聚L-精氨酸修饰电极存在下同时测定多巴胺和肾上腺素

用循环伏安法制备了聚L-精氨酸修饰玻碳电极,研究了多巴胺和肾上腺素在修饰电极上的电化学行为,建立了同时测定多巴胺和肾上腺素的新方法。在pH7.5的磷酸盐缓冲溶液中,多巴胺在修饰电极上产生一对氧化还原峰,峰电位分别为0.276V和0.059V;肾上腺素在修饰电极上产生3个氧化峰和一个还原峰,峰电位分别为0.262V、0.121V、-0.126V和-0.316V(对Ag/AgCl电极)。多巴胺和肾上腺素同时存在时ΔEpc=375mV,用还原峰对多巴胺和肾上腺素同时测定的线性范围分别为8.0×10-7~5.0×10-4mol/L和5.0×10-7~5.0×10-5mol/L;检出限分别为3.0×10-7mol/L和1.0×10-7mol/L。大量的抗坏血酸和尿酸不干扰测定,用于人尿液中多巴胺和肾上腺素样品的同时测定,结果满意。     

同时测定多巴胺和肾上腺素的大环镍膜修饰电极

研究了大环镍膜修饰电极对多巴胺和肾上腺素的电化学响应特性；结果表明，该修饰电极对多巴胺和肾上腺素的电极反应具有良好的催化活性，多巴胺和肾上腺素在修饰电极上的氧化电位比在裸铂电极上分别负移了230mV和70mV，使二者的阳极峰得到很好的分离，且灵敏度大为提高；将该修饰电极用于多巴胺和肾上腺素的同时检测，获得满意结果，生物体中的主要干扰物质抗坏血酸和NO2^-等均不干扰测定。     

纳米金/石墨烯修饰电极的制备及其对多巴胺的测定

利用电化学还原方法制备纳米金/石墨烯修饰玻碳电极,研究了多巴胺(DA)在该修饰电极上的电化学行为,建立了电化学测定多巴胺的新方法。结果表明,在磷酸盐缓冲溶液中,此修饰电极对多巴胺的电化学响应具有很好的催化作用。利用差示脉冲伏安技术对多巴胺的电化学氧化进行定量分析,多巴胺的氧化峰电流与其浓度在1.0×10-7～1.0×10-5mol/L范围内呈良好的线性关系,检测限低至4.0×10-8mol/L。该修饰电极适于多巴胺的分析检测。     

聚L-苏氨酸修饰电极对多巴胺和肾上腺素的电催化氧化

利用循环伏安法将L-苏氨酸聚合修饰在玻碳电极表面, 制成聚L-苏氨酸修饰电极. 实验表明, 该电极对多巴胺和肾上腺素都有较好的催化氧化效果. 运用循环伏安法详细研究了修饰电极的电化学性质. 在pH 2.5的磷酸盐缓冲溶液(PBS)中, 肾上腺素的电子传递系数为0.51, 表观反应速率常数为1.33 s-1; 在pH 7.5的PBS中, 多巴胺在电极上产生一对氧化还原峰, 多巴胺在电极上的电子传递系数为0.60, 表观反应速率常数为0.92 s-1. 该修饰电极对多巴胺和肾上腺素能够进行同时测定, 还原峰电流与多巴胺和肾上腺素浓度分别在1.0×10-6-5.0×10-4 mol·L-1和3.0×10-6-1.0×10-4 mol·L-1范围内呈现良好的线性关系.     

