聚多巴胺/多壁碳纳米管/玻璃碳电极上多巴胺的电分析

基于多巴胺（DA）在多壁碳纳米管（MWCNTs）修饰玻璃碳（GC）电极上的电聚合,制得聚多巴胺(PDA)/MWCNTs/GC电极,并对该修饰电极进行了电化学阻抗谱 (EIS)和循环伏安法(CV)表征。 在该修饰电极上,DA呈现良好的电化学行为。在pH=7.4磷酸缓冲溶液中其氧化电流显著高于在裸电极上的响应,且能有效地抑制2.0 mmol/L抗坏血酸(AA)或K4Fe(CN)6的直接电化学响应,表明MWCNTs可增敏信号,且阳离子选择透过性PDA膜可抑制阴离子的电化学干扰。 采用CV实验检测DA,DA氧化的半微分伏安峰高(ipa-sd)与多巴胺浓度在0.08～1.76 μmol/L范围内呈线性关系,在无抗坏血酸和有0.5 mmol/L抗坏血酸共存时的线性回归方程分别为ipa-sd(μA/s1/2)=0.107+0.405c(μmol/L)（r2=0.986）和ipa-sd(μA/s1/2)=0.628+0.649c(μmol/L)(r2=0.992),检测限均为8.0×10-8 mol/L(S/N=3)。 该法用于盐酸多巴胺注射液中多巴胺的快速测定,结果满意。     

抗坏血酸在离子液体修饰玻碳电极上的电化学行为

利用离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)对玻碳电极(GCE)进行修饰,制备了BMI-MBF4/GCE电极.在0.1mol/L的磷酸盐缓冲溶液中,采用循环伏安法研究了抗坏血酸在BMIMBF4/GCE电极和裸玻碳电极(GCE)上的电化学行为.结果表明,pH=5.7的磷酸盐缓冲溶液为最佳测定底液,最佳富集时间为120s;BMIMBF4/GCE对抗坏血酸的氧化反应有很好的电化学催化作用.抗坏血酸的氧化峰电流与其浓度在2.0×10-4～1.0×10-2 mol/L的范围内呈良好的线性关系,相对标准偏差为4.53%(n=5).     

聚中性红/纳米二氧化硅复合修饰电极直接测定抗坏血酸

用滴涂法和电化学聚合法制备了聚中性红/纳米二氧化硅修饰电极(PNR/nano-SiO2/GCE),并用循环伏安法和交流阻抗法研究了修饰电极表面的电化学行为。实验表明,该修饰电极对抗坏血酸(AA)表现出良好的电催化氧化性能,探讨了复合修饰电极协同增效作用的机理。用线性扫描伏安法研究了AA浓度与峰电流之间线性关系,在pH2.0的磷酸盐缓冲溶液中,AA氧化峰电流在1.8×10-6～5.0×10-3mol/L浓度范围内呈良好的线性关系,检出限为5.4×10-7mol/L(S/N=3)。该修饰电极制备简单,可用于药品及果蔬食品中抗坏血酸的直接测定。     

单分子层γ-氨基丁酸共价修饰玻碳电极同时测定多巴胺、尿酸和抗坏血酸

采用电氧化法制备了一种新型γ-氨基丁酸(ABA)修饰的玻碳电极.X射线光电子能谱(XPS)和循环伏安法研究表明,ABA以单分子层状态以C—N键牢固地共价键合在电极表面.该修饰电极对多巴胺(DA)、尿酸(UA)和抗坏血酸(AA)都具有良好的电化学催化特性.在pH=7.0磷酸缓冲溶液中,DA,UA和AA分别于0.45,0.25和0.07V(vs.Ag/AgCl)有一个良好的、独立的阳极方波伏安峰,表明此修饰电极可用于这3种物质的同时测定.与DA,UA和AA的方波伏安峰电流呈线性关系的浓度范围分别为4.0～400,2.0～500和1.0～600μmol/L,检测限(3δ)分别为1.6,1.2和0.8μmol/L.该修饰电极具有良好的灵敏度、选择性和稳定性,并具有抗污染能力.     

