聚4-(2-吡啶偶氮)间苯二酚膜修饰玻碳电极测定过氧化氢

利用循环伏安法（-0.5～2.2 V）将4-(2-吡啶偶氮)间苯二酚(PAR)电聚合修饰到玻碳电极表面,制备了聚PAR膜过氧化氢（H2O2）传感器。 并采用循环伏安法和计时安培法研究了修饰电极的电化学性质和对H2O2的响应特性。 结果表明,PAR膜修饰电极在低的电位下对H2O2具有优异的电催化还原效应。 在磷酸盐缓冲溶液中(pH=8.0)用计时安培法对H2O2进行了测定（工作电位0.45 V）,响应电流与其浓度在2×10-5～1.76×10-3 mol/L范围内呈良好的线性关系,线性相关系数r=-0.999 83,检测限(S/N=3)为3 μmol/L。该修饰电极灵敏度高、稳定性好、制备简单,在H2O2的测定中对抗坏血酸、尿酸和葡萄糖有较好的抗干扰性。     

MnO_2-GO_x碳糊电极对葡萄糖的电位响应

研制一种新型二氧化锰-酶修饰碳糊电极.应用直接电位法分别研究了磷酸盐底液的pH值、不同种类的粘合剂、二氧化锰修饰含量以及温度等各因素对该修饰电极测定H2O2和葡萄糖电位响应的影响.在优化实验条件(35℃,磷酸缓冲底液pH=7)下,葡萄糖检测的线性范围为2.0×10-5~5.2×10-3mol.L-1,灵敏度:36.12~34.62 mV/pG lucose,检测限:3.3×10-6mol.L-1.该电极具有良好的选择性、灵敏度、稳定性和重复性,大多数常见阴阳离子、甘露醇、丙三醇和脲不干扰测定.     

A high-sensitive amperometric hydrogen peroxide biosensor based on the immobilization of hemoglobin on gold colloid/L-cysteine/gold colloid/nanoparticles Pt-chitosan composite film-modified platinum disk electrode

A hemoglobin (Hb)/gold colloid (nano-Au)/L-cysteine (L-cys)/nano-Au/nanoparticles Pt (nano-Pt)-chitosan (CHIT) composite film-modified platinum disk electrode (abbreviated to modified electrode) has been prepared to construct a biosensor for determination of H(2)O(2). The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The modified process was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The morphologies of different composite film were investigated with scanning electron microscopy (SEM) and the element of composite film was investigated with X-ray photoelectron spectroscopy (XPS). Analytical parameters such as pH and temperature were also studied. The linear range for the determination of H(2)O(2) is 1.4 x 10(-7) to 6.6 x 10(-3)mol/L with a detection limit of 4.5 x 10(-8)mol/L (S/N=3). The sensor achieved 95% of the steady-state current within 10s. The sensor exhibited high sensitivity (17.62 microA/(mmol L)), selectivity and stability. The method is applied to the determination of H(2)O(2) with satisfactory results.     

Electrocatalytic Oxidation and Ion Chromatography Detection of S2O32-, SO32-, I- and SCN- at Glassy Carbon Electrode with Functionalized Multi-Wall Carbon Nanotubes Film

In this research, a glassy carbon electrode modified with the functionalized multi-wall carbon nanotubes (MWNT-COOHs) film was used as an amperometric sensor for the determination of S2O32-, SO23-, I- and SCN-. The electrochemical behavior of those oxidizable inorganic anions at this modified electrode was studied by means of cyclic voltammetry(CV). The experimental results indicate that the modified electrode exhibits a high electrocatalytic activity towards the oxidation of those anions with a relatively high sensitivity, a good stability and a long-life. Separated by ion chromatography(IC) with 1.25 mmol/L H2SO4 as an eluent,those oxidizable anions can be determined by the MWNT-COOHs modified electrode successfully. Under the optimal chromatographic conditions, the detection limits are 1.5 × 10-7 mol/L for S2O23-, 2. 5 × 10-7 mol/L for SO32-, 1.2 × 10-7 mol/L for I- and 2. 0 × 10-7 mol/L for SCN-, respectively. The method was applied successfully to the determination of those anions in environmental water.     

