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.     

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.     

Sensitive Adsorption Stripping Voltammetric Determination of Reserpine by a Glassy Carbon Electrode Modified with Multi-Wall Carbon Nanotubes

Adsorption stripping voltammetry, a very sensitive electroanalytical method, was employed to determine reserpine, a kind of anti-hypertensive drug. In 0.1M phosphate buffer with a pH of 6.0, reserpine was accumulated at a multi-wall carbon nanotubes (MWNT)-modified glassy carbon electrode (GCE) surface under the condition of open-circuit. In the following anodic sweep from 0.20 to 1.00V, reserpine, adsorbed at the MWNT-modified GCE surface, was oxidized and yielded a sensitive oxidation peak at 0.64V. Due to its unique structure and extraordinary properties, MWNT shows a ten times higher accumulation efficiency toward reserpine, compared with a bare GCE. Hence, the amount of reserpine at the MWNT-modified GCE surface increases significantly, and finally the oxidation peak current improves greatly. The experimental conditions, such as supporting electrolyte, pH value, the amount of MWNT-DHP suspension, accumulation time and scan rate, were optimized for the measurement of reserpine, and a sensitive electroanalytical method was proposed for reserpine determination. The oxidation peak current varies linearly with the concentration of reserpine over the range of 2×10^–8 to 1×10^–5M, and the detection limit is 7.5×10^–9M after 4min open-circuit accumulation. The relative standard deviation at 1×10^–6M reserpine was about 4.7% (n=7), indicating excellent reproducibility. This new method was successfully demonstrated with reserpine injections and tablets.     

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     

Electrochemical Determination of 10-Hydroxycamptothecin Using a Multi-Wall Carbon Nanotube-Modified Electrode

We report a sensitive and convenient voltammetric method for the direct determination of 10-hydroxycamptothecin (HCPT). At a multi-wall carbon nanotube (MWNT)-modified electrode, HCPT yields a very sensitive and well-shaped oxidation peak, which can be used as analytical signal for HCPT determination. Compared with the poor electrochemical signal at the unmodified GCE, the electrochemical response of HCPT at the MWNT-modified GCE was greatly improved, as confirmed by the significant peak current enhancement. This result indicates that the MWNT-modified GCE has great potential in the sensitive determination of HCPT. Based on this, a very sensitive and simple electrochemical method was proposed for HCPT determination after all the experimental parameters were optimized. The newly-proposed method possesses very low detection limit (2 × 10⁻⁹ mol L⁻¹) and wider linear range (from 1 × 10⁻⁸ to 4 × 10⁻⁶ mol L⁻¹). Rapid and simple sample analysis is another advantage. Finally, this method was successfully demonstrated using HCPT drugs.     

土霉素在碳纳米管修饰电极上的电化学行为研究及其测定

研究了土霉素 (OTC)在 MWNT修饰电极上的伏安行为 ,优化了测定参数 ,在此基础上建立了一种直接测定土霉素的电化学分析方法。还原峰电流与土霉素的浓度在 2× 1 0 - 7～ 5× 1 0 - 5mol/L之间有很好的线性关系。开路富集 2 min后的检出限为 5× 1 0 - 8mol/L。用此方法测定了土霉素片剂中土霉素的含量 ,结果满意     

多壁碳纳米管修饰玻碳电极测定多巴酚丁胺的研究

研究了多巴酚丁胺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多巴酚丁胺的电化学方法。在0.3mol·L-1H2SO4底液中,氧化峰电位为0.57V(vs.Ag/AgCl),峰电流与多巴酚丁胺的浓度在5.0×10-8～1.0×10-5mol·L-1范围内呈良好的线性关系。该法的检出限为3.0×10-8mol·L-1。平均回收率为99.15%。1.0×10-5mol·L-1多巴酚丁胺平行测定8次的标准偏差为4.8%。用拟定的方法测定了多巴酚丁胺注射液中多巴酚丁胺的含量,结果满意。     

