去甲肾上腺素在多壁碳纳米管修饰玻碳电极上的电化学行为

动物体内的去甲肾上腺素(NE)含量变化反映了肢体神经系统植物交感神经的活动状况,在临床和基础研究中非常重要[1-3]。用化学修饰电极研究儿茶酚胺类神经递质的电化学行为以及对其进行测定是目前分析化学比较活跃的研究领域[4-6]。利用羧基化后的多壁碳纳米管(MWC-NT)对电极表面     

Electrochemical oxidation of salicylic acid at well-aligned multiwalled carbon nanotube electrode and its detection

In this paper, an electrochemical sensor for sensitive and convenient determination of salicylic acid (SA) was constructed using well-aligned multiwalled carbon nanotubes as electrode material. Compared to the glassy carbon electrode, the electro-oxidation of SA significantly enhanced at the multiwalled carbon nanotube (MWCNT) electrode. The MWCNT electrode shows a sensitivity of 59.25 μA mM⁻¹, a low detection limit of 0.8 × 10⁻⁶ M and a good response linear range with SA concentration from 2.0 × 10⁻⁶ to 3.0 × 10⁻³ M. In addition, acetylsalicylic acid was determined indirectly after hydrolysis to SA and acetic acid, which simplified the detection process. The mechanism of electrochemical oxidation of SA at the MWCNT electrode is also discussed.     

Electrochemical determination of 8-hydroxydeoxyguanosine using a carbon nanotube modified electrode

In this work, a multi-wall carbon nanotube (MWNT) film-modified glassy carbon electrode (GCE) was constructed for the determination of 8-hydroxydesoxyguanosine (8-OHdG). The electrochemical behaviors of 8-OHdG were examined using cyclic voltammetry (CV) and linear sweep voltammetry (LSV), suggesting that MWNT film facilitates the electron transfer of 8-OHdG and then significantly enhances the oxidation peak current of 8-OHdG. Finally, a sensitive and simple electrochemical method with a good linear relationship in the range of 8.0 × 10⁻⁸ ∼ 5.0 × 10⁻⁶ mol 1⁻¹, was developed for the determination of 8-OHdG. The detection limit is 9.0 × 10⁻⁹ mol 1⁻¹ for 6-min accumulation. This newly-proposed method was successfully used to detect 8-OHdG in urine samples. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 3, pp. 351–356. The text was submitted by the authors in English.     

Electrochemical oxidation behavior of nitrite on a chitosan-carboxylated multiwall carbon nanotube modified electrode

A novel chitosan-carboxylated multiwall carbon nanotube modified glassy carbon electrode (MC/GCE) was developed to investigate the oxidation behavior of nitrite using cyclic voltammetry and differential pulse voltammetry modes. The electrochemical mechanism of the MC/GCE towards nitrite was discussed. The MC/GCE exhibited fast response towards nitrite with a detection limit of 1 × 10⁻⁷ mol l⁻¹ and a linear range of 5 × 10⁻⁷–1 × 10⁻⁴ mol l⁻¹. The possible interference from several common ions was tested. The proposed method was successfully applied in the detection of nitrite in real samples.     

碳纳米管修饰电极的电化学行为及对酪氨酸的测定

将经超声波处理的多壁碳纳米管液滴涂于碳糊电极上制成修饰电极(MWNTs/CPE).应用循环伏安法研究了酪氨酸(Tyr)在修饰电极上的电化学行为.测定结果表明,酪氨酸在3.5×10<'-6>～2.0×10<'-3>moL/L浓度范围内与峰电流成良好的线性关系.回归方程为Ip(μA)=0.058c(μmol/L)+5.21...     

Electrochemical determination of malachite green using a multi-wall carbon nanotube modified glassy carbon electrode

A multi-wall carbon nanotube (MWNT) film-modified electrode is described for the determination of malachite green (MG). The electrochemical profile of MG was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), suggesting that the MWNT film facilitates the electron transfer of MG in terms of a potential shift and then significantly enhances the oxidation peak current of MG. The experimental parameters, such as supporting electrolyte, thickness of MWNT film, scan rate and accumulation time, were optimized. Consequently, a sensitive and convenient electrochemical method is proposed for the determination of MG. The oxidation peak current is proportional to the concentration of MG over the range from 5.0 × 10⁻⁸ to 8.0 × 10⁻⁶ mol L⁻¹ obeying the following equation: i_p = 0.09 + 1.19 × 10⁷ C (r = 0.995, i_p in μA, C in mol L⁻¹). The detection limit is 6.0 × 10⁻⁹ mol L⁻¹ (signal to noise = 3) after 5 min of accumulation. Moreover, this method possesses good reproducibility (RSD is 5.6%, n = 8) as well as long-term stability. Finally, the new method was employed to determine MG in fish samples. Correspondence: W. Huang, Department of Chemistry, Hubei Institute for Nationalities, Enshi 445000, P.R. China     

Electrochemical detection of amino acids at carbon nanotube and nickel-carbon nanotube modified electrodes