纳米Fe_2O_3修饰涂碳型硫酸沙丁胺醇选择电极的研制与应用

制备了以纳米Fe_2O_3为修饰剂的涂碳型硫酸沙丁胺醇选择电极,采用电位分析方法对其各项性能进行测定。结果表明,该纳米Fe_2O_3修饰电极有很好的能斯特响应,其线性范围为1.0×10~(-6)~0.1 mol/L,级差电位为59 mV/pC,与普通电极相比,响应时间较短(10 s),检出限更低(2.8×10~(-7)mol/L)。将修饰电极应用于猪肉样品中硫酸沙丁胺醇含量的测定,结果与标准方法结果相符。     

Simultaneous determination of sugars and ascorbic acid by capillary zone electrophoresis with amperometric detection at a carbon paste electrode modified with polyethylene glycol and Cu(2)O

In this paper, a kind of novel carbon paste electrode modified with double modifiers-polyethylene glycol (PEG) and Cu(2)O (PEG/Cu(2)O CPME) in capillary zone electrophoresis with amperometric detection (CZE-AD) was applied to simultaneously determine three sugars: glucose, sucrose, fructose and ascorbic acid (AA). The catalytic electrochemical properties of PEG/Cu(2)O CPME could enhance sensitivity obviously compared with carbon paste electrode modified with only PEG or Cu(2)O at a relatively lower detection potential (+0.3 V versus SCE). Especially, the electrochemical detection response of AA increased obviously to the same level of saccharides by adding PEG into the Cu(2)O carbon paste modified electrode. The four analytes could be perfectly separated within 22 min, the linear ranges were from 1.0 x 10 (-6) to 5.0 x 10(-5) mol L(-1) and the detection limits were at 10(-7) mol L(-1) magnitude (S/N=3). The present working electrode was successfully employed to analyse beverage samples with recoveries in the range 93-107% and RSDs less than 4%. Above results demonstrated that capillary zone electrophoresis coupled with the PEG/Cu(2)O carbon paste modified electrode was of convenient preparation, high sensitivity, good repeatability and could be used in the rapid determination of practical samples.     

基于新型二氧化锰-碳纳米管复合材料的高灵敏过氧化氢传感器

本文以多壁碳纳米管(MWCNTs)和KMnO4为原料,通过直接氧化还原反应合成了一种新型MnO2-C纳米复合材料,将其滴涂在玻碳(GC)电极表面,成功制备出一种非酶型H2O2传感器。采用循环伏安法和计时电流法研究了该传感器对H2O2的电催化氧化行为。实验结果表明,与GC电极和MWCNTs修饰电极相比,该电极对H2O2氧化显示出更好的催化活性。实验对影响电极性能的各种参数,包括pH值、工作电位及MnO2-C修饰量进行了探讨。在最佳实验条件下,传感器对H2O2响应的线性范围为5.0×10-7～0.2mol·L-1,检测限(S/N=3)为1.4×10-7 mol·L-1。该传感器选材新颖,制备方法简单,重现性好,稳定性和抗干扰能力强。     

壳聚糖-铜复合物修饰电极对过氧化氢电催化性能的研究

将壳聚糖与铜盐通过配位结合制得壳聚糖-铜复合物(CTS-Cu),并用其修饰玻碳电极,使用循环伏安法和计时安培法研究了该修饰电极对H2O2的电催化性能,对其催化机理进行了探讨.优化的实验条件为:以0.1 mol/L.磷酸缓冲溶液(PBS,pH 7.0)为反应介质,CTS-Cu修饰液中的铜离子浓度为6 mmol/L,工作电...     

Determination of the active ingredients in Gastrodia rhizoma by capillary electrophoresis with electrochemical detection

A simple, reliable and reproducible method, based on capillary electrophoresis (CE) with electrochemical detection (ED), for the determination of five active ingredients and three carbohydrates in extracts of Gastrodia rhizoma is described in this work. The main active ingredients are gastrodin, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin. Operated in a wall-jet configuration, a 300 microm diameter carbon disc electrode was used as a working electrode, with a good response at +1000 mV (vs. SCE) for 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin; a 300 microm diameter copper disc electrode exhibits a good response at +650 mV (vs. SCE) for gastrodin, sucrose, glucose and fructose. Under optimum conditions, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin in 100 mmol l(-1) borate buffer (pH 9.2) and gastrodin, sucrose, glucose and fructose in 50 mmol l(-1) sodium hydroxide buffer were baseline separated within 18 min. The response was linear over two orders of magnitude with a detection limit (S/N = 3) in the range 3 x 10(-7)-1.8 x 10(-6) mol l(-1) for all eight analytes. This method was successfully used in the analysis of traditional Chinese medicine, and the assay results were satisfactory.     

