聚刚果红修饰玻碳电极的制备及其电催化性能

在含刚果红的硼砂缓冲溶液中,用循环伏安法扫描,在玻碳电极上形成聚合物薄膜.在 -0. 8V~+1. 8V(vsAg/AgCl)的扫描电位范围形成的薄膜具有较高的电活性和稳定性.该电极对抗坏血酸、邻苯二酚的电化学氧化有催化作用,增大了氧化峰电流.催化峰电流与抗坏血酸和邻苯二酚浓度分别在 20 ~1 200mmol/L, 50 ~2 000mmol/L范围内呈良好的线性关系.     

抗坏血酸在PPy-HEImTfa/Pt电极上的电催化氧化及其机理

以铂为基底电极,在1-乙基咪唑三氟乙酸盐(HEImTfa)离子液体中电化学合成导电聚吡咯(PPy),制得PPy-HEImTfa/Pt电极;采用循环伏安法研究了PPy-HEImTfa/Pt电极对抗坏血酸的电催化氧化性能.结果表明:PPy-HEImTfa/Pt电极对0.1mo·lL-1抗坏血酸具有较高的电催化氧化活性,与相同条件下硫酸溶液中在铂表面修饰的聚吡咯(PPy-H2SO4/Pt)电极和裸铂电极相比,其氧化峰电位分别降低了0.10和0.19V,氧化峰电流分别增加了3.0和3.6mA.同时采用原位傅里叶变换红外(insitu FTIR)光谱技术对抗坏血酸在PPy-HEImTfa/Pt电极上的电氧化机理进行了研究,结果表明:抗坏血酸在PPy-HEImTfa/Pt电极上首先被氧化为脱氢抗坏血酸,在水溶液中脱氢抗坏血酸迅速发生水合作用形成水合脱氢抗坏血酸,它进一步水解并发生内酯开环反应生成2,3-二酮古洛糖酸;在较高电位下,部分抗坏血酸最终被氧化成CO2.     

聚乙撑二氧噻吩修饰电极的电化学行为及对抗坏血酸的电催化作用

研究了聚乙撑二氧噻吩修饰电极在水溶液中的电化学行为及对抗坏血酸的电催化作用,实验表明抗坏血酸在聚乙撑二氧噻吩修饰电极上的氧化峰电位为+0.23V,较其在铂电极上的氧化峰电位负移220mV.在1.0×10^-1～1.0×10^-1mol/L浓度范围内,峰电流和抗坏血酸的浓度有线性关系,可用于水果等样品中抗坏血酸的测定。     

抗坏血酸在聚对羟基苯甲酸修饰玻碳电极上的催化电氧化行为

通过循环伏安(CV)制备了聚对羟基苯甲酸(poly-PHB)修饰的玻碳电极. 考察了电极对抗坏血酸(AA)电氧化的催化性能. 结果显示,聚对羟基苯甲酸修饰玻碳电极对AA氧化有很好的电催化作用. 在修饰电极上产生的峰电流比在未修饰电极上产生的氧化峰电流大4倍,氧化峰电位负移205 mV. 氧化峰电流与AA浓度在2.6×10-5～3.68 ×10-4 mol/L范围内呈线性关系,相关系数为0.998 4,检测限为5×10-6 mol/L(S/N=3). 在AA与多巴胺(DA)共存的体系中,能排除DA对抗坏血酸测定的干扰.     

聚灿烂甲酚蓝膜修饰电极测定抗坏血酸的研究

电化学聚合制备了聚灿烂甲酚蓝薄膜修饰玻碳电极,研究了修饰电极对抗坏血酸的电催化氧化作用。结果表明二步法电聚合制备的修饰电极性能优于一步法电聚合,在该电极上抗坏血酸的过电位降低320mV,催化氧化峰电流与抗坏血酸的浓度在2×10-5～5×10-3mol/L范围内呈良好的线性关系,相关系数0.9982。方法可用于药品及食品中抗坏血酸的分析。     

