Sensitive Flow-Injection Electrochemical Determination of Hydrogen Peroxide at a Palladium Nanoparticle-Modified Pencil Graphite Electrode

A novel flow-injection amperometric method was proposed for the sensitive and enzymeless determination of hydrogen peroxide based on its electrocatalytic reduction at a palladium nanoparticle-modified pretreated pencil graphite electrode in a laboratory-constructed electrochemical flow cell. Cyclic voltammograms of the unmodified and modified electrodes were recorded in pH 7.0 phosphate buffer containing 0.10 M KCl at a scan rate of 50?mV s^?1 for the investigation of electrocatalytic reduction of hydrogen peroxide at the palladium nanoparticle-modified pretreated pencil graphite electrode. Cyclic voltammograms of the pretreated pencil graphite electrode revealed an irreversible oxidation peak and a weak reduction peak of hydrogen peroxide at +1100?mV and –450?mV vs. an Ag/AgCl/KCl saturated reference electrode. However, the reduction of hydrogen peroxide was observed at –100?mV with an increase in current in the cyclic voltammograms of the palladium nanoparticle-modified pretreated pencil graphite electrode compared to the unmodified electrode. These results indicate that the palladium nanoparticle-modified pretreated pencil graphite electrode exhibits efficient electrocatalytic activity for the reduction of hydrogen peroxide. A linear concentration range was obtained between .01 and 10.0?mM hydrogen peroxide with a detection limit of 3.0 µM from flow injection amperometric current–time curves recorded in pH 7.0 phosphate buffer at –100?mV and a 2.0?mL min^?1 flow rate. The novelty of this work relies on its use of a laboratory-constructed flow cell constructed for the pencil graphite electrode using these inexpensive, disposable, and electrochemically reactive modified electrodes for the amperometric determination of hydrogen peroxide in a flow injection analysis system.     

基于普鲁士蓝/二氧化锰复合材料修饰电极上的无酶过氧化氢传感器

合成了一种普鲁士蓝/二氧化锰(PB/MnO2)复合材料。表征结果显示两者成功地复合在一起。电化学测试结果表明复合材料比单独的PB具有更好的电化学活性。由修饰玻碳电极(GCE)构建的传感器对过氧化氢(H2O2)的还原具有良好的稳定性、重现性和选择性。     

氧化锌修饰铅笔芯电极电致化学发光法测定苯酚的研究

采用滴涂法将氧化锌纳米颗粒滴涂在自制铅笔芯电极上制成氧化锌修饰铅笔芯电极,当以过硫酸根为共反应剂时,该修饰电极在氢氧化钠溶液中具有良好的电致化学发光(ECL)行为,对其发光机理进行了考察。基于苯酚对该修饰电极的ECL具有抑制作用,建立了一种测量苯酚的新方法,当苯酚浓度为2×10~(-8)~2×10~(-6)mol/L时,发光强度与苯酚浓度的对数呈线性关系,检出限为1×10~(-8)mol/L。该方法具有灵敏度高、方法简单、快速、稳定性好等优点,将其应用于工业废水中苯酚浓度的检测,回收率为96.5%~104.5%。     

Nickel and Tungsten Bimetallic Nanoparticles Modified Pencil Graphite Electrode: A High-performance Electrochemical Sensor for Detection of Endocrine Disruptor Bisphenol A

In this work, an economically viable, very low cost, indigenous, ubiquitously available electrochemical sensor based on bimetallic nickel and tungsten nanoparticles modified pencil graphite electrode (NiNP-WNP@PGE) was fabricated for the sensitive and selective detection of bisphenol A (BPA). The NiNP-WNP@PGE sensor was prepared by a facile electrochemical one step co-deposition method. The prepared nanocomposite was morphologically characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), electrochemically by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The proposed sensor displayed high electrocatalytic activity towards electro-oxidation of BPA with one irreversible peak. The fabricated sensor displayed a wide detection window between 0.025 μM and 250 μM with a limit of detection of 0.012 μM. PGE sensor was successfully engaged for the detection of BPA in bottled water, biological, and baby glass samples.     

