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。     

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...     

The nano-Au self-assembled glassy carbon electrode for selective determination of epinephrine in the presence of ascorbic acid

Gold nanoparticles were self-assembled to the modified glassy carbon electrode (GC) with cysteamine (CA) to prepare the nano-Au/CA/GC modified electrode. The electrochemical behavior of epinephrine (EP) on the modified electrode was explored with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Epinephrine gave a pair of redox peaks at E_pa = 0.190 mV and E_pc = −0.224 mV (versus SCE), respectively. The nano-Au/CA/GC modified electrode shows an excellent electrocatalytic activity for the oxidation of EP. The modified electrode could be used to determine EP in the presence of ascorbic acid (AA). The response of catalytic current with EP concentration shows a linear relation in the range of 1.0 × 10⁻⁷ to 5.0 × 10⁻⁴ mol L⁻¹ with the correlation coefficient of 0.998. The detection limit is 4.0 × 10⁻⁸ mol L⁻¹. The modified electrode exhibited a good reproducibility, sensitivity and stability for the determination of EP injection.     

石墨烯/铂纳米粒子杂化膜测定肾上腺素

利用循环伏安法制备了石墨烯/铂纳米粒子杂化膜修饰电极,并利用该修饰电极研究了肾上腺素（EP）的电化学行为,建立了测定肾上腺素的电化学方法。 分别利用扫描电子显微镜（SEM）和循环伏安法对电极表面的形貌和电化学性能进行了表征。 试验优化了修饰电极制备过程中影响电极性能的条件和EP的测定条件。 试验结果表明,石墨烯/铂纳米粒子修饰电极对肾上腺素有明显的电催化作用。 在pH=5.0的柠檬酸 磷酸氢二钠缓冲溶液中,EP的氧化峰电流与其浓度在4.4×10-8~2.2×10-6 mol/L的范围内呈良好的线性关系。 线性方程为ipa(10 μA)=0.0753c(mol/L)+3.7653×10-5,r=0.9989,检出限为2.2×10-9 mol/L（S/N=3）。 修饰电极表具有良好的重现性,可用于实际样品的测定。     

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     

Electrochemical Oxidation of Epinephrine and Uric Acid at a Layered Double Hydroxide Film Modified Glassy Carbon Electrode and Its Application

Increasing attention has been paid to layered double hydroxide (LDH) film modified electrode attributing to its desirable properties for fabrication of electrochemical sensor. In this paper, the Zn‐Al LDH film modified glassy carbon electrode was characterized by electrochemical methods. The enhanced electrocatalytic currents and well‐separated potentials for epinephrine (EP) and uric acid (UA) were observed at the as‐prepared electrode. Under selected condition, the differential pulse voltammetry response of the modified electrode to EP (or UA) shows a linear concentration range of 0.5 μM to 0.3 mM (or 2 μM to 0.4 mM) in the presence of 10.0 μM UA (or 20.0 μM EP). At a signal‐to‐noise ratio of 3, the calculated limits of detection are 0.13 μM and 0.66 μM, respectively. The proposed method has been performed to successfully detect EP and UA in analysis of real samples, such as in EP injection solution and human urine samples.     

番红花红聚合膜修饰电极及其应用

研究了番红花红(SFR)在玻碳电极表面聚合过程及聚合条件。SFR聚合膜对于肾上腺素(EP)的氧化能够起到明显的电催化作用。分别利用循环伏安法(CV)、差分脉冲法(DPV)、计时电流法研究了EP在pH7.4的磷酸缓冲溶液中的线性关系,发现其浓度分别在2.0×10-6～9.0×10-6mol/L、1.0×10-5～1.0×10-3mol/L(CV),2.0×10-5～4.0×10-4mol/L(DPV),2.0×10-6～5.0×10-6mol/L(计时电流法)范围内呈良好的线性关系,该电极已用于实际样品测定。     

二茂铁/L-半胱氨酸修饰电极的电化学行为及电催化性能

利用配对试剂将二茂铁酰胺键合在L-半胱氨酸自组装单层膜(SAM)表面, 制成稳定的二茂铁/L-半胱氨酸修饰电极, 该电极在pH 7.0的磷酸盐缓冲液中有一对很好的氧化还原峰. 运用循环伏安法和交流阻抗谱详细研究了修饰电极的电化学行为, 测得电子转移系数为0.66, 表观电极反应速率常数为6.86 s-1. 该修饰电极对肾上腺素有很好的催化作用, 峰电流与肾上腺素浓度在2.0×10-7～1.0×10-5 mol·dm-3范围内呈现良好的线性关系.     