Synthesis, characterization, and electrochemiluminescence of luminol-reduced gold nanoparticles and their application in a hydrogen peroxide sensor

It was found that chloroauric acid (HAuCl(4)) could be directly reduced by the luminescent reagent luminol in aqueous solution to form gold nanoparticles (AuNPs), the size of which depended on the amount of luminol. The morphology and surface state of as-prepared AuNPs were characterized by transmission electron microscopy, UV/visible spectroscopy, X-ray photoelectron spectroscopy, FTIR spectroscopy, and thermogravimetric analysis. All results indicated that residual luminol and its oxidation product 3-aminophthalate coexisted on the surface of AuNPs through the weak covalent interaction between gold and nitrogen atoms in their amino groups. Subsequently, a luminol-capped AuNP-modified electrode was fabricated by the immobilization of AuNPs on a gold electrode by virtue of cysteine molecules and then immersion in a luminol solution. The modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The as-prepared modified electrode exhibited an electrochemiluminescence (ECL) response in alkaline aqueous solution under a double-step potential. H2O2 was found to enhance the ECL. On this basis, an ECL sensor for the detection of H2O2 was developed. The method is simple, fast, and reagent free. It is applicable to the determination of H2O2 in the range of 3x10(-7)-1x10(-3) mol L(-1) with a detection limit of 1x10(-7) mol L(-1) (S/N=3).     

Covalent modification of glassy carbon electrode with aspartic acid for simultaneous determination of hydroquinone and catechol

Glassy carbon electrode (GCE) is covalently modified with aspartic acid (Asp). The modified electrode is used for the simultaneous electrochemical determination of hydroquinone (HQ) and catechol (CC) and shows an excellent electrocatalytical effect on the oxidation of HQ and CC by cyclic voltammetry (CV) in 0.1 mol/L acetate buffer solution (pH 4.5). In differential pulse voltammetric (DPV) measurements, the modified electrode could separate the oxidation peak potentials of HQ and CC present in binary mixtures by about 101 mV though the bare electrode gave a single broad response. A successful elimination of the fouling effect by the oxidized product of HQ on the response of CC has been achieved at the modified electrode. The determination limit of HQ in the presence of 0.1 mmol/L CC was 9.0 x 10(-7) mol/L and the determination limit of CC in the presence of 0.1 mmol/L HQ was 5.0 x 10(-7) mol/L. The proposed method has been applied to the simultaneous determination of HQ and CC in a water sample with simplicity and high selectivity.     

Evaluation of a carbon paste electrode modified with organofunctionalised SBA-15 nanostructured silica in the simultaneous determination of divalent lead, copper and mercury ions

The performance of a carbon paste electrode (CPE) modified with SBA-15 nanostructured silica organofunctionalised with 2-benzothiazolethiol in the simultaneous determination of Pb(II), Cu(II) and Hg(II) ions in natural water and sugar cane spirit (cacha?a) is described. Pb(II), Cu(II) and Hg(II) were pre-concentrated on the surface of the modified electrode by complexing with 2-benzothiazolethiol and reduced at a negative potential (-0.80 V). Then the reduced products were oxidised by DPASV procedure. The fact that three stripping peaks appeared on the voltammograms at the potentials of -0.48 V (Pb2+), -0.03 V (Cu2+) and +0.36 V (Hg2+) in relation to the SCE, demonstrates the possibility of simultaneous determination of Pb2+, Cu2+ and Hg2+. The best results were obtained under the following optimised conditions: 100 mV pulse amplitude, 3 min accumulation time, 25 mV s(-1) scan rate in phosphate solution pH 3.0. Using such parameters, calibration graphs were linear in the concentration ranges of 3.00-70.0 x 10(-7) mol L(-1) (Pb2+), 8.00-100.0 x 10(-7) mol L(-1) (Cu2+) and 2.00-10.0 x 10(-6) mol L(-1) (Hg2+). Detection limits of 4.0 x 10(-8) mol L(-1) (Pb2+), 2.0 x 10(-7) mol L(-1) (Cu2+) and 4.0 x 10(-7) mol L(-1) (Hg2+) were obtained at the signal noise ratio (SNR) of 3. The results indicate that this electrode is sensitive and effective for simultaneous determination of Pb2+, Cu2+ and Hg2+ in the analysed samples.     

Differential pulse anodic stripping voltammetric determination of traces of copper with a tobramycin-Nafion modified electrode.