Sensitive and Rapid Flow Injection Amperometric Hydrazine Sensor using an Electrodeposited Gold Nanoparticle Graphite Pencil Electrode

A gold (Au) nanoparticle-modified graphite pencil electrode was prepared by an electrodeposition procedure for the sensitive and rapid flow injection amperometric determination of hydrazine (N₂H₄). The electrodeposited Au nanoparticles on the pretreated graphite pencil electrode surface were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammograms showed that the Au nanoparticle-modified pretreated graphite pencil electrode exhibits excellent electrocatalytic activity toward oxidation of hydrazine because the highly irreversibly and broadly observed oxidation peak at +600?mV at the pretreated graphite pencil electrode shifted to ?167?mV at the Au nanoparticle pretreated graphite pencil electrode; in addition, a significant enhancement in the oxidation peak current was obtained. Thus, the flow-injection (FI) amperometric hydrazine sensor was constructed based on its electrocatalytic oxidation at the Au nanoparticle-modified pretreated graphite pencil electrode. The Au nanoparticle-modified pretreated graphite pencil electrode exhibits a linear calibration curve between the flow injection amperometric current and hydrazine concentration within the concentration range from 0.01 to 100?µM with a detection limit of 0.002?µM. The flow injection amperometric sensor has been successfully used for the determination of N₂H₄ in water samples with good accuracy and precision.     

Trace Level Determination of Hydrogen Peroxide at a Carbon Ceramic Electrode Modified with Copper Oxide Nanostructures

An electrochemical sensor was developed for determination of hydrogen peroxide based on nanocopper oxides modified carbon sol‐gel or carbon ceramic electrode (CCE). The modified electrode was prepared by electrodeposition of metallic copper on the CCE surface and derivatized in situ to copper oxides nanostructures and characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. The modified electrode responded linearly to the hydrogen peroxide (H₂O₂) concentration over the range 0.78–193.98 µmol L^?1 with a detection limit of 71 nmol L^?1 (S/N=3) and the sensitivity of 0.697 A mol^?1 L cm^?2. This electrode was used as selective amperometric sensor for determination of H₂O₂ contents in hair coloring creams.     

An Enzyme‐free H2O2 Sensor Based on Poly(2‐Aminophenylbenzimidazole)/Gold Nanoparticles Coated Pencil Graphite Electrode

A poly(2‐aminophenylbenzimidazole)/gold nanoparticles (P2AB/AuNPs) coated disposable pencil graphite electrode (PGE) was fabricated as an enzyme‐free sensor for the H₂O₂ determination. P2AB/AuNPs and P2AB were successfully synthesized electrochemically on PGE in acetonitrile for the first time. The coatings were characterized by scanning electron microscopy, X‐ray diffraction spectroscopy, Energy‐dispersive X‐ray spectroscopy, Surface‐enhanced Raman spectroscopy, and UV‐Vis spectroscopy. AuNPs interacted with P2AB as carrier enhances the electrocatalytic activity towards reduction of H₂O₂. The analytical performance was evaluated in a 100 mM phosphate buffer solution at pH 6.5 by amperometry. The steady state current vs. H₂O₂ concentration is linear in the range of 0.06 to 100 mM (R²=0.992) with a limit of detection 3.67×10^?5 M at ?0.8 V vs. SCE and no interference is caused by ascorbic acid, dopamine, uric acid, and glucose. The examination for the sensitive determination of H₂O₂ was conducted in commercially available hair oxidant solution. The results demonstrate that P2AB/AuNPs/PGE has potential applications as a sensing material for quantitative determination of H₂O₂.     

An Unmediated Hydrogen Peroxide Sensor Based on a Hemoglobin-sds Film Modified Electrode

ABSTRACT

An unmediated hydrogen peroxide sensor is designed in this paper by employing a hemoglobin-SDS film modified electrode. Hemoglobin exhibits direct (unmediated) electrochemistry at the modified electrode. The protein also shows elegant catalytic activity towards the electrochemical reduction of hydrogen peroxide. Consequently, a prototype hydrogen peroxide sensor is prepared. Under optimum conditions, this sensor provides a linear response over the hydrogen peroxide concentrations in the range of 1×10^-5～1×10^-4 mol/L. The detection limit was 2×10^-6 mol/L The relative standard deviation was 4.2% for 6 successive determinations of the hydrogen peroxide at 1×10^-5 mol/L. This configuration is shown to be sensitive, stable and easily fabricated. It might be useful in the biological and industrial fields.     

Flow Injection Determination of Hydrogen Peroxide Using a Carbon Paste Electrode Modified with a Manganese Dioxide Film

Abstract

A manganese dioxide film modified carbon paste electrode was developed for use as an amperometric sensor for the determination of hydrogen peroxide (H₂O₂) in ammoniacal aqueous solutions. The electrode showed a stable response towards H₂O₂ after electrochemical activation. Effects of flow rate, operating potential, concentration, injection volume and interferences were investigated. A linear response towards H₂O₂ from 5 μg.l^?1 to 450 mg.l^?1 and a detection limit (3 signal-to-noise ratio) of 4.7 μg.l^?1 was found. The method was employed for the determination of H₂O₂ in rain water samples.     