聚色氨酸膜电极相敏交流伏安法测定肾上腺素

研究了聚色氨酸膜电极的制备及其肾上腺素在该修饰电极上的相敏交流伏安特性,建立了相敏交流伏安法测定肾上腺素的电化学分析法。在pH 6.0的磷酸盐缓冲溶液中,肾上腺素的相敏交流伏安氧化峰电位在298 mV,线性响应范围为1.05×10-6~3.98×10-5mol/L,检出限为8.40×10-7mol/L。用于药剂中肾上腺素的测定,相对标准偏差小于3.84%,加标回收率为99%~104%,多巴胺、抗坏血酸和尿酸不干扰。     

聚溴酚蓝修饰电极对多巴胺的电催化作用及伏安测定

在含溴酚蓝的磷酸缓冲液中,用循环伏安法在玻碳电极上制备聚合物薄膜。采用循环伏安法研究多巴胺在聚溴酚蓝修饰电极上的电化学行为,实验结果表明聚溴酚蓝修饰电极对多巴胺的氧化具有良好的电催化性能。在1．0～10μmol／L范围内,多巴胺浓度与其线性扫描伏安峰电流呈良好的线性关系,相关系数为0．9999,平均回收率为100．2％。该方法可用于盐酸多巴胺注射液中的多巴胺的测定。     

银掺杂聚L-缬氨酸修饰电极的制备及对肾上腺素的测定

利用循环伏安法将银和L-缬氨酸聚合修饰在玻碳电极表面,制成银掺杂聚L-缬氨酸修饰电极(Ag-PLV/GCE),研究了肾上腺素在该电极上的电化学行为,建立了电化学测定肾上腺素的新方法.在pH3.5的磷酸盐缓冲溶液中,扫描速率为40 mV/s时,肾上腺素在修饰电极上产生一对氧化还原峰,Epa=0.422 V,Epc=0.3...     

在抗坏血酸存在下用L-赖氨酸修饰玻碳电极测定多巴胺

采用电化学氧化法制备了L-广赖氮酸单分子层修饰玻碳电极，研究了多巴胺（DA）和抗坏血酸（AA）在该电极上的电化学行为。结果表明，L-广赖氨酸单分子层修饰玻碳电极不仅能改善多巴胺和抗坏血酸的电化学行为，而且能将多巴胺和抗坏血酸二者在裸电极上的完全重叠的单氧化峰分开成为两个完全独立的氧化峰，循环伏安（CV）图上峰间距为507mV，差分脉冲伏安（DPV）图上峰间距为460mV，由此可实现在AA的共存下对样品中的DA进行选择性测定。     

多巴胺在聚2,4,6-三甲基吡啶修饰电极上的电化学行为

用循环伏安法制备了聚 2 ,4 ,6 三甲基吡啶修饰玻碳电极 ,研究了神经递质多巴胺在该聚合物薄膜修饰电极上的电化学行为。实验结果表明 :在pH 7.4磷酸盐缓冲溶液中 ,多巴胺在该修饰电极上的线性范围为4 .0× 10 -6～ 1.0× 10 -5mol/L。该修饰电极对抗坏血酸无响应 ,从而可有效消除其对多巴胺测定的干扰     

碳纳米管/聚吡咯修饰电极用于液相色谱测定帕金森大鼠脑中神经递质

制备了碳纳米管/聚吡咯复合修饰电极,研究了多巴胺等单胺类神经递质在该修饰电极上的电化学行为.将此修饰电极作为电化学检测器,与高效液相色谱联用,测定了脑中7种神经递质及其代谢产物.结果表明:去甲肾上腺素、肾上腺素、多巴胺和5-羟色胺的线性范围为5.0×10(-10)～1.0×10(-5)mol/L;3,4-二羟基苯乙酸,...     

柠檬酸修饰(CA/GC)电极对多巴胺(DA)和肾上腺素(EP)同时检测

应用电沉积方法制备柠檬酸修饰电极(CA/GC), 差分脉冲法研究多巴胺(DA)和肾上腺素(EP)在该修饰电极上的电化学行为．结果表明, 两样品DA、EP在该电极的还原峰电位差380 mV, 而抗坏血酸(AA)在此电位区无还原峰, 因此可实现该修饰电极对DA和EP的同时检测, 而且高浓度AA不发生干扰．在pH 6.0的磷酸盐缓冲液中, DA和EP还原峰电流与其浓度分别在1.0×10-6 ~ 6.0×10-5 mol•L-1和2.0×10-6 ~ 6.0×10-5 mol•L-1 范围内呈线性关系．CA/GC电极制备简单, 重现性好, 可望用于多巴胺针剂(DA)和肾上腺素针剂(EP)的同时检测     

Enhanced Electrocatalytic Activity of Ni‐CNT Nanocomposites for Simultaneous Determination of Epinephrine and Dopamine

A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM^?1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples.     

