聚苯基荧光酮修饰玻碳电极吸附溶出伏安法测定痕量汞

研究利用聚苯基荧光酮修饰玻碳电极测定痕量汞的溶出伏安法,在0.1 mol.L-1氨水-NH4Cl缓冲溶液中(pH 9.5),开路搅拌,Hg(Ⅱ)富集于修饰电极表面,通过介质交换至0.1mol.L-1盐酸溶液中,于-0.40 V还原后阳极化线性扫描,在0 V左右处获得一灵敏汞的溶出峰。其氧化峰电流与Hg(Ⅱ)浓度在9.0×10-8~8.0×10-7mol.L-1范围内呈线性关系,开路富集5 min,检出限达2.0×10-8mol.L-1。应用此方法于尿液中汞的测定,所得平均RSD值小于4.02%,回收率试验结果在98.4%~103.2%间。     

多壁碳纳米管修饰玻碳电极伏安法测定氯霉素

研究了氯霉素(CAP)在多壁碳纳米管修饰玻碳电极上的电化学行为.发现在pH=2.0的0.1 mol/LKCl-HCl底液中,CAP在该修饰电极上有一灵敏的还原峰(Ep=-0.36 V vs.Ag/AgCl),峰电流与CAP浓度成正比,线性范围为6.0×10-6~2.7×10-4mol/L,检测限达3.0×10-6mol/L.该方法灵敏、准确,用于模拟样品和实际样品的测定,结果满意.     

维生素b12在多壁碳纳米管修饰玻碳电极上的电化学行为及其分析测定

维生素b12;多壁碳纳米管;循环伏安法;修饰电极     

Electrochemistry and Adsorptive Stripping Voltammetric Determination of Amoxicillin on a Multiwalled Carbon Nanotubes Modified Glassy Carbon Electrode

The study of electrochemical behavior of amoxicillin (AMX), a β‐lactam antibiotic, is described on a multiwalled carbon nanotubes (MWCNTs) modified electrode by electrochemical impedance spectroscopy (EIS) and adsorptive stripping voltammetry for sensitive determination of AMX in pharmaceutical and human urine samples within a wide pH range from 2.0 to 10.0. Also, studies by Fe₂O₃ nanoparticles modified carbon paste electrode show that iron oxide impurities in the MWCNTs are not active sites for sensing of amoxicillin. Under optimized conditions, the oxidation peak has two linear dynamic ranges of 0.6–8.0 and 10.0–80.0 μM with a detection limit of 0.2 μM and a precision of <4%.     

Electrochemical Determination of Tannins Using Multiwall Carbon Nanotubes Modified Glassy Carbon Electrode

A novel chemically modified electrode is prepared on the basis of the attachment of multiwall carbon nanotubes (MWNTs) to the surface of a glassy carbon electrode (GCE) in the presence of a hydrophobic surfactant. The electrochemical behavior of tannins at the MWNTs-modified GCE is investigated. Tannins yield a well-defined oxidation at about 0.30 V (SCE) at the MWNTs-modified GCE. MWNT-film shows remarkable enhancement effect on the oxidation peak current of tannins. The experimental parameters are optimized, and a direct electrochemical method to detect tannins is proposed. The oxidation peak current is proportional to the concentration of tannins over the range from 4 × 10^–7 to 2 × 10^–4 M, and the detection limit is 1 × 10^–7 mol/l after 5 min of accumulation. The relative standard deviation of 6% for determination of 2 × 10^–6 mol/l tannins indicates excellent reproducibility. The analysis method is demonstrated by using tea and Chinese gall samples.     

碳纳米管修饰电极差示脉冲阳极溶出伏安法测定腺嘌呤

在HAc NaAc缓冲溶液中,玻碳电极上修饰的少量碳纳米管对腺嘌呤的氧化起增强作用.研究了腺嘌呤在修饰电极上的伏安行为,优化了电氧化的最佳条件,并对其进行含量测定.方法的线性范围为2.0×10-8～1.0×10-5mol/L,检出限为1.0×10-9mol/L.用于模拟样品中痕量腺嘌呤的测定,结果满意.     

Electrochemical Determination of 4-Nitrophenol Using a Single-Wall Carbon Nanotube Film-Coated Glassy Carbon Electrode

A single-wall carbon nanotubes (SWNT) film coated glassy carbon electrode (GCE) was fabricated for the direct determination of 4-nitrophenol (4-NP). The electrochemical behaviors of 4-NP at the SWNT-film coated GCE were examined. In 0.1M phosphate buffer with a pH of 5.0, 4-NP yields a very sensitive and well-defined reduction peak at the SWNT-modified GCE. It is found that the SWNT film exhibits obvious electrocatalytic activity towards the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. The reduction peak current varies linearly with the concentration of 4-NP ranging from 1×10^–8 to 5×10^–6M, and the detection limit is 2.5×10^–9M after 3min of open-circuit accumulation. The relative standard deviation at 2×10^–7M 4-NP was about 6% (n=10), suggesting excellent reproducibility. This new method was successfully employed to determine 4-NP in several lake water samples.     