The oxidation and enhanced detection of traditionally 'non-electroactive' amino acids at a single-wall carbon nanotube (SWNT) surface and at a nickel hydroxide film electrochemically deposited and generated upon the SWNT layer is reported. Different CNT are compared, with Nafion-dispersed SWNT offering the most favorable layer for constant-potential amperometric detection. Factors affecting the oxidation process, including the pH or applied potential, are assessed. The response of the SWNT-Nafion coated electrode compares favorably with that of copper and nickel disk electrodes under flow injection analysis (FIA) conditions. The electrodeposition of nickel onto the SWNT-Nafion layer (Ni-CNT) led to a dramatic enhancement of the analytical response (vs. that observed at the SWNT or nickel electrodes alone). The oxidative process at the Ni(OH)(2) layer has been studied and the increase in sensitivity rationalized. In the presence of amino acid the Ni-CNT layer undergoes an electrocatalytic process in which the amino acid reduces the newly formed NiO(OH) species. Furthermore, the attractive response of both the CNT and Ni-CNT layers has allowed these electrodes to be used for constant-potential FIA of various amino acids and indicates great promise for monitoring chromatographic effluents. Once again an improved signal was observed at the Ni-CNT electrode compared to nickel deposited upon a bare glassy carbon electrode (Ni-GC).     

A chitosan-multiwall carbon nanotube modified electrode for simultaneous detection of dopamine and ascorbic acid.

A chemically modified electrode based on a chitosan-multiwall carbon nanotube (MWNT) coated glassy carbon electrode (GCE) is described, which exhibits an attractive ability to determine dopamine (DA) and ascorbic acid (AA) simultaneously. The modified electrode exhibited a high differential pulse voltammetry (DPV) current response to DA at 0.144 V and AA at -0.029 V (vs. SCE) in a 0.1 mol l(-1) phosphate buffer solution (pH = 7.2). The properties and behaviors of the chitosan-multiwall carbon nanotube modified electrode (MC/GCE) were characterized using cyclic voltammetry (CV) and DPV methods. The mechanism for the discrimination of dopamine from ascorbic acid at MC/GCE is discussed. The linear calibration range for DA and AA were 5 x 10(-7) mol l(-1) to 1 x 10(-4) mol l(-1) (r = 0.997), and 5 x 10(-6) mol l(-1) to 1 x 10(-3) mol l(-1) (r = 0.996), respectively. The MC/GCE showed good sensitivity, selectivity and stability.     

对苯二酚在碳纳米管修饰玻碳电极的电化学行为及电化学动力学研究

碳纳米管(Carbon Nanotubes,CNT)自1991年发现以来,因其结构所具有的高比表面,高电导率,稳定的化学性质与超常的机械强度已成为世界范围内的研究热点,并应用于催化、气体储藏和电极材料等领域。用CNT修饰的电极具有良好的电化学性能并且已经取得了很好的实验结果[1],因此研究碳     

阿奇霉素在多壁碳纳米管修饰电极上的电化学行为及其测定

运用循环伏安法与线性扫描伏安法研究了阿奇霉素在多壁碳纳米管修饰玻碳电极上的电化学行为,建立了一种直接测定阿奇霉素的电化学分析方法。结果表明,与裸玻碳电极相比,多壁碳纳米管修饰电极能显著提高阿奇霉素的氧化峰电流,阿奇霉素的电极过程完全不可逆,存在典型的吸附特性。在优化的实验条件下,氧化峰电流与阿奇霉素浓度在3.0×10-7～2.5×10-5 mol/L和2.5×10-5～5.0×10-4 mol/L范围内呈现良好的线性关系,检出限为1.0×10-7 mol/L。     

Electrochemical determination of ferulic acid in Chinese traditional medicine Xiao Yao Pills at electrode modified with carbon nanotube

The electrochemical behaviors of ferulic acid were investigated at the glassy carbon electrode modified with multi-walled carbon nanotube. In pH 5.5, 0.1 mol l⁻¹ HAc-NaAc buffer solution, ferulic acid exhibited a pair of stable and sensitive redox signals at the modified electrode. The reaction mechanism was explored. Through the cyclic voltammetry, trace amount of ferulic acid was detected quantitatively. In the range of 1 × 10⁻⁵ to 5 × 10⁻³ mol l⁻¹, the oxidation peak currents of ferulic acid have a linear relationship to the concentrations, the limit of detection was estimated to be 1 × 10⁻⁷ mol l⁻¹ (S/N = 3). The influences of substrate, pH and interference of coexisting substances were investigated for response properties of the electrode. Actual Xiao Yao Pill samples were analyzed and satisfactory results were obtained, which meant that the method could be used to detect the trace amount of ferulic acid in medicament. The article is published in the original. Published in Elektrokhimiya in Russian, 2009, Vol. 45, No. 2, pp. 180–184.     