A novel and simple biosensor based on poly(indoleacetic acid) film and its application for simultaneous electrochemical determination of dopamine and epinephrine in the presence of ascorbic acid

A novel and simple biosensor based on poly(indoleacetic acid) film-modified electrode (PIAA/CPE) was fabricated by electrochemical polymerization of indoleacetic acid on a carbon paste electrode (CPE) through cyclic voltammetry. The resulting electrode was characterized by scanning electron microscopy, and the electrochemical behaviors of dopamine (DA) and epinephrine (EP) at the electrode were studied. It was illustrated that PIAA/CPE had excellent electrochemical catalytic activities toward DA and EP. The anodic peak currents (I _pa) were dramatically enhanced by about seven-fold for DA and ten times for EP at PIAA/CPE. Thus, the determinations of DA and EP were carried out using PIAA/CPE successfully. The linear responses were obtained in the range of 3.0?×?10^?7～7.0?×?10^?4 and 1.0?×?10^?6 ～8.0?×?10^?4 mol L^?1 with the detection limits (3σ) of 1?×?10^?7 and 4?×?10^?7 mol L^?1 corresponding with DA and EP, respectively. Moreover, the cathodic peaks of DA and EP were well-separated with a potential difference about 325 mV in pH 5.3 phosphate-buffered saline, so simultaneous determination of DA and EP was carried out in this paper. Additionally, the interference studies showed that the PIAA/CPE exhibited excellent selectivity in the presence of ascorbic acid (AA). With good selectivity and sensitivity, the present method has been successfully applied to the determination of DA and EP in pharmaceutical samples.     

Uracil Grafted Carbon Electrode:Electrocatalytic Behavior of Tryptophan,Tyrosine, Catecholamine and Related Compounds

基于尿嘧啶作为一种碱基,具备一定的分子识别能力,制备了一种新颖的尿嘧啶共价修饰电极,用X射线光电子能谱和电化学方法进行了表征,并研究了酪氨酸、色氨酸、儿茶酚胺（如多巴胺,肾上腺素,去甲肾上腺素）及相关的化合物尿酸、抗坏血酸在该电极上的电化学行为,获得相应的氧化电位、电流灵敏度、线性范围和检测限等信息。其中,色氨酸检测线性范围：1.8 - 120 mM,检测限（s/n=3）：0.8 mM;酪氨酸检测线性范围：1.8 - 89mM,检测限（s/n=3）：0.8 mM。实验表明,尿嘧啶修饰电极能催化氧化上述电活性物质,但催化能力不同,据此,我们讨论了尿嘧啶与上述物质的相互作用,详细探讨了催化机理,扩展了对基于分子识别的传感器的研究。     

Caffeic Acid‐Modified Glassy Carbon Electrode for the Simultaneous Determination of Epinephrine and Dopamine

A stable electroactive thin film of poly(caffeic acid) has been deposited on the surface of a glassy carbon electrode by potentiostatic technique in an aqueous solution containing caffeic acid. The electrochemical behaviors of epinephrine (EP), dopamine (DA) and their mixture have been studied. The oxidation peaks of EP and DA at the poly(caffeic acid) modified glassy carbon electrode appeared at the same potential, but the anodic peak currents of the mixture of DA and EP were almost equal to the sum of individual anodic peak currents of EP and DA, whereas the cathodic peak current only related to the concentration of DA under appropriate condition. Base on these, the simultaneous voltammetric measurement of EP and DA at the poly(caffeic acid) film modified electrode has been developed. Ascorbic acid (AA) had no interference with the simultaneous determination of EP and DA under the same condition because the oxidative peak potential of AA was less than those of DA and EP. The modified electrode has been satisfactorily used for the simultaneous determination of EP and DA in real samples.     