抗坏血酸在β-环糊精/二茂铁甲酸修饰电极上的电化学行为及测定

利用主客体化学反应将二茂铁甲酸包络在β-环糊精聚合物的空穴中,用新鲜蛋清作交联剂制成β-环糊精聚合物/二茂铁甲酸化学修饰玻碳电极,用电化学阻抗法和循环伏安法研究了修饰电极的电化学性能。在pH 7.0的磷酸盐缓冲溶液中,该修饰电极对抗坏血酸的电化学氧化有很好的催化活性,氧化峰电流与其浓度在6.2×10-6~5.0×10-3mol/L范围内呈良好的线性关系,线性回归方程为ip=0.4375+0.0301C(ip:μA,C:μmol/L),相关系数r=0.9982,检出限为1.0×10-6mol/L。抗坏血酸和多巴胺在修饰电极上于不同的电位(ΔE=490 mV)被氧化,可用于多巴胺存在下选择性测定抗坏血酸。     

聚缬氨酸修饰电极在抗坏血酸共存下选择性测定去甲肾上腺素

利用循环伏安法制备了聚缬氨酸修饰电极,在缬氨酸浓度为0.01 mol/L的磷酸盐缓冲溶液(pH=9.0)中,起止电位范围为1.0～2.4 V,以40 mV/s扫描速率循环扫描9周进行聚合. 聚缬氨酸膜对去甲肾上腺素(NE)的电化学氧化具有明显的催化作用. 研究了NE在聚缬氨酸修饰电极上的电化学行为,建立了测定NE的电化学分析新方法. pH值在2.2～8.0范围内,研究了磷酸盐缓冲溶液pH值对NE电化学行为的影响. 结果表明,氧化还原峰电位随pH值升高发生负移;在pH=4.0磷酸盐缓冲溶液中,NE在修饰电极上呈现1对灵敏的氧化还原峰,利用循环伏安法测定NE还原峰电流可排除抗坏血酸(AA)干扰. NE在聚缬氨酸修饰电极上的还原峰电流与其浓度在4.6×10-7～1.1×10-5 mol/L和1.1×10-5～1.2×10-4 mol/L范围内呈良好线性关系;相关系数分别为0.995 7和0.991 8;检出限(S/N=3)为8.0×10-8 mol/L;其回归方程为ipc(A)=6.80×10-7+1.05c,ipc(A)=1.23×10-5+0.16c. 修饰电极具有良好的灵敏度、选择性和稳定性,可用于去甲肾上腺素针剂样品分析.     

抗坏血酸辅助碳纤维超微电极特异性检测特布他林

采用循环伏安法(CV)、差分脉冲伏安法(DPV)研究了特布他林与抗坏血酸共存的条件下在碳纤维超微电极上的电化学行为.通过优化抗坏血酸浓度,建立了一种电化学定量检测特布他林的方法.实验结果表明,在20 mmol/L pH 7.0的Tris-HCl缓冲溶液中,当共存的抗坏血酸浓度为1×10~(-4) mol/L时,对碳纤维电极检测特布他林具有较好的稳定作用.在优化条件下,采用DPV法对特布他林进行定量分析,特布他林的氧化峰电流与其浓度在1×10~(-6)～1×10~(-4) mol/L范围内呈良好的线性关系,线性相关系数为R~2=0.994 2,检测限达2.202×10~(-10) mol/L (S/N=3).该修饰方法重现性好,电极稳定性佳,可应用于生物样品中特布他林的高灵敏分析.     

聚赖氨酸修饰电极在抗坏血酸共存时测定肾上腺素

在pH8.0磷酸盐缓冲溶液(PBS)中利用循环伏安法制备了聚赖氨酸修饰电极,在pH4.0 PBS中,聚赖氨酸膜对肾上腺素(EP)的电化学氧化具有明显的催化作用.利用循环伏安法测定EP还原峰电流可排除抗坏血酸(AA)干扰.肾上腺素还原峰电流与其浓度分别在6.3×10-7mol/L~1.0×10-5 mol/L与1.0×10-5mol/L~1.2×10-4 mol/L范围内呈良好线性关系,相关系数分别为0.9978与0.9975,;检出限(S/N=3)为7.2×10-8mol/L.该方法具有良好的灵敏度、选择性,已用于针剂样品分析.     