A novel poly(taurine) modified glassy carbon electrode for the simultaneous determination of epinephrine and dopamine

A novel taurine modified glassy carbon electrode was prepared by electropolymerization method. The electrochemical behaviors of epinephrine (EP) and dopamine (DA) at the modified electrode were studied by cyclic voltammetry. The modified electrode exhibited enhanced sensitivity and excellent electrochemical discrimination to DA and EP. The cathodic peaks of the two species were well-separated with a potential difference of about 390 mV, so the poly(taurine) modified electrode was used for simultaneous voltammetric measurement of EP and DA by differential pulse voltammetry. Under the optimum conditions, the cathodic peak currents were linear to concentrations of EP and DA in the range of 2.0 × 10⁻⁶ to 6.0 × 10⁻⁴ mol L⁻¹ and 1.0 × 10⁻⁶ to 8.0 × 10⁻⁴ mol L⁻¹, respectively. The detection limits for EP and DA were 3.0 × 10⁻⁷ and 1.0 × 10⁻⁷ mol L⁻¹, respectively. Because the oxidation of ascorbic acid (AA) is an irreversible reaction at modified electrode, the interference of AA for determining EP and DA was eliminated. The modified electrode has been satisfactorily used for the simultaneous determination of EP and DA in pharmaceutical injections.     

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.     

Cyclic Voltammetry Determination of Epinephrine with a Nano—gold Modified Glassy Carbon Electrode in the Presence of High Concentration Ascorbic Acid

As we know, there are usually some problems in electrochemical analysis with bare electrode to detect neurotransmitters. One is low electron transfer rate and the other is interfering compounds, such as ascorbic acid. So some kinds of modified electrodes have been successfully employed to promote the efficiency of electrochemical analysis1-4, such as Nafion modified electrode5,6 and SAM modified electrode7. They can attract positively-charged neurotransmitters while repulse negatively-cha…     

用修饰电极导数伏安法同时测定多巴胺和肾上腺素

研究了２,６－吡啶二甲酸在玻碳电极上电化学聚合的实验条件及修饰电极的电化学特性,发现该聚合物膜修饰电极对多巴胺和肾上腺素的电化学氧化有显著的催化作用,而对抗坏血酸等阴离子没有响应。利用在修饰电极上循环伏安阴极过程多巴胺和肾上腺素的峰电位不同,采用阴极化导数伏安法可同时测定多巴胺和肾上腺素。     

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.     

Selective Voltammetric Detection of Epinephrine in the Presence of Ascorbic Acid at Poly(4-Methoxyphenol)-Modified Electrode1

A gold electrode was modified with electropolymerized films of 4-methoxyphenol by its oxidative polymerization from an alkaline solution by cyclic voltammetry. The modified electrode was then used to determine epinephrine (EP) in the presence of a high concentration of ascorbic acid (AA) by differential pulse voltammetry. The peak positions as well as relative sensitivity EP/AA were affected by the potential window used for the polymerization. For polymerization between 0 and 1.3 V, the peak potentials recorded in a phosphate buffer solution (pH = 7.2) were 516 and 312 mV vs. Ag/AgCl for EP and AA, respectively. In addition the effects of pH and the type of electrolyte on the linearity range and detection limit are investigated. The detection limit for 3s-test is 0.1 M. The high selectivity and sensitivity for epinephrine was found to be due to charge discrimination/analyte accumulation.     

Selective determination of epinephrine in the presence of ascorbic acid and uric acid by electrocatalytic oxidation at poly(eriochrome black T) film-modified glassy carbon electrode.

An electropolymerized film of eriochrome black T (EBT) has been prepared at a glassy carbon electrode (GCE) by cyclic voltammetry (CV). The poly(EBT) membrane at GCE exhibits an excellent electrocatalytic activity towards the oxidation of epinephrine (EP), ascorbic acid (AA) and uric acid (UA) in acidic solution and reduced the overpotential for the oxidation of EP. The poly(EBT)-coated electrode could separately detect EP, AA and UA in their mixture with the potential differences of 180 and 160 mV for EP-AA and UA-EP, respectively, which are large enough to allow for determination of EP in the presence of AA and UA. Using differential pulse voltammetry, the peak current of EP recorded in pH 3.5 solution was linearly dependent on EP's concentration in the range of 2.5 - 50 microM. Due to its good selectivity and stability, the polymer-coated GCE was successfully applied to the determination of EP in real samples.     

