碳纳米管修饰电极同时测定邻苯二酚和对苯二酚

用十二烷基磺酸钠(SDS)分散碳纳米管(CNTs),通过层层组装(LBL)聚二甲基二烯丙基氯化铵(PDDA)和CNTs构筑PDDA/CNTs多层膜电极.利用紫外-可见光谱法对PDDA/CNTs多层膜的组装过程进行监测,用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了邻苯二酚和对苯二酚同时存在时PDDA/CNTs多层膜电极上的电化学行为.结果表明,碳纳米管修饰电极对邻苯二酚和对苯二酚有较好的电催化活性和电分离作用,邻苯二酚和对苯二酚无需经过分离即可同时被检出.在修饰电极上的线性范围如下:邻苯二酚为2.0×10-6~1.4×10-4mol/L,线性相关系数R=0.9991;对苯二酚为2.0×10-6~1.4×10-4mol/L,线性相关系数R=0.9987.     

聚L-半胱氨酸/多壁碳纳米管复合修饰电极同时测定邻苯二酚和对苯二酚

将羧基化多壁碳纳米管分散在L-半胱氨酸溶液中并滴涂在玻碳电极表面.将上述电极在pH 6.9的B-R缓冲溶液中,于-1.0～2.5 V的电位范围内进行电聚合,制备了聚L-半胱氨酸/多壁碳纳米管复合修饰电极(Pol-L-Cys/MWCNTs/GCE).研究发现,邻苯二酚和对苯二酚在聚L-半胱氨酸/多壁碳纳米管复合修饰电极上分别出现了一对氧化还原峰,且两者的氧化峰电位差达101 mV,提出了用微分脉冲伏安法同时测定邻苯二酚和对苯二酚的方法.氧化峰电流与邻苯二酚和对苯二酚的浓度在1.0×10-5～1.0×10-3mol·L-1呈线性关系,检出限(3S/N)均达1.0×10-5mol·L-1.修饰电极用于模拟样品中邻苯二酚和对苯二酚的测定,回收率在82.0%～107.0%之间.     

Simultaneous Determination of Hydroquinone and Catechol at an Activated Glassy Carbon Electrode

A selective and very simple electrochemical method, based on anodization of a glassy carbon electrode (GCE), was developed for the simultaneous detection of hydroquinone (HQ) and catechol (CT). It was found that the activated GCE showed an excellent catalytic behavior and enhanced reversibility towards the oxidation of both HQ and CT. The redox responses from the mixture of HQ and CT were easily resolved at an activated GCE. The detection limits for HQ and CT were calculated to be 0.16 and 0.11 μM, respectively. The activated GCE was successfully examined for real sample analysis with tap water and it showed a stable and reliable recovery data.     

聚苯胺-石墨烯修饰玻碳电极同时测定邻苯二酚和对苯二酚

本文制备了聚苯胺-石墨烯修饰玻碳电极,并用循环伏安(CV)法和微分脉冲伏安(DPV)法研究了邻苯二酚(CC)和对苯二酚(HQ)在该修饰电极上的电化学行为。实验结果表明,相对于裸玻碳电极,HQ和CC在聚苯胺-石墨烯修饰电极上的氧化峰电流显著提高,氧化峰电位相差104.8mV,实现了CC和HQ的选择性测定。DPV法同时测定二酚时,HQ和CC分别在1.0×10-6~8.0×10-4 mol/L浓度范围内与其峰电流呈良好的线性关系,相关系数R分别为0.998、0.997,检出限(S/N=3)分别为1.0×10-7、8.0×10-8mol/L。将该方法用于模拟水样分析,回收率为95.3%~103.5%。     

聚谷氨酸修饰电极同时检测对苯二酚和邻苯二酚

以谷氨酸单体为初始试剂,利用电化学聚合方法制备得到聚谷氨酸修饰电极.考察了电化学聚合条件(电位、扫速及扫描圈数)对修饰电极的影响,运用电化学方法对所制备的修饰电极进行了表征.此修饰电极对对苯二酚和邻苯二酚的电化学氧化还原显示出很高的催化能力,显著降低了二者的氧化电位,改善了二者的电化学可逆性,同时增强了二者的氧化还原峰...     