金纳米颗粒在玻碳电极表面的固载及其对抗坏血酸的电催化氧化

采用电化学方法先在玻碳电极(GCE)表面共价键合一末端带有巯基的2-氨基乙硫醇(AET)单层,通过硫-金相互作用将金纳米颗粒(GNP)固载在玻碳电极表面,制备了GNP修饰的GNP-AET/GCE电极.采用X射线光电子能谱和循环伏安法对固载纳米金的玻碳电极的结构和性能进行表征.研究发现:GNP-AET/GCE电极不仅对抗坏血酸具有良好的催化性能,使其氧化过电位由玻碳电极上的0.53V负移到0.33V,氧化峰电流明显增加,而且能将多巴胺和抗坏血酸在玻碳电极上重叠的氧化波分成两个独立的氧化峰,峰间电位差为0.29V,提出了用差分脉冲伏安法在多巴胺共存在测定抗坏血酸的选择性方法.峰电流与抗坏血酸浓度在8.5×10-6～1.0×10-4 mol·L-1之间呈线性关系,其检出限为4.7×10-6 mol·L-1.     

碳纳米管和聚电解质修饰玻碳电极的电化学行为及对芦丁的检测

研究了芦丁和抗坏血酸在碳纳米管与聚电解质复合材料修饰电极(PDDA/SWCNTs/GC)上的电化学行为.循环伏安测试结果表明,在该修饰电极上芦丁的电子传递反应受吸附控制.在碳纳米管和PDDA的共同作用下,芦丁和抗坏血酸的氧化峰电位分离大于200 mV.利用微分脉冲伏安法测定了不同浓度芦丁的电流响应,线性范围为2.5～110μmol.L-1,检出限0.5μmol.L-1.即使抗坏血酸浓度较高时,氧化峰电流与芦丁的浓度仍然呈良好的线性关系.该修饰电极制作简便,可应用于药物中芦丁含量的直接检测.     

石墨烯修饰玻碳电极用于循环伏安法测定抗坏血酸

采用Hummers法制备了纳米石墨烯,并将该纳米材料分散在蒸馏水中得到悬浮液,取5μL的悬浮液滴涂在玻碳电极表面,制备石墨烯修饰电极。用循环伏安法研究了在pH 4.0磷酸盐电解质中,在-0.4～0.8V(vs.Ag/AgCl)电位范围内,抗坏血酸在修饰电极上的电化学行为。结果表明:抗坏血酸在修饰电极上在0.173V处可见明显的氧化峰,且氧化峰电流显著高于在裸玻碳电极上的氧化峰电流;并可有效排除肾上腺素、尿酸、多巴胺等物质的干扰。据此提出了用循环伏安法测定抗坏血酸的方法。抗坏血酸的线性范围为8.00×10-6～1.0×10-3 mol.L-1,检出限(3S/N)为1.0×10-7 mol.L-1。方法用于维生素C片的分析,回收率在96.3%～104.4%之间。     

抗坏血酸在聚对羟基苯甲酸(poly-PHB)修饰玻碳上的电催化

过循环伏安制备了聚对羟基苯甲酸修饰的玻碳电极。考察了该电极对抗坏血酸的电催化性能。结果显示,聚对羟基苯甲酸修饰玻碳电极对抗坏血酸有很好的电催化作用。在修饰后的电极上产生的峰电流比修饰前的电极产生的峰电流大4倍,氧化峰电位负移189 mV。其氧化峰电流与抗坏血酸浓度在2.6×10-5~3.68 ×10-4mol/L范围内呈线性关系,相关性系数为0.9984,检测限为5×10-6 mol/L(S /N = 3)。在AA与UA共存的体系中,能排除多巴胺对抗坏血酸测定的干扰。     

肉桂酸修饰电极同时测定多巴胺和抗坏血酸的研究

用电化学聚合方法制备肉桂酸(CA)修饰的玻碳电极(PCA/GC),研究多巴胺(DA)和抗坏血酸(AA)在修饰电极上的电化学行为.结果表明,在DA和AA共存体系中,DA、AA在PCA/GC电极上氧化峰电流增大且氧化峰电位相差200 mV,据此可同时检测DA和AA.在pH 7.0磷酸盐缓冲液中,DA和AA的氧化峰电流与其浓...     

