The determination of copper,lead and cadmium in sea water by differential pulse anodic stripping voltammetry

The effect of various instrumental parameters is investigated and optimized conditions established. The results are in accordance with the theory of differential pulse anodic stripping voltammetry. Both a hanging mercury drop electrode, and a rotating glassy carbon electrode mercury plated in situ were used. The best detection limit is obtained with the mercury film electrode, but the hanging mercury drop electrode is more reproducible. The differential pulse stripping technique is compared to linear sweep stripping, and increased sensitivity and better peak separation is demonstrated for the former technique, particularly when a hanging mercury drop electrode is used. However, the differential pulse technique will also improve the detection limit for a mercury film electrode, if the electrode has a non-ideal response with a corresponding high background current.     

Electrochemical Oxidation of Sanguinarine and of Its Oxidation Products at a Glassy Carbon Electrode – Relevance to Intracellular Effects

The electrochemical behavior of sanguinarine, a quaternary benzophenanthridine glycoside alkaloid with antimicrobial, anti‐inflammatory, antioxidant and/or immune‐stimulatory activities, was studied at a glassy carbon electrode using cyclic, differential pulse, and square wave voltammetry. The oxidation of sanguinarine is a quasireversible, diffusion‐controlled process and occurred in a cascade mechanism with the formation of several oxidation products which adsorbed at the electrode surface. The oxidation of sanguinarine is pH dependent and involves the transfer of the same number of electrons and protons. The adsorbed sanguinarine oxidation products are reversibly oxidized at the glassy carbon electrode surface and their oxidation for a wide range of pHs was also studied by differential pulse and square wave voltammetry. A mechanism for the oxidation of sanguinarine at glassy carbon electrode is proposed.     

电活化玻碳电极差分脉冲溶出伏安法测定磺胺嘧啶

采用线性循环溶出伏安法和差分脉冲溶出伏安法对磺胺嘧啶在电活化玻碳电极上的电化学行为进行了研究。玻碳电极在PBS溶液中(pH 7.0),用恒电位法在1.7 V阳极氧化400 s,在B-R缓冲溶液中,磺胺嘧啶在1.02V(vs.Ag/AgCl)处有一良好的氧化峰,在0.02～0.25 V/s范围内,其氧化峰电流与扫描速率呈良好线性关系,表明电极过程为受吸附控制的不可逆过程。差分脉冲溶出伏安法的氧化峰电流(Ipa)与磺胺嘧啶浓度1×10-6～1×10-4mol/L范围内呈良好的线性关系(r=0.9977),检出限为8.7×10-7mol/L(S/N=3)。方法已用于分析磺胺嘧啶片剂的分析。     

头孢哌酮在玻碳电极上的电化学行为及检测方法

应用循环伏安法、线性扫描伏安法和微分脉冲伏安法研究头孢哌酮在玻碳电极上的电化学行为,建立了应用伏安法定量检测头孢哌酮的新方法。头孢哌酮的电极过程为受吸附控制的不可逆过程,电极反应转移电子数和转移质子数均为2。头孢哌酮在pH1.0的1mol/LH3PO4-NaOH介质中,在+0.13V(vs.Ag/AgCl)电位处产生一灵敏的氧化峰,应用微分脉冲伏安法进行测定,该峰电流值Ip与头孢哌酮质量浓度在5.05×10-7～1.01×10-4g/mL范围内有良好的线性关系(R=0.9996),检出限为4.95×10-9g/mL,样品测定平均加标回收率达99.50%,相对标准偏差(RSD)为3.17%。     

Electrochemical Determination of Dopamine Using a Poly(3,4-Ethylenedioxythiophene)-Reduced Graphene Oxide-Modified Glassy Carbon Electrode

