ｖ（ｖｓ．ＳＣＥ）范围内，吸附态的甲苯胺蓝呈现有两质子参与的可逆性两电子氧化还原行为，在ｐＨ５．５醋酸盐缓冲溶液中，其表面式量电位Ｅ＾０为－０．２２Ｖ，表观表面电子传递速率常数ｋ为１．１Ｓ＾－１，甲苯胺蓝修饰电极具有良好的稳定性，它能加速血红蛋白在固体电极上的电子传递，产生很好的电流响应。     

Voltammetric Determination of L‐Dopa Using a Carbon Nanotubes‐Nafion Modified Glassy Carbon Electrode

Abstract

A method for determination of L‐dopa by the adsorption stripping voltammetry (ASV) using a multiwalled carbon nanotubes (MWNTs)–Nafion modified glassy carbon electrode (GMGCE) was proposed. This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed and the anodic peak potential is ca. 0.374V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of L‐dopa in samples. There is a good linear relationship between the peak current (i_p) and L‐dopa concentration in the range of 3.5×10^?7～1.5×10^?5 mol/L, with the limit of detection 5.0×10^?8 mol/L.     

碳糊电极阴极溶出伏安法测定当归中阿魏酸

采用碳糊电极作工作电极,阴极溶出伏安法对阿魏酸进行测定。在0.05mol.L-1盐酸溶液中,当有0.04mmol.L-1氯化钠溶液,0.004g.L-1十二烷基硫酸钠溶液存在时,1.1V(vs.SCE)富集180s,以100mV.s-1扫描速率从1.0V扫描至0V。阿魏酸在碳糊电极上于0.46V处产生一灵敏的阴极溶出伏安峰,峰电流与阿魏酸浓度在2.2×10-7～1.1×10-5 mol.L-1范围内呈线性关系,检出限(3S/N)为4.0×10-8 mol.L-1。初步探讨了阿魏酸的电化学性质,此方法用于测定当归中阿魏酸的含量,并以此样品为基体做回收试验,测得回收率在104.0%～109.1%之间,测定值的相对标准偏差(n=6)在2.6%～5.3%之间。     

Sensitive Voltammetric Determination of Cadmium(II) with 8‐Hydroxyquinoline and Ionic Liquid Modified Carbon Paste Electrode

In this paper 8‐hydroxyquinoline (HQ) and ionic liquid (IL) modified carbon paste electrode was fabricated and used for the sensitive determination of cadmium(II) with differential pulse anodic stripping voltammetry (DPASV). The modified electrode was prepared by the addition of HQ and IL 1‐ethyl‐3‐methylimidazoliam ethylsulphate as the modifiers into the traditional carbon paste mixture. Cd(II) was preconcentrated and reduced on the surface of the modified electrode at the potential of ‐1.0 V (vs. SCE) by the co‐contributions from the formation of HQ‐Cd(II) complex and the accumulation effect of IL. Then the reduced Cd on the electrode surface was reoxidized by DPASV with a sensitive oxidation peak appeared at ‐0.79 V (vs. SCE). Under the optimal conditions the oxidation peak current was proportional to the Cd(II) concentration in the range from 0.03 to 2.0 mol/L with the detection limit as 5.0 nmol/L (3σ). The proposed method was successfully applied to the water samples detection with the recovery in the range from 95.6% to 96.6%.     

亚硒酸钠在L-半胱氨酸自组装类生物膜修饰电极上的电化学行为

利用L-半胱氨酸自组装膜修饰金电极(L-Cys,Au/SAMs), 在0.05mol/L H_2SO_4 底液中研究了 Na_2SeO_3 的电化学特性.在0.00～1.30 V (vs. SCE) 电位范围内对微量Na_2SeO_3进行循环伏安扫描,发现L-Cys, Au/SAMs修饰电极在峰电位0.89 V处有灵敏的Se的氧化溶出峰.通过比较裸金电极和修饰电极在Na_2SeO_3 溶液中的电化学特性发现,修饰电极通过巯基中的S与Na_2SeO_3发生氧化还原作用生成Se,且修饰电极对沉积在电极表面的Se的氧化过程具有催化作用.根据Na_2SeO_3在单分子膜上的电化学行为,提出了单分子膜中硫(Au-S)与Se(Ⅳ)作用生成Se的反应机理、Se电化学催化氧化机理及巯基化合物通过生成纳米硒生物吸收Se的类生物膜模型.     

Electrochemical and Spectroelectrochemical Studies on Pyridoxine Hydrochloride Using a Poly(methylene blue) Modified Electrode

The electrochemical redox processes of pyridoxine hydrochloride (VB₆) at a poly(methylene blue) film modified glass carbon electrode (PMBE) in a phosphate buffer solution (PBS, pH 8.0) were studied by cyclic voltammetry. The VB₆ electrode reaction with quasi‐reversible characteristics was diffusion‐controlled at low scan rates and adsorption‐controlled at high scan rates. The anodic peak current positive to 0.6 V (vs. SCE) was found to be proportional to the concentration of VB₆ in the range of 0.010 to 1.03 mg?mL^?1 with a detection limit of 1.34 μg mL^?1. Fluorescence and UV‐vis absorption spectroelectrochemical measurements suggest that the pyridine ring was not destroyed over the potential range from ?0.8 to 1 V (vs. SCE), and the electrocatalytic generation of pyridoxal was anodically started at 0.57 V.