聚灿烂甲酚蓝修饰玻碳电极的制备及电化学性质

在含灿烂甲酚蓝的磷酸缓冲溶液中,用循环伏安法扫描.在经预处理的玻碳电极上形成了聚合物薄膜.在-0.7V-+0.9V(vsSCE)的扫描电位范围和弱碱性介质中形成的薄膜具有较高电活性和稳定性.制备好的聚灿烂甲酚蓝修饰电极在磷酸缓冲溶液的循环伏安曲线有两对氧化还原峰,峰电位随pH升高而向负电位方向移动.该电极对NADH的电化学氧化有催化作用,使其氧化电位负移了270mV并增大了氧化峰电流.     

Electropreparation of Poly(benzophenone‐4) Film Modified Electrode and Its Electrocatalytic Behavior Towards Dopamine,Ascorbic Acid and Nitrite

The oxidation of benzophenone‐4 (2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid) at glassy carbon electrode gives rise to stable redox active electropolymerized film during repetitive potential cycling between 0 to 1.3 V (Ag/AgCl). Cyclic voltammogram of poly(benzophenone‐4) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 51 mV/pH. The electrocatalytic behavior of poly(benzophenone‐4) film modified electrode towards oxidation of dopamine, ascorbic acid and reduction of nitrite was investigated. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(benzophenone‐4) film compared to bare glassy carbon electrode. For dopamine, the overpotential was reduced about 180 mV. Feasibility of utilizing poly(benzophenone‐4) film coated electrode in analytical estimation of dopamine, ascorbic acid and nitrite was also demonstrated.     

A poly(3-acetylthiophene) modified glassy carbon electrode for selective voltammetric measurement of uric acid in urine sample

A reliable and reproducible method for the determination of uric acid in urine samples has been developed. The method is based on the modification of a glassy carbon electrode by 3-acetylthiophene using cyclic voltammetry. The poly(3-acetylthiophene) modified glassy carbon electrode showed an excellent electrocatalytic effect towards the oxidation of uric acid in 0.1 m phosphate buffer solution (PBS) at pH 7.2. Compared with a bare glassy carbon electrode (GCE), an obvious shift of the oxidation peak potential in the cathodic direction and a marked enhancement of the anodic current response for uric acid were observed. The poly(3-acetylthiophene)/GCE was used for the determination of uric acid using square wave voltammetry. The peak current increased linearly with the concentration of uric acid in the range of 1.25 x 10(-5)-1.75 x 10(-4) M. The detection limit was 5.27 x 10(-7) M by square wave voltammetry. The poly(3-acetylthiophene)/GCE was also effective to determine uric acid and ascorbic acid in a mixture and resolved the overlapping anodic peaks of these two species into two well-defined voltammetric peaks in cyclic voltammetry at 0.030 V and 0.320 V (vs. Ag/AgCl) for ascorbic acid and uric acid, respectively. The modified electrode exhibited stable and sensitive current responses toward uric acid and ascorbic acid. The method has successfully been applied for determination of uric acid in urine samples.     

Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion‐Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH,Dopamine and Ascorbic Acid

Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis.     

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。     

Electrochemical determination of ascorbic acid using the poly-cysteine film-modified electrode

A poly(L-cysteine) thin film was prepared onto electrode surface via electropolymerization. In pH 7.0 phosphate buffer, L-cysteine was oxidized during the cyclic potential sweep between −0.60 and 2.00 V, forming a thin film at the glassy carbon electrode (GCE) surface. The electrochemical behaviors of ascorbic acid at the bare GCE and the poly(L-cysteine) film-coated GCE were investigated. The oxidation peak potential of ascorbic acid shifts to more negative potential at the poly(L-cysteine) film-modified GCE. Moreover, the oxidation peak current significantly increases at the poly(L-cysteine) film-modified GCE. These phenomena indicate that poly(L-cysteine) film shows highly-efficient catalytic activity to the oxidation of ascorbic acid. Based on this, a sensitive and simple electrochemical method was proposed for the determination of ascorbic acid. The oxidation peak current of ascorbic acid is proportional to its concentration over the range from 1.0 × 10⁻⁶ to 5.0 × 10⁻⁴ mol l⁻¹. The limit of detection is evaluated to be 4.0 × 10⁻⁷ mol l⁻¹.     