Poly(3,4-ethylenedioxythiophene) was deposited on a reduced graphene oxide-decorated glassy carbon electrode through an electrochemical polymerization. The resulting glassy carbon electrode-reduced graphene oxide-poly(3,4-ethylenedioxythiophene) electrode was applied as an electrochemical biosensor for the determination of dopamine in the presence of ascorbic acid and uric acid. The material deposited on glassy carbon electrode was investigated in terms of morphology and structural analysis. The comparison of electrochemical behavior of the glassy carbon electrode-reduced graphene oxide-poly(3,4-ethylenedioxythiophene) electrode with the glassy carbon electrode-graphene oxide, glassy carbon electrode-reduced graphene oxide, and glassy carbon electrode-poly(3,4-ethylenedioxythiophene) electrodes exhibited high electrocatalytic activity for dopamine detection. Electrochemical kinetic parameters of glassy carbon electrode-reduced graphene oxide-poly(3,4-ethylenedioxythiophene), including the charge transfer coefficient α (0.49) and electron transfer rate constant k_s (1.04), were determined and discussed. The glassy carbon electrode-reduced graphene oxide-poly(3,4-ethylenedioxythiophene) electrode was studied for the determination of dopamine by differential pulse voltammetry and exhibited a linear range from 19.6 to 122.8?µM with a sensitivity of 3.27?µA?µM^?1?cm^?2 and a detection limit of 1.92?µM. The developed biosensor exhibited good selectivity toward dopamine with high reproducibility and stability.     

Study of a glassy carbon electrode in amperometric detection using d.c., normal and differential pulse techniques

The results of a comparative study on d.c., normal pulse and differential pulse techniques applied to anodic amperometric detection at a glassy carbon electrode in a voltammetric flow-through cell are presented. The important aspects examined are response time, linearity, limit of detection and selectivity. It is shown that the d.c. mode is the most favourable as long as no adsorption of oxidation products takes place. If strong adsorption occurs, normal pulse detection is recommended, although the limit of detection is somewhat larger.     

Polyfurfural-Electrochemically Reduced Graphene Oxide Modified Glassy Carbon Electrode for the Direct Determination of Nitrofurazone

An electrochemical sensor based on a polyfurfural-electrochemically reduced graphene oxide modified glassy carbon electrode has been developed for the sensitive and rapid determination of nitrofurazone. The morphologies and properties of the sensor were characterized by electrochemical impedance spectroscopy, scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry (DPV). In pH 7.0 Britton–Robinson buffer solution, the as-prepared polyfurfural-electrochemically reduced graphene oxide modified glassy carbon electrode shows excellent electrocatalytic performance for the electrochemical reduction of nitrofurazone, and the reduction peak current is about 9.45, 1.31, and 1.25 times higher than that of the bare glassy carbon electrode, polyfurfural modified glassy carbon electrode, and electrochemically reduced graphene oxide modified glassy carbon electrode, respectively. The DPV determination of nitrofurazone indicates that the linear range and detection limit of nitrofurazone are 1–50 and 0.25?µmol/dm³, respectively. In addition, this sensor exhibits high selectivity, reproducibility, stability, and also was successfully used to directly determine nitrofurazone in the commercial antibacterial lotion with comparative sensitivity to high-performance liquid chromatography, showing its promising application prospects.     

An electroanalytical study of the anticancer drug dacarbazine

The electrochemical behaviour of dacarbazine [5-(3,3-dimethyl-1-triazenyl) imidazole-4-carboxamide; DTIC] was investigated by Tast and differential pulse polarography (d.p.p.) at the dropping mercury electrode, by cyclic and differential pulse voltammetry at the hanging mercury drop electrode and by anodic voltammetry at the glassy carbon electrode. Calibration graphs were obtained for 2×10^?8?2×10^?5 M DTIC by d.p.p., for 5×10^?9?1×10^?5 M by adsorptive stripping voltammetry ar a hanging mercury drop electrode, and for 1?10×10^?5 M by high-performance liquid chromatography with oxidative amperometric detection at a glassy carbon electrode. The methods are compared and applied to determine DTIC added to blood serum after a simple clean-up procedure.     

Voltammetric determination of cefpirome at multiwalled carbon nanotube modified glassy carbon sensor based electrode in bulk form and pharmaceutical formulation

A new, simple and low cost voltammetric method for the determination of cefpirome in pharmaceutical preparations has been developed using multiwalled carbon nanotube modified glassy carbon electrode (MWCNT), which showed stable response with enhanced selectivity and sensitivity over the bare glassy carbon electrode. A multiwalled carbon nanotube (MWCNT) modified glassy carbon electrode (GCE) is used for the simultaneous determination of cefpirome by differential pulse voltammetry and square wave voltammetry. Results indicated that cathodic peak of cefpirome is greatly improved at MWCNT modified GC electrode as compared with the bare GC electrode showing excellent electrocatalytic activity towards cefpirome reduction. Linear calibration curves are obtained over the concentration range 100-600 μg mL(-1) in Britton Robinson buffer at pH 4.51 with limit of detection (LOD) and limit of quantification (LOQ) are 0.647 μg mL(-1) and 2.159 μg mL(-1) using SWV and 5.540 μg mL(-1) and 18.489 μg mL(-1) using DPV, respectively. The described method is rapid and can be successfully applied for the determination of cefpirome in bulk form and pharmaceutical formulations.     