碳纳米管修饰电极对多巴胺和肾上腺素的电分离及同时测定

研究了多巴胺 (DA)和肾上腺素 (EP)在多壁碳纳米管 (MWNT)修饰电极上的电化学性质 ,发现该修饰电极对神经递质DA和EP有显著的增敏和电分离作用。还原峰电位差达ΔEp=390mV ,可同时测定DA和EP。DA和EP的还原峰电流与其浓度分别在 2 .0× 10 -6～ 1.0× 10 -3 mol/L和 1.0× 10 -6～ 1.0× 10 -3 mol/L浓度范围内呈良好的线性关系 ;方法的检出限分别为 1× 10 -6mol/L和 5× 10 -7mol/L。由于抗坏血酸 (AA)在MWNT修饰电极上的氧化是不可逆的 ,因此利用还原峰进行测定 ,消除了AA对DA和EP的干扰     

多壁碳纳米管-Nafion复合膜修饰玻碳电极测定硝苯地平的研究

研制了以Nafion分散羧基化多壁碳纳米管的化学修饰电极(Nafion-MWCNTs/GC),研究了硝苯地平(NIF)在修饰电极上的电化学行为和测定方法。实验结果表明,在0.1mol/LNH3-NH4Cl(pH9.6)溶液中,Nafion-MWCNTs/GC,对NIF具有明显的催化和增敏作用,还原峰电位由-0.85V(裸电极)正移到-0.75V(vs.AgCl/Ag)(修饰电极),灵敏度增加约7倍。对各种实验条件进行了优化。定量测定的线性范围为2.5×10-7~4.5×10-5mol/L,r为0.9974;检出限为8.0×10-8mol/L。探讨了NIF在Nafion-MWCNTs/GC上的电极过程和反应机理,测得在本体系中参与反应的质子数和电子转移数均为4,电子转移系数α为0.41。对NIF药片进行了测定,回收率为94.5%~101.0%。     

Electrochemical Characterization of Polymerized Cresol Red Film Modified Glassy Carbon Electrode and Separation of Electrocatalytic Responses for Ascorbic Acid and Dopamine Oxidation

A cresol red modified glassy carbon electrode was prepared using an electrochemical method. The cyclic voltammograms of the modified electrode indicate the presence of a couple of well-defined redox peaks, and the formal potential shifts in the negative direction with increasing solution pH. The modified electrode exhibits high electrocatalytic activity toward ascorbic acid oxidation, with an overpotential of 300 mV less than that of bare glassy carbon electrodes, and drastic enhancement of the anodic currents. The calibration graph obtained by linear sweep voltammetry for ascorbic acid is linear in the range of 50∼500 µM. The electrode markedly enhances the current response of dopamine and can separate the electrochemical responses of ascorbic acid and dopamine. The separation between the anodic peak potentials of ascorbic acid and dopamine is 190 mV by cyclic voltammetry. The linear sweep voltammetric peak currents for dopamine in the presence of 2 mM ascorbic acid vary linearly with a concentration of between 10 and 100 µM.     

异烟肼在多壁碳纳米管修饰碳糊电极上的电化学行为及其应用

通过研究异烟肼在多壁碳纳米管修饰碳糊电极上的电化学行为建立了测定异烟肼的电化学方法。在pH6.8的磷酸氢二钠–柠檬酸缓冲溶液中,异烟肼在–1.114 V处能产生一明显还原峰,异烟肼在修饰电极上的反应是受吸附控制的2质子、2电子电极反应过程。研究发现还原峰峰电流大小与异烟肼浓度在5.00×10~(-3)~5.00 mmol/L内呈良好的线性关系,相关系数r=0.997 0,方法检出限为1.70×10~(-3) mmol/L,测定结果的相对标准偏差为3.11%(n=5),回收率为97.6%~103.6%。该方法简单、灵敏,精密度高,可应用于样品中异烟肼的测定。     

蒙脱土修饰电极上某些神经递质的电化学行为

采用不同电化学方法对神经递质多巴胺（ＤＡ）在蒙脱土修饰电极上的行为进行了研究，结果发现，蒙脱土修饰膜地ＤＡ有明显的富集作用。在ＰＨ７．４时，ＤＡ强烈地富集在蒙脱土膜内，并显示完成的伏安响应而抗坏血酸（ＡＡ）和ＤＡＲ的代谢产物３，４－二羟基苯乙酸（ＤＯＰＡＣ）则无任何响应。采用计时库仑法测定了ＤＡ在蒙脱土膜内的表观扩散系数为２．３×１０＾－９ｃｍ＾２／ｓ，并计算了异相速率常数为２．７×１０＾－６ｃｍ     