芦丁在纳米金修饰玻碳电极上的电化学行为及其测定

采用循环伏安法将纳米金电沉积于玻碳电极表面,制备了纳米金修饰玻碳电极(NG/GCE).在pH3.29的Britton-Robinson(B-R)缓冲溶液中,用循环伏安法研究了芦丁在NG/GCE上的电化学行为.结果表明,NG/GCE对芦丁的氧化还原反应有良好的电催化作用.用方波伏安法测得芦丁的还原峰电流与其浓度在2.0×10-8～2.0×10-6mol/L范围内呈线性关系,检出限为1.0×10-8mol/L(S/N=3).     

聚对苯二酚修饰玻碳电极的制备及其对抗坏血酸的催化氧化作用

采用循环伏安(CV)法制备了聚对苯二酚薄膜修饰玻碳电极,利用其电催化氧化作用建立了抗坏血酸的定量分析方法,探讨了其催化氧化机理。研究发现:在0.2 mol/L Na2HPO4-NaH2PO4(PBS,pH 7.0)缓冲溶液中,以0.1 mol/L KC l作支持电解质,聚对苯二酚修饰电极(PHQ/CME)对抗坏血酸(AA)存在灵敏的催化氧化作用,氧化峰电位负移177 mV。应用微分脉冲伏安法(DPV)对AA进行定量分析,其氧化峰电流与AA浓度在3.3×10-5~1.7×10-2mol/L和1.7×10-2~1.2×10-1mol/L范围内呈良好的线性关系,检出限为3.3×10-6mol/L。机理研究结果表明:PHQ/CME上带有的酚羟基与脱氢抗坏血酸自由基之间形成的氢键是电催化氧化的主要原因。     

Congo Red Immobilized on a Silica/Aniline Xerogel: Preparation and Application as an Amperometric Sensor for Ascorbic Acid

Congo red (CR) was immobilized on a silica/aniline xerogel through electrostatic interaction. The dye is strongly retained and is not easily leached from the xerogel matrix. The material containing the adsorbed dye was used to prepare a carbon paste electrode and the electrochemical properties of the hybrid material were investigated using cyclic voltammetry and amperometry. The modified electrode was used to study the electrochemical oxidation of ascorbic acid. The adsorbed dye mediates ascorbic acid oxidation at the solid electrode surface‐solution interface at an anodic potential of 0.18 V at pH 7, in a 0.5 mol L^?1 KCl solution. This novel modified carbon paste electrode shows good analytical performance for the determination of ascorbic acid in commercial Vitamin C tablets.     

Amperometric determination of ascorbic acid at a novel ‘self-doped’ polyaniline modified microelectrode

A ‘self-doped’ polyaniline modified microelectrode, prepared by cyclic potential sweep on a microdisk gold electrode from –0.2 to 0.85 V in 0.5 mol/L sulfuric acid containing aniline and o-aminobenzoic acid, has been developed. The copolymerized process and the resulting polymer characteristics were investigated in detail. This composite film indicated a good electrochemical activity in a wide pH range even in basic solution. Meanwhile, the redox couple exhibited an excellent electrocatalytic activity for the oxidation of ascorbic acid. The oxidation overpotential of ascorbic acid was decreased over 200 mV at this modified electrode compared with a bare gold one. Moreover, the effects of film thickness and pH on the catalytic efficiency were further studied. The dependence of catalytic currents on the concentration of ascorbic acid was linear in the range of 1.2 × 10^–5～ 2.4 × 10^–3 mol/L with a correlation coefficient of 0.996. Also, the determination of ascorbic acid in actual samples was evaluated and the results are satisfactory.     

聚色氨酸／镍复合膜修饰电极测定抗坏血酸的研究

采用电化学聚合法制备了聚色氨酸／镍复合膜修饰玻碳电极,研究了抗坏血酸在该修饰电极上的电化学行为,建立了测定痕量抗坏血酸的新方法。在pH6．2的磷酸盐缓冲溶液中,抗坏血酸在修饰电极上产生一个灵敏的氧化峰,采用线性扫描伏安法测定,其氧化峰电流与抗坏血酸浓度在2．0×10^-6 -1．0×10^-3mol／L范围内呈良好的线性关系,检出限为5．0×10^-7mol／L。对1．0×10^-4mol／L抗坏血酸溶液平行测定6次,测定结果的相对标准偏差为1．9％。该法用于片剂中抗坏血酸含量的测定,加标回收率为97．8％～101．2％。     

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。     

Amperometric determination of ascorbic acid at a novel ‘self-doped’ polyaniline modified microelectrode