Anodic oxidation of etodolac and its square wave and differential pulse voltammetric determination in pharmaceuticals and human serum

A voltammetric study of the oxidation of etodolac has been carried out at the glassy carbon electrode. The electrochemical oxidation of etodolac was investigated by cyclic, linear sweep, differential pulse and square wave voltammetry using glassy carbon electrode. Different parameters were tested to optimize the conditions for the determination of etodolac. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton-Robinson buffer at pH 2.15 for differential pulse and square wave voltammetric techniques. The linear response was obtained in the ranges of 2.10(-6)-8.10(-5) M with a detection limit of 6.8x10(-7) and 6x10(-6)-8x10(-5) M with a detection limit of 1.1x10(-6) M for differential pulse and square wave voltammetric techniques, respectively. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of the etodolac in tablet dosage form and human serum.     

Electrochemical study of zolpidem at glassy carbon electrode and its determination in a tablet dosage form by differential pulse voltammetry

The oxidative behaviour of, a hypnotic drug, zolpidem was studied at glassy carbon electrode in Britton-Robinson buffer over the pH range 2.0-11.0 using cyclic, linear sweep and differential pulse voltammetry. Oxidation of the drug was effected in a single irreversible, diffusion-controlled step. Using differential pulse voltammetry (DPV), the drug yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 8.0 at +0.889 V (vs. Ag/AgCl) on glassy carbon electrode. This process could be used to determine zolpidem concentrations in the range 5.0 x 10(-7) M to 1.0 x 10(-5) M with a detection limit of 2.0 x 10(-7) M. The method was applied, without any interference from the excipients, to the determination of the drug in a tablet dosage form.     

Electrochemical behavior of uric acid and epinephrine at an electrochemically activated glassy carbon electrode

A pretreated glassy carbon electrode by electrochemical activation has been proposed for simultaneous investigation and determination of epinephrine and uric acid by differential pulse voltammetry. This pretreated glassy carbon electrode exhibits a potent and persistent electron-mediating behavior followed by well-separated oxidation peaks towards epinephrine and uric acid with a potential difference of 161 mV, which is large enough to determine epinephrine and uric acid individually and simultaneously. Under the optimum condition, the detection limit of epinephrine is 8.9 x 10(-8)mol L(-1) and that of uric acid is 1.6 x 10(-7)mol L(-1). The proposed method was successfully used for the determination of epinephrine and uric acid in real samples with satisfactory results.     

A Determination of 6-Mercaptopurine and 6-Thio-Guanine By Anodic Differential Pulse Voltammetry

Abstract

The anodic oxidation of 6-mercaptopurine and 6-thioguanine has been studied on a rotating and stationary disk electrode of glassy carbon, using d.c. and differential pulse potential program. Conditions have been found for determination of these substances by anodic differential pulse voltammetry on a rotating disk electrode, with a detection limit of about 2 × 10^?5 mol 1^?1.     

电活化玻碳电极差分脉冲伏安法测定水杨酸的研

采用循环伏安法和差分脉冲伏安法对水杨酸在电活化玻碳电极上的电化学行为进行研究.在pH7.0的PBS溶液中,将玻碳电极用恒电位法在+1.7V电位阳极氧化400 s.在0.2 mol·L- NaOH溶液中,水杨酸在0.602 V处有一良好的氧化峰,其氧化峰电流与扫描速率在0.02～0.2 V·s-1范围内呈良好线性关系,表...     