多壁碳纳米管修饰玻碳电极测定乙炔雌二醇

多壁碳纳米管修饰玻碳电极测定乙炔雌二醇;多壁碳纳米管;乙炔雌二醇;化学修饰电极;电化学测定     

Modified Glassy Carbon Electrode with Multiwall Carbon Nanotubes as a Voltammetric Sensor for Determination of Leucine in Biological and Pharmaceutical Samples

Abstract

A simple and highly sensitive method is described for voltammetric determination of leucine in blood and urine samples; namely, a glassy carbon electrode with an effective method is modified with multiwall carbon nanotubes (MWNTs). The cyclic voltammetric results indicated that MWNTs remarkably enhanced electrocatalytic activity toward the oxidation of leucine. Under the optimum condition the calibration curve was linear in the concentration range 9.0 × 10^?6 ? 1.5 × 10^?3 mol L^?1, with the detection limit of 3.0 × 10^?6 mol L^?1 and a relative standard deviation (RSD%) lower than 3.0% (n = 5). Also, some kinetic parameters were determined and a multistep mechanism for oxidation of leucine was proposed.     

碳纳米管碳糊电极吸附伏安法测定西沙必利

用循环伏安法和差分脉冲伏安法研究了西沙必利在多壁碳纳米管碳糊电极上的伏安行为和反应机理。在pH6.09Britton-Robinson缓冲液中,西沙必利在 0.89V(vs.SCE)处产生一灵敏的氧化峰。该氧化峰是由吸附控制的两电子一质子不可逆过程。其峰电流与浓度在4.0×10?8~2.0×10?5mol/L范围内呈线性关系(r=0.997),检出限为1.0×10?8mol/L。对5×10?6mol/L西沙必利平行测定10次的相对标准偏差为3.68%。用本法测定了片剂中西沙必利的含量,加标回收率为94.0%~104%。     

杯芳烃修饰玻碳电极吸附溶出伏安法测定微量铅

研究了以杯芳烃衍生物修饰玻碳电极,以其吸附溶出伏安法测定微量铅。对富集时间、铅的浓度、支持电解质、样品溶液pH值及部分离子干扰等进行了实验。实验发现以氢氧化钠溶液处理修饰电极可提高测定灵敏度,经过优化处理后,线性范围和检出限分别为5.0×10-7～1.0×10-5mol/L和1.0×10-8mol/L。应用本法对合成水样进行了测定,结果满意。本文还对吸附溶出机理进行了讨论。     

Adsorptive Stripping Voltammetric Determination of 2,4-Dichlorophenol by Laponite Modified Carbon Paste Electrode

A laponite modified carbon paste electrode was prepared, characterized and applied for the 2,4-dichlorophenol (2,4-DCP) voltammetric determination. It takes advantage of the ability of laponite to adsorb phenols, as well as of its availability and very low cost. Kinetic and equilibrium data for 2,4-DCP adsorption by laponite in aqueous dispersions demonstrated that the adsorption process obeyed a pseudo first order kinetic model and was consistent with the formation of adsorbed multilayers on a surface with heterogeneous pore distribution. The composite paste electrode exhibited a heterogeneous surface with 65 % increased surface area and 27 % enhanced catalytic activity compared to the unmodified one. The adsorptive stripping voltammetric determination of 2,4-DCP at an electrode with an optimized graphite:laponite ratio of 55 : 15 w% using a 3 min accumulation time at pH 5.5 was found to be suitable for its quantification in the linear concentration range extended up to 50 μmol L⁻¹ with a sensitivity of 0.56 μA L μmol⁻¹ and a LOD of 0.2 μmol L⁻¹ (S/N=3).The 2,4-DCP electrochemical response was not affected by the presence of some structurally similar phenols, like catechol and p-nitrophenol, while resorcinol, 2-chlorophenol, and 4-chlorophenol presented interferences. The results were validated by 2,4-DCP determination in spiked tap water.     

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.     

Electrochemical Study and Selective Determination of Dopamine at a Multi-Wall Carbon Nanotube-Nafion Film Coated Glassy Carbon Electrode

A homogeneous and stable suspension of multi-wall carbon nanotubes (MWNT) was achieved by dispersing MWNT into 0.1% Nafion ethanol solution. A uniform MWNT-Nafion cast film was obtained over a glassy carbon electrode (GCE) via solvent evaporation. The electrochemical behavior of dopamine (DA) was examined, and a reversible two-electron redox reaction was observed. In comparison with the bare GCE and the Nafion-modified GCE, the MWNT-Nafion modified GCE shows obvious electrocatalytic activity towards DA. Moreover, the MWNT-Nafion film coated electrode exhibits excellent selectivity towards DA even in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The oxidation peak current was proportional to the concentration of DA over the range of 1×10^–8 to 1×10^–5molL^–1, and a detection limit of 2.5×10^–9molL^–1 was obtained after 2min. of open-circuit accumulation. The dispersion and morphology of MWNT-Nafion film were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transfer (FT) IR spectra.     