Immobilization of DNA on a glassy carbon electrode based on Langmuir–Blodgett technique: application to the detection of epinephrine

A double-stranded (ds) DNA-octadecylamine Langmuir–Blodgett film was attached to the surface of glassy carbon electrode (GCE) to create a novel voltammetric sensor (DNA-LB/GCE) for epinephrine (EP). Atomic force microscopy and electrochemical impedance spectroscopy were employed to study the characteristic of the DNA-LB film. The electrochemical behavior of EP at the modified electrode was investigated in pH 6.0 phosphate buffer solutions by cyclic voltammetry and amperometric methods. Compared with bare GCE, the DNA-LB/GCE sensor demonstrated an electrocatalytic effect on the oxidation of EP. In addition, the sensor shows excellent selectivity for EP detection, being free of interference from excess ascorbic acid and uric acid, and the method was also applied successfully to detect EP in the human urine samples.     

Electroanalysis and simultaneous determination of dopamine and epinephrine at poly(isonicotinic acid)-modified carbon paste electrode in the presence of ascorbic acid

A carbon paste electrode modified with electropolymerized fills of isonicotinic acid was developed.The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine(DA)and epinephrine(EP).Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution(PBS)and the character was used for the detection DA and EP simultaneously.The peak currents increase linearly with DA and EP concentration over the range of 8.0×10-5 to 7.0×10-4 mol/L and 5.0×10-6 to 1.0×10-4 mol/L with detection limits of 2 × 10-5 and 1×10-6 mol/L,respectively.The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid(AA).     

银掺杂聚L-酪氨酸修饰电极同时测定多巴胺、肾上腺素和抗坏血酸

用循环伏安法制备银掺杂聚L-酪氨酸修饰玻碳电极,研究了多巴胺、肾上腺素和抗坏血酸在其电极上的电化学行为,建立了同时测定多巴胺、肾上腺素和抗坏血酸的新方法。当3种组分共存时,在磷酸盐缓冲溶液(pH6.0)中,扫描速率为140mV/s,多巴胺和肾上腺素在修饰电极上分别产生还原峰,峰电位分别为0.198和-0.205V,多巴胺和肾上腺素氧化峰重叠,峰电位为0.313V(vs.Ag/AgCl);抗坏血酸产生一个氧化峰,峰电位0.108V(vs.Ag/AgCl)。多巴胺和肾上腺素的ΔEpc=0.403V,抗坏血酸的氧化峰与多巴胺和肾上腺素的ΔEpa=0.205V,用还原峰和氧化峰可同时测定多巴胺、肾上腺素和抗坏血酸,3种组分同时测定的线性范围分别为5.0×10-6～1.0×10-4mol/L,8.0×10-6～1.0×10-4mol/L和3.0×10-5～1.0×10-3mol/L;检出限分别为5.0×10-7,8.0×10-7和5.0×10-6mol/L。本方法用于人尿液中多巴胺、肾上腺素和抗坏血酸的同时测定,结果满意。     

2,3-Dimercaptosuccinic acid self-assembled gold electrode for the simultaneous determination of epinephrine and dopamine

Simultaneous determination of epinephrine(EP)and dopamine(DA)at 2,3-dimercaptosuccinic acid(DMSA)modified electrode was studied.The oxidation peaks of the mixture of EP and DA appeared at the same potential,but the cathodic peak currents were only linear to the concentration of DA,whereas the anodic peak currents were equal to the sum of individual anodic peak currents of EP and DA.Therefore,a novel electrochemical method for the simultaneous determination of EP and DA at a DMSA modified electrode(DMSA/A...