Highly Sensitive Amperometric Glucose Biosensor Based on Glassy Carbon Electrode with Copper/Palladium Coating

A highly sensitive amperometric glucose biosensor based on immobilizing glucose oxidase in electropolymerized poly(o‐phenylenediamine) film on glassy carbon electrode coated sequentially with copper and palladium layers has been developed. The steady‐state amperometric response to glucose was determined by means of the oxidation of hydrogen peroxide generated by the enzymatic reaction at a potential of either +0.70 or +0.40 V (vs. Ag|AgCl reference). The deposited copper/palladium layer showed great enhancement in the performance of the enzyme electrode, possibly due to its better electrocatalytic activity for hydrogen peroxide oxidation and large surface area. Effects of the relative loading of palladium, enzyme and polymer on the electrode performance were examined in detail. Sensitivity and detection limit for glucose determinations at +0.70 V were about 7.3 μA/mM and 0.1 μM, respectively. A wide linear range up to 6.0 mM glucose could be achieved. Electrode performance was superior to similar works reported in the literature. The response time was less than 2 s and its lifetime was longer than three months. The permeable polyphenylenediamine film also offered good anti‐interference ability to ascorbic acid, uric acid and acetaminophen, especially when a detection potential of +0.40 V was employed.     

聚磺基水杨酸/碳纳米管修饰电极在抗坏血酸共存时测定多巴胺

研究了聚磺基水杨酸/多壁碳纳米管修饰玻碳电极的制备及多巴胺在此修饰电极上的电化学行为, 讨论了修饰条件、扫速、溶液 pH 以及抗坏血酸的干扰对多巴胺在这种复合物电极上响应的影响. 在 pH 7.4 磷酸盐缓冲溶液中, 在1.0×10-3 mol/L 抗坏血酸共存的条件下, 多巴胺氧化峰电流与其浓度在 5×10-7～10-4 mol/L 范围内分段呈线性关系, 检出限为 1.0×10-7 mol/L. 结果表明: 聚磺基水杨酸/多壁碳纳米管修饰电极结合了多壁碳纳米管灵敏度高和聚磺基水杨酸选择性好的优点, 可用于抗坏血酸共存条件下多巴胺的测定.     

Poly(4-amino-1-1'-azobenzene-3, 4'-disulfonic acid) coated electrode for selective detection of dopamine from its interferences

Here, we described a new method for electrochemically selective detection of dopamine (DA). In this report, for the first time, electrochemical polymerization of 4-amino-1-1'-azobenzene-3,4'-disulfonic acid (acid yellow 9 dye (AY)) was carried out onto the surface of glassy carbon (GC) electrode and indium tin oxide coated electrode (ITO) from acidic solution containing AY monomers. A polymerized film of acid yellow on the surface of a glassy carbon electrode was characterized by cyclic voltammetry (CV). The redox response of the poly(AY) film on the GC electrode showed a couple of redox peak in 0.1M sulfuric acid solution and the pH dependent peak potential was -58mV/pH which was close to the Nernst behavior. The poly(AY) film-coated GC electrode (GC/PAY) exhibited excellent electrocatalytic activity towards the oxidations of dopamine (DA) in 0.1M phosphate buffer solution (PBS, pH 7.0) and increased the anodic peak current three time higher than bare GC electrode. GC/PAY did not reduce the considerable overpotential for oxidation of DA when compare to bare GC electrode. However, in contrast to other polymer modified electrode, due to the strong negatively charged back bone of poly(AY) highly repelled the important interference of DA, such as ascorbic acid (AA), uric acid (UA) and reduced form of nicotinamide adenine dinucleotide (NADH) in 0.1M PBS (pH 7.0) and did not showed any response for oxidation of these interferences. This behavior makes the GC/PAY for selective detection of DA in the presence of higher concentrations AA, UA and NADH. Using differential pulse voltammetry the calibration curves for DA were obtained over the range of 1-100muM with good selectivity and sensitivity. The proposed method provides a simple method for selective detection of DA from its interferences.