多壁碳纳米管修饰玻碳电极伏安法测定香草醛

制备了羧基化多壁碳纳米管修饰玻碳电极(c-MWCNTs/GCE),采用循环伏安法在0.5 mol/L HCl中研究了食品添加剂香草醛的电化学行为。结果显示,该修饰电极对香草醛的电化学氧化具有良好的电催化作用,与裸玻碳电极相比电流响应显著增强。香草醛在该修饰电极上的氧化为不可逆的扩散控制过程。在最佳条件下,采用二阶导数线性扫描伏安法进行测定,香草醛的氧化峰电流与其浓度在0.1～6.0μmol/L和6.0～100μmol/L范围内呈良好的线性关系,检出限(S/N=3)为0.02μmol/L。该修饰电极具有良好的重现性(RSD=4.6%)和稳定性。方法应用于食品中香草醛的测定,回收率为96.3%～104%。     

聚赖氨酸/多壁碳纳米管修饰电极测定大米中的铅

通过滴涂及电聚合方式分别将多壁碳纳米管和赖氨酸共修饰于玻碳电极上,制备出聚赖氨酸/多壁碳纳米管修饰电极,并建立了阳极溶出伏安法测定铅离子的新方法。采用线性扫描伏安法及循环伏安法研究了铅离子在修饰电极上的电化学行为,并考察了测定底液、底液p H值、富集电位、富集时间等条件的影响。在最佳实验条件下,铅离子的溶出峰电流与其浓度在2.0×10-7~8.0×10-5mol·L-1范围内呈良好的线性关系,检出限为1.0×10-7mol·L-1。利用所制备的修饰电极对大米样品进行加标回收实验,回收率为98%~102%。该方法具有良好的灵敏度和稳定性,已成功应用于大米样品中铅离子的测定。     

Application of a Carbon Nanotube Modified Electrode in Anodic Stripping Voltammetry for Determination of Trace Amounts of 6-Benzylaminopurine

Carbon nanotubes were modified on the surface of a glassy carbon electrode (GC) and initially applied in semi-derivative anode stripping voltammetry for the determination of 6-benzylaminopurine. The experiments demonstrated that the presence of the carbon nanotube greatly increased the current of the oxidation peak of benzylaminopurine. Cyclic voltammetry (CV) and semi-derivative voltammetry were used in a comparative investigation into the electrochemical oxidation of benzylaminopurine with the modified electrode. Studies on the effect of pH on the peak current and potential were carried out over the pH range of 9.013.0 with the NH₃–NH₄Cl buffer solution. A pH of 10.0 was chosen as the optimum pH. Other experimental parameters, such as film thickness, accumulation potential, temperature etc. were optimized. The anodic peak current was found to be linearly related to the concentration of benzylaminopurine over the range of 4.0×10^–8 to 1.0×10^–5mol·L^–1 with a detection limit of 5.0×10^–9mol·L^–1 in an accumulation time of 5min. Interferences of some inorganic and organic species on the response have been studied.     

Direct Electrochemistry of Catalase on Single Wall Carbon Nanotubes Modified Glassy Carbon Electrode

Direct electrochemistry of catalase (Ct) has been studied on single wall carbon nanotubes (SWNTs) modified glassy carbon (GC) electrode. A pair of well-defined nearly reversible redox peaks is given at -0.48 V (vs. SCE) in 0.1 mol/L phosphate solution (pH 7.0).The peak current in cyclic voltammogram is proportional to the scan rate. The peak potential of catalase is shifted to more negative value when the pH increases. Catalase can adsorb on the SWNTs modified electrode.     

Differential Pulse Anodic Stripping Voltammetric Determination of Lead with Heparin Modified Electrode

Introduction Overall exposure to lead is of public health concern because of several hazardous effects that may occur to human beings. Lead poisoning may provoke irritability, anorexia, malaise and headache. Intoxication progress may lead to attacks of abdominal pain until coma and death.1 The determination of trace lead in variety of en-vironmental samples is of great importance since lead is recognized as a cumulative poison to animals and hu-mans. There is a constant demand for improved an…     

漆酚铝高分子修饰碳糊电极用于溶出伏安法测定痕量银

漆酚铝树脂;漆酚铝高分子修饰碳糊电极用于溶出伏安法测定痕量银