Electrochemical Characteristics of Poly(<Emphasis Type="Italic">o</Emphasis>-Aminobenzoic Acid) Modified Glassy-Carbon Electrode and Its Electrocatalytic Activity towards Oxidation of Epinephrine

Poly(o-aminobenzoic acid) (o-ABA) film is deposited on glassy-carbon electrode (GCE) by electropolymerization in pH 7.0 phosphate buffer solution (PBS). Electrochemical behavior of modified electrode is investigated by electrochemical impedance spectroscopy (EIS), different pulse voltammetry (DPV), and cyclic voltammetry (CV). The results indicate that there is a greater resistance during the electron transfer process in poly(o-ABA) film than in bare GCE for the redox of [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻. Further research indicates that epinephrine (EP) can be strongly absorbed on the surface of the poly(o-ABA) film-modified electrode. The modified electrode shows an excellent electrocatalytical activity on EP oxidation. The EP cathodic peak potential shifts negatively with a slope of −53.5 mV/pH, indicating that equal amounts of proton and electron are involved in the electrode reaction process. In pH 7.0 PBS, the peak current of EP and the concentration has a linear relationship from 0 to 65 μM by amperometric current-time curve. __________ From Elektrokhimiya, Vol. 41, No. 9, 2005, pp. 1059–1065. Original English Text Copyright ? 2005 by Cheng, Jin, Zhang. The text was submitted by the authors in English.     

Sensing epinephrine with an ITO electrode modified with an imprinted chitosan film containing multi-walled carbon nanotubes and a polymerized ionic liquid

We report on a sensor for epinephrine (EP) that is based on an ITO electrode modified with multi-walled carbon nanotubes pre-coated with a polymerized ionic liquid (PIL-MWNTs). A chitosan film was then electrodeposited on the ITO electrode in the presence of EP (the template) and the PIL-MWNTs. This film acts as an excellent recognition matrix due to its excellent film-forming ability and the many functional groups that favor hydrogen bond formation with the target (EP). The PIL-MWNTs, in turn, can improve the sensing performance due to their good electrical conductivity, high dispersity, and large surface area. The imprinted films were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, and thermogravimetric analysis. The electrochemistry of the imprinted electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry and chronoamperometry. The response to EP is linear in the 0.2 μM to 0.67 mM concentration range, and the detection limit is as low as 60 nM (at an S/N of 3). The electrode is reusable and offers good reproducibility and stability.

Selective Electrochemical Epinephrine Sensor Using Self‐Assembled Monomolecular Film of 1,8,15,22‐Tetraaminophthalocyanatonickel(II) on Gold Electrode

This article describes the highly sensitive and selective determination of epinephrine (EP) using self‐assembled monomolecular film (SAMF) of 1,8,15,22‐tetraamino‐phthalocyanatonickel(II) (4α‐Ni^IITAPc) on Au electrode. The 4α‐Ni^IITAPc SAMF modified electrode was prepared by spontaneous adsorption of 4α‐Ni^IITAPc from dimethylformamide solution. The modified electrode oxidizes EP at less over potential with enhanced current response in contrast to the bare Au electrode. The standard heterogeneous rate constant (k°) for the oxidation of EP at 4α‐Ni^IITAPc SAMF modified electrode was found to be 1.94×10^?2 cm s^?1 which was much higher than that at the bare Au electrode. Further, it was found that 4α‐Ni^IITAPc SAMF modified electrode separates the voltammetric signals of ascorbic acid (AA) and EP with a peak separation of 250 mV. Using amperometric method the lowest detection limit of 50 nM of EP was achieved at SAMF modified electrode. Simultaneous amperometric determination of AA and EP was also achieved at the SAMF modified electrode. Common physiological interferents such as uric acid, glucose, urea and NaCl do not interfere within the potential window of EP oxidation. The present 4α‐Ni^IITAPc SAMF modified electrode was also successfully applied to determine the concentration of EP in commercially available injection.     

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.     

Voltammetric Determination of Epinephrine in the Presence of Uric Acid Based on Aminated Graphene and Ag NPs Hybrid Membrane Modified Electrode

A hybrid membrane consisted of aminated graphene and Ag nanoparticles（Ag NPs） was prepared on the surface of glassy carbon electrode（GCE） by cyclic voltammetry（CV） with aminated graphene（GR-NH2） as matrix for immobilizing Ag NPs.The morphology and electrochemical properties of this hybrid membrane were characterized by scanning electron microscopy（SEM） and CV,respectively,and on this membrane,the voltammetric behaviors of epinephrine（EP） were studied in detail.The membrane exhibited excellent eletro-catalytic activities for the redox of EP,and could resolve the electrochemical response of EP and uric acid（UA） into two oxidation peaks.The peak current of EP was linear with its concentration in the ranges of 0.916-18.3 μmol/L and 18.3-184 μmol/L.The detection limit was 2.0 nmol/L（S/N=3）.The proposed modified electrode retained the advantages of easy fabrication,high sensitivity and good repeatability for the determination of EP.