多巴胺在聚亚甲基蓝/石墨烯修饰电极上的电化学行为研究

利用电聚合方法在石墨烯修饰的玻碳电极表面制备了聚亚甲基蓝/石墨烯修饰电极(PMB/GH/GCE)。采用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了多巴胺(DA)和抗坏血酸(AA)在该修饰电极上的电化学行为。在pH 6.9的磷酸盐缓冲溶液中,DA和AA分别在0.208 V和-0.108 V处产生灵敏的氧化峰,与其在聚亚甲基蓝和石墨烯单层修饰电极上的电化学行为相比,两者的峰电流明显增加,峰电位差达316 mV。研究表明,电聚合方法使亚甲基蓝牢固地非共价修饰到石墨烯上,并产生协同增效作用,较好地提高了电极的灵敏度和分子识别性能,有利于在大量AA存在下实现对DA的选择性测定。在1.00×10-3mol/L AA的存在下,DA的差分脉冲伏安法峰电流与其浓度在1.00×10-7～5.00×10-3mol/L范围内呈良好的线性关系,检出限达1.00×10-8mol/L。将该方法用于盐酸多巴胺注射液的测定,结果满意。     

Determination of Melphalan Using Differential Pulse Voltammetry

Abstract

The anodic oxidation of melphalan was studied on a glassy carbon disk electrode, either stationary or rotated, using a d.c. and a differential pulse potential program. The conditions have been found for a differential pulse voltammetric determination of the substance, with a detection limit of 1 × 10^?6 mol 1^?1     

石墨烯修饰玻碳电极测定邻苯二酚

制备了用于测定邻苯二酚(CAT)的石墨烯修饰电极,并应用循环伏安法研究了CAT在该修饰电极上的电化学行为;用差分脉冲伏安法研究了测试底液的pH值对该修饰电极性能的影响,结果表明,此修饰电极在含不同浓度CAT的PBS溶液(pH=7.0)中测定,响应电流与CAT浓度在5.0×10-8～5.6×10-4mol/L范围内有良好的线性关系,相关系数r=0.9919,检出限为6.68×10-9mol/L(S/N=3)。与其它几种修饰电极相比,石墨烯修饰电极制备简单、响应时间快、操作简便,稳定性和重现性良好,有应用价值。     

银纳米颗粒的合成及用于抗癌药氟他胺的电化学检测（英文）

Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+ at an open circuit potential followed by the electrochemical reduction of the Ag+.The presence of the calixarene layer on the electrode surface controlled the particle size and prevented agglomeration.Cyclic voltam‐metry showed that the Ag nanoparticles on the modified glassy carbon electrode had good catalytic ability for the reduction of flutamide.The effects of calixarene concentration,potential applied for the reduction of Ag+,number of calixarene layers,and p H value on the electrocatalytic activity of the Ag nanoparticles were investigated.The modified electrode had a linear range in differential pulse voltammetry of 10-1000 μmol/L with a detection limit of 9.33 μmol/L for flutamide at an S/N = 3.The method was applied to the detection of flutamide in practical samples.     

Electrochemical Oxidation of Berberine and of Its Oxidation Products at a Glassy Carbon Electrode

The electrochemical behavior of berberine, an isoquinoline plant alkaloid with a wide spectrum of physiological effects, was studied at a glassy carbon electrode using cyclic, differential pulse and square‐wave voltammetry. The oxidation of berberine is a quasireversible, diffusion‐controlled process and occurred in a cascade mechanism with the formation of several oxidation products. The diffusion coefficient of berberine was calculated from cyclic voltammetry studies to be D=1.69×10^?6 cm² s^?1. The oxidation process of berberine is also pH dependent and the number of electrons and protons transferred was determined using differential pulse voltammetry. The formation of several oxidation products that adsorbed at the glassy carbon electrode surface was observed and their electrochemical behavior characterized. A mechanism for the oxidation of berberine at a glassy carbon electrode was proposed.     

芦丁在铂纳米/碳纳米管修饰电极上电化学行为研究

通过电沉积的方式在多壁碳纳米管(MWCNTs)修饰玻碳电极表面上沉积铂(pt)纳米粒子,并运用循环伏安法(CV)、示差脉冲伏安法(DPV)探讨了芦丁在铂纳米/碳纳米管/玻碳电极上的电化学行为.实验结果表明,芦丁在该修饰电极上呈现一对良好氧化还原峰,其氧化峰电流与浓度在3.2×10(-8)～1.2×10(-5)mol/L...