A Nafion-modified glassy carbon electrode incorporated with tobramycin for the voltammetric stripping determination of Cu2+ has been explored. The electrode was fabricated by tobramycin containing Nafion on the glassy carbon electrode surface. The modified electrode exhibited a significantly increased sensitivity and selectivity for Cu2+ compared with a bare glassy carbon electrode and the Nafion modified electrode. Cu2+ was accumulated in HAc-NaAc buffer (pH 4.6) at a potential of -0.6 V (vs. SCE) for 300 s and then determined by differential pulse anodic stripping voltammetry. The effects of various parameters, such as the mass of Nafion, the concentration of tobramycin, the pH of the medium, the accumulation potential, the accumulation time and the scan rate, were investigated. Under the optimum conditions, a linear calibration graph was obtained in the concentration range of 1.0 x 10(-9) to 5.0 x 10(-7) mol l(-1) with a correlation coefficient of 0.9971. The relative standard deviations for eight successive determinations were 4.3 and 2.9% for 1.0 x 10(-8) and 2.0 x 10(-7) mol l(-1) Cu2+, respectively. The detection limit (three times signal to noise) was 5.0 x 10(-10) mol l(-1). A study of interfering substances was also performed, and the method was applied to the direct determination of copper in water samples, and also in analytical reagent-grade salts with satisfactory results.     

An amperometric hydrogen peroxide biosensor based on immobilizing horseradish peroxidase to a nano-Au monolayer supported by sol-gel derived carbon ceramic electrode

A novel strategy for fabricating horseradish peroxidase (HRP)-based H(2)O(2) sensor has been developed by combining the merits of carbon sol-gel supporting matrix and nano-scaled particulate gold (nano-Au) mediator. The thiol functional group-derived carbon ceramic electrode (CCE) was first constructed using (3-mercaptopropyl) trimethoxy silane as sol-gel monomer. Then, the stable nano-Au monolayer was obtained through covalent linkage between nano-Au and thiol group on the surface of CCE. The experimental results showed that nano-Au monolayer formed not only could steadily immobilize HRP but also efficiently retain its bioactivity. Hydrogen peroxide was detected with the aid of hydroquinone mediator to transfer electrons between the electrode and HRP. The process parameters for the fabrication of the enzyme electrode and various experimental variables such as the operating potential, mediator concentration and pH of background electrolyte were explored for optimum analytical performance of the enzyme electrode. The biosensor had a fast response of less than 8 s with linear range of 1.22 x 10(-5) to 1.10 x 10(-3)mol l(-1) and a detection limit of 6.1 x 10(-6)mol l(-1). The sensitivity of the sensor for H(2)O(2) was 0.29 A l mol(-1) cm(-2). The activation energy for enzyme reaction was calculated to be 10.1 kJ mol(-1). The enzyme electrode retained 75% of its initial activity after 5 weeks storage in phosphate buffer at pH 7.     

A Tubulin‐Based Quantitative Assay for Taxol (Paclitaxel) with Enzyme Channeling Sensing

We report the development and characterization of a biosensor for sensitive and rapid determination of the anticancer agent Taxol (paclitaxel). The sensor is based on the interaction of Taxol with its receptor protein tubulin in conjunction with the separation‐free immunosensor technique of enzyme channeling. The sensor system consisted of a three electrode electrochemical cell containing a graphite carbon electrode modified with glucose oxidase and tubulin as working electrode poised at +40 mV (vs. Ag/AgCl). Addition of Taxol, horseradish peroxidase labeled Taxol, glucose and potassium iodide to the cell generated a cathodic current response that was proportional to the concentration of Taxol in the range of 10 to 1 000 pM.     

Electrochemical determination of dopamine using a poly(2-picolinic acid) modified glassy carbon electrode

A poly(2-picolinic acid) chemically modified electrode (CME) for the determination of dopamine (DA) by cyclic voltammetry is described. Compared with a bare glassy carbon electrode, the CME exhibits a 200 mV shift of the oxidation potential of DA in the cathodic direction and a marked enhancement of the current response. In pH 7.0 buffer solution, a linear calibration graph is obtained over the range from 2.5 x 10(-7) to 1.0 x 10(-5) mol dm-3 with a correlation coefficient of 0.998. The detection limit is 3.0 x 10(-8) mol dm-3. The modified electrode eliminated efficiently the interference from ascorbic acid (AA) when present in a 150-fold concentration ratio. It also showed excellent stability and reproducibility.     