Ruthenium Oxide Hexacyanoferrate Modified Electrode for Hydrogen Peroxide Detection

A sensor for H₂O₂ amperometric detection based on a Prussian blue (PB) analogue was developed. The electrocatalytic process allows the determination of hydrogen peroxide at 0.0 V with a limit of detection of 1.3 μmol L^?1 in a flow injection analysis (FIA) configuration. Studies on the optimization of the FIA parameters were performed and under optimal FIA operational conditions the linear response of the method was extended up to 500 μmol L^?1 hydrogen peroxide with good stability. The possibility of using the developed sensor in medium containing sodium ions and the increased operational stability constitute advantages in comparison with PB‐based amperometric sensors. The usefulness of the methodology was demonstrated by addition‐recovery experiments with rainwater samples and values were in the 98.8 to 103% range.     

Disposable Pencil Graphite Electrode for Ciprofloxacin Determination in Pharmaceutical Formulations by Square Wave Voltammetry

In this work, a new electrochemical sensor based on pencil graphite with interesting features, such as low cost (US$ 0.01 per electrode), ease manufacture, and portability was developed. The sensor showed an adequate manufacturing reproducibility with RSD <5.3 %. Under this electrochemical platform, ciprofloxacin underwent an irreversible oxidation process at 1.03 V, characterized by the diffusion of electroactive species. A simple method by square wave voltammetry (SWV) has been optimized for the determination of ciprofloxacin in pharmaceutical formulations using a pencil graphite electrode (PGE). The method showed satisfactory analytical performance, with a wide linear range (12 to 55 μmol L⁻¹), low detection limit (5.6 μmol L⁻¹), adequate precision (RSD <3.2 %), and accuracy with an average recovery of (102±15)%. Samples of pharmaceutical formulations were evaluated, obtaining levels of ciprofloxacin close to those established by the manufacturers. In addition, the samples were analyzed by liquid chromatography and there was no significant difference between the methods at the 95 % confidence level. In this sense, the method developed proved to be reliable and promising for the quality control of pharmaceutical formulations.     

Enzyme Electrode Sensor for Hydrogen Peroxide

Abstract

An enzymatic sensor was constructed from an oxygen amperometric sensor on whose surface a dialysis membrane containing covalently bonded catalase was set. Immobilization of the enzyme on the dialysis membrane surface was achieved with 2,4-dichloro-6-methoxy-s-triazine, a derivative of cyanuric chloride, which unlike others of its monosubstituted derivatives ensures some advantages. The time of measurement is less than 12 sec, for the kinetic method of the initial slope and one minute for the steady-state method. The sensor responds linearly to hydrogen peroxide in the concentration range 10^?3 - 10^?5 moles/1. The utilization of this sensor in intermittent and continuous operation in a laboratory enzymatic minireactor is discussed.     

Cathodized Gold Nanoparticle‐Modified Graphite Pencil Electrode for Non‐Enzymatic Sensitive Voltammetric Detection of Glucose

A highly sensitive enzymeless electrochemical glucose sensor has been developed based on the simply prepared cathodized gold nanoparticle‐modified graphite pencil electrode (AuNP‐GPE). Cyclic voltammetry (CV) experiments show that AuNP‐GPE is able to oxidize glucose partially at low potential (around −0.27) whereas the bare GPE cannot oxidize glucose in the entire tested potential windows. Besides, fructose and sucrose cannot be oxidized at potential lower than +0.1 V at AuNP‐GPE. As a result, the glucose oxidation peak at around −0.27 V is suitable enough for selective detection of glucose in the presence of fructose and sucrose. Cathodization of AuNP‐GPE under optimum condition (‐1.0 V for 30 s) in the same glucose solution before voltammetric measurement enhanced glucose oxidation peak current around −0.27 V to achieve an efficient electrochemical sensor for glucose with a detection limit of 12 μM and dynamic range between 0.05 to 5.0 mM with a good linearity (R²= 0.999). Almost no interference effect was observed for sensing of glucose in the presence of ascorbic acid, alanine, phenylalanine, fructose, sucrose, and NaCl.     