A ‘self-doped’ polyaniline modified microelectrode, prepared by cyclic potential sweep on a microdisk gold electrode from –0.2 to 0.85 V in 0.5 mol/L sulfuric acid containing aniline and o-aminobenzoic acid, has been developed. The copolymerized process and the resulting polymer characteristics were investigated in detail. This composite film indicated a good electrochemical activity in a wide pH range even in basic solution. Meanwhile, the redox couple exhibited an excellent electrocatalytic activity for the oxidation of ascorbic acid. The oxidation overpotential of ascorbic acid was decreased over 200 mV at this modified electrode compared with a bare gold one. Moreover, the effects of film thickness and pH on the catalytic efficiency were further studied. The dependence of catalytic currents on the concentration of ascorbic acid was linear in the range of 1.2 × 10^–5∼ 2.4 × 10^–3 mol/L with a correlation coefficient of 0.996. Also, the determination of ascorbic acid in actual samples was evaluated and the results are satisfactory. Received: 7 October 1997 / Revised: 3 February 1998 / Accepted: 7 February 1998     

苯胺在邻-氨基苯磺酸功能化的玻碳电极上聚合及其对抗坏血酸的电催化氧化

通过电氧化法将ABS分子以CN键共价键合在玻碳电极(GCE)表面,形成ABS分子单层膜修饰的GCE(ABS/GCE),在此电极上对AN进行电聚合,从而制备了聚苯胺/邻氨基苯磺酸复合膜修饰电极(PAN-ABS/GCE/CME).由于ABS中磺酸基功能团对PAN的掺杂作用使PAN在中性或碱性介质中都能呈现出较好的电化学活性.研究表明,PAN-ABS/GCE/CME在PBS(pH 6.8)中对AA的电氧化具有催化作用,其氧化峰电位为0.17 V,比在裸GCE上(0.39 V)负移了0.22 V,峰电流明显升高.AA在修饰电极上的氧化峰电流与其浓度在0.5～16.5 mmol/L范围内呈良好的线性关系,其线性回归方程为ipa(μA)=20.2+6.20CAA,r=0.9973; 检出限(3δ)为7.2 μmol/L,电极具有较好的稳定性和重现性.并采用计时电流法对AA催化氧化的扩散系数和催化速率常数进行了研究.     

纳米金–壳聚糖修饰电极循环伏安法测定抗坏血酸

介绍纳米金–壳聚糖修饰电极的制备方法及其测定抗坏血酸的分析应用。采用电沉积方法,将氯金酸与壳聚糖的混合电解液直接共沉积,制备了壳聚糖–纳米金修饰玻碳电极的电化学传感器。利用循环伏安法研究了抗坏血酸浓度、p H值等对抗坏血酸在修饰电极上的电化学行为的影响。实验结果表明,修饰电极对抗坏血酸具有良好的电催化氧化作用,抗坏血酸浓度在5×10~(–5)~1×10~(–3) mol/L范围内线性良好,回归方程为I_p=0.433 8c+0.881 9,相关系数为0.998 71。该法可指导纳米金–壳聚糖修饰电极的制备及抗坏血酸含量的测定。     

Preparation of aminylferrocene/nanogold modified glassy carbon electrode and its electrocatalysis on dopamine

Aminylferrocene(FcAI)-Nanogold(NG) modified glassy carbon electrode (FcAI/NG/GCE) was prepared by the Au-N bond between Au and FcAI. Electrochemical impedance spectroscopy (EIS) was employed to study the surface of the modified electrode. The electrochemical behavior of dopamine (DA) on the modified electrode was investigated and it was found that the modified electrode had an obvious electrocatalytic effect on DA. Compared with a bare GCE, the modified electrode exhibited an apparent shift of the oxidation peak potential in the negative potential direction and a marked enhancement in the current response for DA. We investigated the determination of DA on the modified electrode by differential pulse voltammetry (DPV). Linear calibration curve was obtained in the range of 7.0 x 10(-7) mol/L to 6x10(-4) mol/L of DA in 0.1 mol/L phosphate buffer solution (pH = 7.0) with a correlation coefficient of 0.9989. The detection limit (S/N = 3) of DA was estimated to be 1.0 x 10(-7) mol/L. Especially, by using the modified electrode, we can separate the oxidation peaks of ascorbic acid (AA) and DA in the PBS and it was satisfactory for the determination of DA with the interference of AA.     

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.