Diffusion coefficient measurements in microfluidic devices

A glassy carbon electrode (GCE) modified with Pd/IrO(2) provides excellent electrocatalytic oxidation of hydrogen peroxide. Glucose oxidase (GOD) and xanthine oxidase (XOD) were co-immobilized on the modified electrode with a thin film Nafion coated on the enzyme layer to form a glucose (Glu)/hypoxanthine (Hx) sensor, without interference from electroactive species such as ascorbic acid (AA) and uric acid (UA). Its response was evaluated with respect to the enzyme amount on the electrode, pH and temperature of the electrolyte. The prepared bienzymic biosensor, used as the detector of HPLC gave a detection limit of 1.0x10(-6) mol l(-1) Glu and 2.0x10(-7) mol l(-1) Hx (Hx) with a linear concentration range of 5.0x10(-6)-2.5x10(-3) mol l(-1) and 1.0x10(-6)-5.0x10(-4) mol l(-1), respectively. Coupled with microdialysis, it was used to monitor the concentrations of Glu and Hx in rat brain.     

Association interaction and voltammetric determination of 1-aminopyrene and 1-hydroxypyrene at cyclodextrin and DNA based electrochemical sensors

The aim of this work was voltammetric determination of 1-aminopyrene and 1-hydroxypyrene using carbon paste electrodes modified with cyclodextrin derivatives and double stranded deoxyribonucleic acid (dsDNA). The detection schemes based on a preconcentration and differential pulse voltammetric (DPV) determination at beta-cyclodextrin and gamma-cyclodextrin modified carbon paste electrode (beta-CD/CPE, gamma-CD/CPE), neutral beta-cyclodextrin polymer and carboxymethyl-beta-cyclodextrin polymer modified screen-printed electrode (beta-CDP/SPE, beta-CDPA/SPE) and dsDNA modified screen-printed electrode (DNA/SPE) are proposed for the trace determination of studied analytes within the concentration range from 2 x 10(-8) to 4 x 10(-7) mol dm(-3) and from 2 x 10(-7) to 4 x 10(-6) mol dm(-3) with the limits of quantification down to 10(-8) mol dm(-3). Depending on pH, 1-aminopyrene interacts with both surface attached CD and DNA by electrostatic bonds and supramolecular complexation while 1-hydroxypyrene associates with the CD hosts via complexation. The 1-aminopyrene interaction with dsDNA was confirmed by fluorimetric measurements in the solution phase using a competing DNA-TO-PRO-3 dye complex. In addition, the effect of temperature on this association was investigated using an electrically heated DNA-modified carbon paste electrode (DNA/CPE).     

Fiberoptic biosensors based on chemiluminescent reactions

The chemiluminescence of luminol in the presence of H₂O₂ has been exploited to develop fiberoptic biosensors associated with flow injection analysis systems. A chlorophenol sensor was developed based on the ability of certain halophenols to enhance the peroxidase-catalyzed luminol chemiluminescence. Horseradish peroxidase immobilized on a collagen membrane was used. Ten chlorophenols have been tested with this chemiluminescent-based sensor. The lower detection limit was obtained with 4-chloro-3-methylphenol and was equal to 0.01 μM. Electrochemiluminescent-based fiberoptic biosensors for glucose and lactate were also developed using glucose oxidase or lactate oxidase immobilized on polyamide membranes. In the presence of oxidase-generated H₂O₂, the light emission was triggered electrochemically by means of a glassy carbon electrode polarized at +425 mV vs a platinum pseudo-reference electrode. The detection limits for glucose and lactate were 150 and 60 pmol, respectively, and the dynamic ranges were linear from 150 pmol to 600 nmol and from 60 pmol to 60 nmol, respectively.     

Zn掺杂CuO修饰电极的制备及电化学催化检测H_2O_2

利用滴涂法将Zn掺杂CuO纳米颗粒修饰到玻碳电极表面,通过循环伏安法和计时电流法,研究了Zn掺杂CuO纳米颗粒对H_2O_2的电催化性质。结果表明,制备了粒径为80~100nm的纳米颗粒,且分散良好。Zn掺杂CuO纳米颗粒修饰电极对H_2O_2具有良好的电催化还原作用。在pH=7.0的磷酸盐缓冲液中,当扫描速度介于20~350mV/s时,其氧化峰和还原峰电流均与扫描速度呈线性关系,说明电化学过程受吸附控制。探讨了支持电解质及pH值的影响,当H_2O_2的浓度在1.0×10~(-6)~6.3×10~(-3) mol/L浓度范围内时,还原峰电流与浓度呈良好的线性关系,检出限为0.1μmol/L。该传感器具有选择性高、重现性和稳定性好等特点。