金纳米粒子-过氧化聚吡咯-碳纳米管复合膜修饰电极同时测定对苯二酚和邻苯二酚

将多壁碳纳米管(MWCNTs)滴涂于复合陶瓷碳电极(CCE)表面,采用电化学方法在碳纳米管表面逐层沉积过氧化聚吡咯(OPPy)和金纳米粒子(AuNPs),制得金纳米粒子-过氧化聚吡咯-多壁碳纳米管复合膜修饰电极(AuNPs-OPPy-MWCNTs/CCE).采用扫描电镜和电化学方法对修饰电极进行了表征.在0.10 mol/LPBS (pH 7.0)缓冲溶液中研究了对苯二酚(HQ)和邻苯二酚(CC)在修饰电极上的电化学行为.结果表明,修饰电极对HQ和CC的电极过程具有良好的电化学响应和区分效应.基于此建立了一阶导数伏安法同时测定HQ和CC的方法,HQ和CC的线性范围均为2.0×10-7～ 1.0×10-4 mol/L,检出限分别为6.0×10-8 mol/L和8.0×10-8 mol/L(S/N=3).模拟水样中的加标回收率分别为96.2％～99.8％ (HQ)和96.0％～100.0％,表明本方法具有良好的实用性.     

Amperometric Detection of Morphine at Preheated Glassy Carbon Electrode Modified with Multiwall Carbon Nanotubes

A highly sensitive and fast responding sensor for the determination of morphine is described. The multiwall carbon nanotubes immobilize on preheated glassy carbon electrode (5 min at 50 °C) by gently rubbing of electrode surface on a filter paper supporting the carbon nanotubes.The results indicated that carbon nanotubes(CNTs) modified glassy carbon electrode exhibited efficiently electrocatalytic oxidation for morphine with relatively high sensitivity, stability and long life. Under conditions of cyclic voltammetry, the potential for oxidation of morphine is lowered by approximately 100 mV and the current is enhanced significantly (10 times) in comparison to the bare glassy carbon electrode at wide pH range (2–9). The electrocatalytic behavior is further exploited as a sensitive detection scheme for morphine determination by hydrodynamic amperometry. Under the optimized conditions the calibration plots are linear in the concentration range 0.5–150 μM with the calculated detection limit (S/N=3) of 0.2 μM and sensitivity of 10 nA/μM and a relative standard deviation (RSD) of 2.5% (n=10). The amperometric response is extremely stable, with no loss in sensitivity over a continual 30 min operation. Such attractive ability of multiwall carbon nanotubes (MWCNTs) modified GC electrode, suggests great promise for a morphine amperometric sensor. Finally the ability of the modified electrode was evaluated for simultaneous determination of morphine and codeine.     

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.     

Simultaneous Determination of Catechol and Hydroquinone on Nano-Co/L-Cysteine Modified Glassy Carbon Electrode

In this study, a novel and highly sensitive electrochemical method for simultaneous determination of catechol (CC) and hydroquinone (HQ) was developed, which worked at GCE modified with Nano cobalt (Nano-Co) by electrodeposition and L-Cysteine by electrochemical polymerization. The Nano-Co/L-Cysteine GCE was investigated by cyclic voltammetry (CV), SEM and EIS. The excellent conditions have been selected including supporting electrolyte, pH, accumulation time and scan rate. The calibration curves of were obtained that the linear regression equation was I=0.0734c+6×10⁻⁶ in the range of 5.8 μM to 103 μM (R²=0.9942) for CC and the linear regression equation was I=0.0566c+5×10⁻⁶ in the range of 5.8 μM to 100 μM (R²=0.9967) for HQ. The obtained detection limits of CC and HQ both were 6×10⁻⁷ M. The modified electrode was successfully applied to the simultaneous determination of CC and HQ in water samples.     