Flow Injection Amperometric Analysis of H2O2 at Platinum Nanoparticles Modified Pencil Graphite Electrode

A Pt nanoparticle modified Pencil Graphite Electrode (PGE) was proposed for the electrocatalytic oxidation and non‐enzymatic determination of H₂O₂ in Flow Injection Analysis (FIA) system. Platinum nanoparticles (PtNPs) electrochemically deposited on pretreated PGE (p.PGE) surface by recording cyclic voltammograms of 1.0 mM of H₂PtCl₆ solution in 0.10 M KCl at scan rate of 50 mV s⁻¹ for 30 cycles. Cyclic voltammograms show that the oxidation peak potential of H₂O₂ shifts from about +700 mV at bare PGE to +50 mV at PtNPs/p.PGE vs. Ag/AgCl /KCl (sat.). It can be concluded that PtNPs/p.PGE exhibits a good electrocatalytic activity towards oxidation of H₂O₂. Then, FI amperometric analysis of H₂O₂ was performed under optimized conditions using a new homemade electrochemical flow cell which was constructed for PGE. Linear range was found as 2.5 μM to 750.0 μM H₂O₂ with a detection limit of 0.73 μM (based on S_b/m of 3). As a result, this study shows the first study on the FI amperometric determination of H₂O₂ at PtNPs/p.PGE which exhibits a simple, low cost, commercially available, disposable sensor for H₂O₂ detection. The proposed electrode was successfully applied to determination of H₂O₂ in real sample.     

Titanium Dioxide/Multi-walled Carbon Nanotubes Composite Modified Pencil Graphite Sensor for Sensitive Voltammetric Determination of Propranolol in Real Samples

A very effective electrochemical sensor for the analysis of propranolol was constructed using TiO₂/MWCNT film deposited on the pencil graphite electrode as modifier. The modified electrode represented excellent electrochemical properties such as fast response, high sensitivity and low detection limit. The proposed sensor showed an excellent selective response to propranolol in the presence of foreign species and other drugs. The electrochemical features of the modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) technique which indicated a decrease in resistance of the modified electrode versus bare PGE and MWCNT/PGE. The surface morphology for the modified electrode was determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). Differential pulse technique (DPV) was used to determine propranolol which showed a good analytical response in the linear range of 8.5×10⁻⁸-6.5×10⁻⁶ M with a limit of detection 2.1×10⁻⁸ M. The TiO₂/MWCNT/PGE sensor was conveniently applied for the measurement of propranolol in biological and pharmaceutical media.     

多壁碳纳米管修饰玻碳电极用于过氧化氢的检测

构建用于过氧化氢检测的多壁碳纳米管修饰玻碳电极,循环伏安阳极最大电流法和计时安培电流法测试表明:碳纳米管能提高电极的有效表面积,并加速电子的传递.循环伏安阳极最大电流和计时安培响应电流均与过氧化氢的浓度变化成线性关系,两种检测方法的灵敏度和线性相关系数分别为2.8μA/(mmol.L-1)、0.997和1.5μA/(mmol.L-1)、0.971;检测方法过程简单,结果令人满意.     

硫酸双肼屈嗪修饰玻碳电极安培法测定过氧化氢

在1.0 mol/L H2SO4溶液中,在玻碳电极上修饰硫酸双肼屈嗪制得的修饰电极对过氧化氢还原有催化作用.研究了各种实验条件对修饰电极性能的影响.在-0.3 V工作电位下,用安培法测定过氧化氢的响应电流与其浓度在1.94×10-5～1.05×10-s mol·L-1范围内呈线性关系.该修饰电极具有制作简单,使用寿命长...     

A Hydrogen Peroxide Biosensor Combined HRP Doped Polypyrrole with Ferrocene Modified Sol-gel Derived Composite Carbon Electrode

Conducting polymers, because of bearing many attractive features, for example, shuttling electrons between the electrode surface and the entrapped reagents (enzymes, mediators, etc.) while preventing interference and electrode fouling, have been proposed as enzyme supports for electrochemical biosensors1-4. Polypyrrole, owing to its popularity to water solubility and the mild conditions used for electropolymerization, has been the most widely used monomer to entrap enzymes5-8. The sol-gel prog…     

铅笔芯电极表面多层自组装膜制备及其对牛血清白蛋白的测定

采用电沉积技术将金沉积在铅笔芯电极(PGE)上,借助Au-S作用,将L-半胱氨酸(L-Cys)组装于金表面,利用吖啶橙(AO)与L-半胱氨酸之间的静电作用,将吖啶橙间接组装于金表面,构建成三层自组装膜电极AO/L-Cys/Au/PGE。将该复合膜电极连接在电化学工作站的工作电极和辅助电极端之间,与参比电极浸入溶液中,构建了一个新的检测回路。采用电化学阻抗谱技术和循环伏安法对多层自组装膜的组装过程进行表征。利用吖啶橙与牛血清白蛋白(BSA)间的相互作用,采用零流电位法,通过对比加入不同浓度BSA后零流电位值的变化(ΔEzcp)对BSA进行检测。结果显示,在1.0×10-9～1.0×10-5mol/L范围内,ΔEzcp与BSA浓度的对数值呈良好线性,相关系数(r)为0.997 0,检出限为1.41×10-11mol/L。该方法选择性和重复性好,有望应用于其它蛋白的测定。