肾上腺素在对甲苯磺酸修饰电极上的电化学行为

研究了对甲苯磺酸在玻碳电极上电化学聚合的条件及修饰电极的电化学特性, 发现该聚合膜对肾上腺素的电氧化有显著的催化作用, 在pH 7.0的磷酸盐缓冲溶液中, 搅拌富集40 s后, 用循环伏安法对肾上腺素进行了测定, 线性范围: 4.05×10-7～9.45×10-6 mol/L, 检出限为3.2×10-8 mol/L. 对2.0×10-6 mol/L肾上腺素平行测定7次相对标准偏差为2.4%. 该电极有效地排除了抗坏血酸的干扰, 具有良好的稳定性和重现性.     

Multipurpose organically modified carbon nanotubes: from functionalization to nanotube composites

We show that covalent functionalization of carbon nanotubes (CNTs) via 1,3-dipolar cycloaddition is a powerful method for enhancing the ability to process CNTs and facilitating the preparation of hybrid composites, which is achieved solely by mixing. CNTs were functionalized with phenol groups, providing stable dispersions in a range of polar solvents, including water. Additionally, the functionalized CNTs could easily be combined with polymers and layered aluminosilicate clay minerals to give homogeneous, coherent, transparent CNT thin films and gels.     

水合肼在多壁碳纳米管修饰电极上的电化学行为及测定

报道了水合肼在碳纳米管修饰电极上的电化学行为以及水合肼测定的新方法。与裸玻碳电极相比,多壁碳纳米管修饰玻碳电极使水合肼的氧化峰电流显著提高,同时氧化过电位降低,测定灵敏度大为提高。优化了底液、pH、修饰剂量等测定条件。在最佳条件下,该修饰电极测定水合肼的线性范围为2.9×10-8~9.8×10-4mol/L,线性相关系数为-0.9945,检出限为1.0×10-9mol/L。对1.0×10-4mol/L的水合肼平行测定10次的相对标准偏差为4.4%。此方法已用于模拟水样中水合肼的测定。     

肾上腺素在对氨基苯磺酸修饰玻碳电极上的电化学行为

采用电化学聚合法首次制备了对氨基苯磺酸修饰玻碳电极。实验表明,该修饰电极对肾上腺素(EP)有明显的电催化特性。在pH 7.6的磷酸盐缓冲溶液(PBS)中,抗坏血酸(AA)和EP在修饰电极上的电位分别为-0.124 V和0.192V。电位差达到300 mV,且在高浓度的AA的存在下可以实现对EP的测定。EP在该电极上检测的线性范围是5.0×10-7~1.0×10-4mol/L,检出限为3.6×10-8。此法已用于针剂样品的测定。     

抗坏血酸在离子液体修饰玻碳电极上的电化学行为

利用离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)对玻碳电极(GCE)进行修饰,制备了BMI-MBF4/GCE电极.在0.1mol/L的磷酸盐缓冲溶液中,采用循环伏安法研究了抗坏血酸在BMIMBF4/GCE电极和裸玻碳电极(GCE)上的电化学行为.结果表明,pH=5.7的磷酸盐缓冲溶液为最佳测定底液,最佳富集时间为120s;BMIMBF4/GCE对抗坏血酸的氧化反应有很好的电化学催化作用.抗坏血酸的氧化峰电流与其浓度在2.0×10-4～1.0×10-2 mol/L的范围内呈良好的线性关系,相对标准偏差为4.53%(n=5).     

Electrochemical sensor using glassy carbon electrode modified with acylpyrazolone-multiwalled carbon nanotube composite film for determination of xanthine

In this work, an electrochemical sensor 1-phenyl-3-methyl-4-(2-furoyl)-5-pyrazolone/multiwalled carbon nanotubes/glassy carbon electrode (GCE) was prepared for the determination of xanthine (XN) in the presence of an excess of uric acid. Cyclic voltammetry and differential pulse voltammetry were used to characterize the electrode. The oxidation of XN occurred in a well-defined peak having E _p 0.73 V in phosphate buffer solution of pH 6.0. Compared with the bare GCE, the electrochemical sensor greatly enhanced the oxidation signal of XN with negative shift in peak potential about 110 mV. Based on this, a sensitive, rapid, and convenient electrochemical method for the determination of XN has been proposed. Under the optimized conditions, the oxidation peak current of XN was found to be proportional to its concentration in the range of 0.3~50 μM with a detection limit of 0.08 μM. The analytical utility of the proposed method was demonstrated by the direct assay of XN in urine samples and was found to be promising at our preliminary experiments.     

双氯芬酸钠在多壁碳纳米管修饰电极上的电化学行为及其应用

应用循环伏安法和线性扫描伏安法研究了双氯芬酸钠在多壁碳纳米管修饰电极上的电化学行为,建立了一种直接测定双氯芬酸钠的电分析方法.在0.1 mol/L HClO4溶液中,双氯芬酸钠的氧化峰电位在0.38 V(vs Ag/AgCl),峰电流与浓度在2.0×10-7 mol/L～7.0 × 10-6 mol/L范围内呈线性关系,开路富集3 min后检出限为9.0×10-8 mol/L.5×10-6 mol/L双氯芬酸钠溶液平行测定10次的相对标准偏差(RSD)为4.5%.已用于扶他林片剂中双氯芬酸钠的测定.     

Reversible electrochemistry of DNA on multi-walled carbon nanotube modified electrode

Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues, respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.