纳米氧化铜-碳纳米管修饰玻碳电极同时检测邻、对苯二酚

以商品化纳米氧化铜和羧化碳纳米管作为玻碳电极修饰材料,结合了两种材料的放大电信号和电催化性能,所构建的复合物修饰电极可区分性质相近的同分异构体邻苯二酚和对苯二酚的信号,同时可进一步放大两种酚的峰电流。 因此该基于纳米氧化铜和碳纳米管的电化学传感器可用于邻苯二酚和对苯二酚的同时检测。 采用循环伏安法对复合物中两种材料的比例、修饰量以及支持电解质pH进行了优化:纳米氧化铜和碳纳米管质量比为5∶1,修饰量为9 μL,pH=7.4的磷酸盐缓冲溶液被用作电解质溶液。 在优化的条件下,邻苯二酚和对苯二酚的微分脉冲伏安扫描峰电流与浓度在6.0×10^-7~3.0×10^-3 mol/L范围内均呈良好的线性关系,检出限(S/N=3)分别为1.0×10^-7和1.6×10^-7 mol/L。 该方法具有成本低、操作简便、快速的特点,对实际水样的加标回收率在94.6%~101.1%范围内,具有较好的实际应用前景。     

Cysteamine Capped Silver Nanoparticles and Single‐walled Carbon Nanotubes Composite Coated on Glassy Carbon Electrode for Simultaneous Analysis of Hydroquinone and Catechol

A stable complex of silver nanoparticles (Ag NPs) capped by cysteamine (Cst) together with single‐walled carbon nanotube (CNTs) was used to modify a glassy carbon electrode (GCE) for simultaneous detection of hydroquinone (HQ) and catechol (CT). The resulting electrode (AgCst‐CNTs/GCE) showed excellent electrocatalysis and reversibility towards this electroactive pair. The peak separations of their oxidation‐reduction peaks decreased significantly, compared with those of the unmodified GCE. The signal responses of the AgCst‐CNTs/GCE were 5‐fold higher while its peak potential separation remained unchanged (ca. 130 mV), compared to the CNTs‐modified GCE. The oxidation peak currents obtained for HQ and CT exhibited linearly from submicromolar to hundred micromolar concentrations without any cross‐interference. The modified electrode possessed a very large active surface area with a detection limit (S/N=3) of 10 and 40 nM for HQ and CT, respectively. The sensor was demonstrated for the analysis of river water and topical cream as evinced by high accuracy and reproducibility.     

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.     

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.     

纳米金修饰玻碳电极测定邻苯二酚

采用恒电位沉积方法将HAuCl4直接还原成纳米金并修饰于玻碳电极表面,制备了对邻苯二酚具有电催化氧化作用的纳米金修饰电极。邻苯二酚在该修饰电极上发生一可逆的氧化还原反应。在磷酸盐缓冲溶液(pH 7.5)中,当邻苯二酚的浓度为3.0×10-3mol.L-1时,与裸玻碳电极相比,其Epa负位移了170 mV,Epc正位移了50 mV,ΔE下降为60 mV,且峰电流显著增大,氧化峰电流与邻苯二酚浓度在5.0×10-6~4.2×10-3mol.L-1范围内呈线性关系,相关系数为0.997 6,检出限(3σ)为5.0×10-7mol.L-1。在浓度为5.0×10-4mol.L-1测得RSD(n=10)为2.9%,回收率在98.0%~101.0%之间。     

肾上腺素在多壁碳纳米管修饰金电极上的电化学行为及测定

报道了一种测定肾上腺素的化学修饰电极和电化学分析方法。与裸金电极相比,刚果红改性的多壁碳纳米管修饰金电极可显著提高肾上腺素的氧化峰电流。实验优化了底液、pH值、修饰剂量、富集电位和富集时间等条件,建立了一种直接测定肾上腺素的高灵敏的电化学分析方法。该方法测定肾上腺素的线性范围为4.0×10-7~2.0×10-4mol.L-1;富集30 s后的检出限为8.5×10-8mol.L-1;对2.0×10-5mol.L-1的肾上腺素平行测定10次的相对标准偏差为4.9%。此方法已成功用于盐酸肾上腺素注射液中含量的测定。     