Electrochemical Determination of Dopamine Using a Novel Perylenediimide-Derivative Modified Carbon Paste Electrode

A novel perylenediimide derivative, N,N′-bis(4-{2-[2-(2-methoxyethoxy ethoxy]ethoxy}phenyl)-3,4:9,10-perylene tetracarboxydiimide, was utilized for the modification of a carbon paste electrode to develop a practical and sensitive electrochemical sensor for dopamine detection. The effects of experimental parameters (modifier amount, pH, and scan rate) on the dopamine peak current were examined. The performance of the modified carbon paste electrode was evaluated under optimum conditions and 4.6-fold increase in the peak current was obtained compared to an unmodified carbon paste electrode. The linear range was between 1 and 100?µM dopamine and the limits of detection and quantification were 0.011 and 0.036?µM, respectively. The developed sensor was also applied for the quantitative determination of dopamine in injections and promising results were obtained.     

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。     

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。     

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.     

Determination of Dopamine in the Presence of Ascorbic Acid Using a Poly(Amidosulfonic Acid) Modified Glassy Carbon Electrode

A glassy carbon electrode (GCE) was modified with electropolymerized films of amidosulfonic acid in pH 7.0 phosphate buffer solution (PBS) by cyclic voltammetry (CV). The modified electrode showed an excellent electrocatalytical effect on the oxidation of dopamine (DA). In pH 7.0 PBS, the anodic peak current increased linearly with the concentration of DA in the range of 5.0×10^–7 1.0×10^–4moldm^–3, with a correlation coefficient of 0.9932, and a detection limit (S/N=3) of 1.0× 10^–7moldm^–3. The relative standard deviation of 10 successive scans was 2.5% for 1.0×10^–6moldm^–3 DA. The interference of ascorbic acid (AA) with the determination of DA could be eliminated because of the very distinct attracting interaction between DA cations and the negatively poly(amidosulfonic acid) film in pH 7.0 PBS. The proposed method exhibited good recovery and reproducibility.     

盐酸伪麻黄碱在多壁碳纳米管修饰玻碳电极上的电催化氧化及其电化学动力学性质

盐酸伪麻黄碱;碳纳米管修饰电极;电催化氧化;电化学动力学     

基于复合膜修饰玻碳电极对黄嘌呤的选择性测定

制备了一种新型电化学传感器--聚2,2-联吡啶(Pbpy)/1-苯基-3-甲基-4-(α-呋喃甲酰基)-5-吡唑啉酮(HPM-α-FP)/玻碳(GC)复合膜修饰电极。 运用循环伏安法和脉冲伏安法研究了药物分子黄嘌呤(XN)的电化学行为及反应机理。 与裸GCE和Pbpy/GCE电极相比,复合修饰电极Pbpy/HPM-α-FP/GCE测定XN的氧化峰电流和检测灵敏度均有显著提高,表明聚2,2-联吡啶与酰基吡唑啉酮产生了协同增效作用。 当pH=8,扫速为100 mV/s的条件下,氧化峰电流与黄嘌呤浓度在6×10-7～1×10-5 mol/L和1×10-5～1×10-4 mol/L之间均呈现良好的线性关系,检出限为1×10-8 mol/L。 该修饰电极可用于共存尿酸(UA)、抗坏血酸(AA)体系及实际样品的黄嘌呤含量测定。     

阿霉素在多壁碳纳米管膜电极上的电化学行为及其分析研究

报道了一种多壁碳纳米管(MWNT)膜电极的制备方法。研究了阿霉素(ADM)在多壁碳纳米管膜电极上的电化学行为。优化了测定阿霉素的各实验参数,实验证实,ADM浓度在2.0×10-8～1.0×10-5mol/L之间其还原峰电流与浓度有良好的线性关系。富集4min后检测,本法的检出限为5.0×10-9mol/L。用此膜电极测定了病人服用阿霉素后尿样中阿霉素的浓度,取得了满意的结果。