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     

银掺杂聚L-甲硫氨酸修饰电极同时测定对苯二酚和邻苯二酚

用循环伏安法制备了银掺杂聚L-甲硫氨酸修饰玻碳电极,研究了对苯二酚和邻苯二酚在该修饰电极上的电化学行为,建立了同时测定对苯二酚和邻苯二酚的新方法.研究发现,在pH=5.0的磷酸盐缓冲溶液中,扫速为100 mV/s时,对苯二酚和邻苯二酚在银掺杂聚L-甲硫氨酸修饰玻碳电极上均出现1对氧化还原峰,峰电位分别为:Epa=0.228 V、Epc =0.162 V和Epa=0.347 V、Epc =0.287 V,二者的氧化峰电位差达119 mV,还原峰差达125 mV.在最佳的条件下,用差分脉冲伏安法同时测定邻苯二酚和对苯二酚的线性范围为3.00 ×10-6～1.00 ×10-4mol/L,检出限为8.0×10-7 mol/L(对苯二酚)和5.0×10-7 mol/L(邻苯二酚).此法用于废水样中对苯二酚和邻苯二酚的测定,获得满意结果.     

镍席夫碱膜修饰电极对对苯二酚的电催化作用及其测定

本文将合成的双水杨醛缩环己二胺镍配合物(Ni(Ⅱ)-salch)修饰至玻碳电极表面制得了镍席夫碱膜修饰电极.循环伏安实验结果表明,该修饰电极对对苯二酚有显著的电催化作用.以0.5次微分线性扫描法测定对苯二酚,当其浓度在1.5×10-6～6.5×10-4 mol/L范围时,还原峰电流与其浓度呈良好的线性关系,相关系数为0...     

金电极上苯二酚异构体的电化学性质及同时测定

采用循环伏安法研究了邻苯二酚(CAT)、间苯二酚（RE）和对苯二酚(HQ)在0.5 mol/L硫酸水溶液中的电化学行为,循环伏安法和差分脉冲伏安法研究了CAT、RE 和HQ共存体系的伏安行为。 实验结果表明,在pH=0的硫酸水溶液中,扫描速率为10 mV/s,循环伏安法扫描电位在0～1.2 V（vs.Ag/Cl）时,分离效果明显。 本文采用差分脉冲伏安法,测定了CAT、RE和HQ的混合物,检出限依次为3.9×10-6、3.9×10-6和7.8×10-6 mol/L。 将该方法用于合成样品测定,其精密度和准确度均满足分析要求。     

Simultaneous Electrochemical Determination of Hydroquinone and Catechol at MWNTs and Cobalt(II) Tetrakisphenylporphyrin Modified Electrode

A multi-wall carbon nanotubes (MWNTs) and cobalt(II) tetrakisphenylporphyrin (Co(II)TPP) modified glassy carbon electrode (MWNTs/Co(II)TPP/GCE) has been prepared. It can be used for individual or simultaneous determination of hydroquinone (HQ) and catechol (CC). The anodic peaks of HQ and CC can be separated well. Owing to the unique properties of MWNTs and special synergistic effect of MWNTs and Co(II)TPP, the modified electrode exhibited a remarkable and stable current response for CC and HQ. The linear ranges for CC and HQ were 1.0–450.0 µmol L^?1 and 0.8–400.0 µmol L^?1 with detection limits of 0.8 µmol L^?1 and 0.5 µmol L^?1, respectively. Furthermore, Co(II)TPP, MWNTs, and Co(II)TPP/MWNTs composite were also used to construct modified electrodes and the electrochemical performances were studied.