氮掺杂碳纳米管修饰电极的电化学行为

制备了氮掺杂改性的碳纳米管, 并用循环伏安法(CV)测定了多巴胺(DA)和抗坏血酸(AA)在不同氮含量的碳纳米管修饰电极上的电化学行为. 结果表明, 氮掺杂碳纳米管修饰电极对AA和DA有不同的电催化行为, 其中高氮含量修饰电极对AA的催化作用强, 而低氮含量修饰电极对DA的催化作用强. 微分脉冲伏安法(DPV)的结果显示, DA的氧化峰电流与其浓度在5.0×10^－6～2.0×10^－4 mol/L范围内呈良好的线性关系, 检出限达1.64×10^－6 mol/L (S/N＝3); AA氧化峰电流与其浓度在3.0×10^－5～1.0×10^－2 mol/L范围内呈良好的线性关系, 检出限达3.26×10^－6 mol/L (S/N＝3). 该修饰电极在AA大量存在(AA浓度为DA浓度两万倍)时可选择性地实现多巴胺的测定而不造成干扰.     

聚茜素红膜修饰电极控制电位扫描法分别测定多巴胺和抗坏血酸

研究了聚茜素红膜修饰电极(PARE)的制备及其对多巴胺(DA)和抗坏血酸(AA)的电催化性能,结果表明,在PARE上DA和AA具有不同的循环伏安行为,前者表现为一个准可逆过程,后者则为不可逆过程,并且二者的氧化峰电位分开近200mV.因此可通过控制不同的电位范围进行分步扫描,实现了对同一体系中DA和AA的分别测定,DA的还原峰电流和AA的氧化峰电流分别在8.0×10^-6～4.0×10^-3mol/L和4.0×10^-5～2.0×10^-2mol/L范围内与各自的浓度呈线性关系;检测限分别为8.0×10^-7mol/L和1.0×10^-5mol/L.同时与导数伏安法一步测定进行比较,结果令人满意.     

用季铵盐定域体制备高碘酸根离子电极的研究

实验比较了若干种长链季铵盐制备高碘酸根离子电极,以十六烷基三辛基高碘酸季铵盐(HTOA-IO₄)制备的PVC膜电极性能较佳,能斯特响应区间为1.0×10^-1-6.3×10^-8M,检测下限1.0×10^-8M,工作pH范围2.5-7.5,高碘酸在溶液中存在复杂平衡,依据pH-电位曲线,认为电极响应的Ⅰ(ⅥI)离子的主要形态为IO₄^-,据此用电位法测试了H₅IO₆的酸离解常数:K₁=5.70×10^-4,K₂=1.97×10^-7,与文献值相符,测试了不同离子的电位选择性系数。     

纳米银/聚多巴胺修饰玻碳电极的制备及电化学行为

利用电聚合法和脉冲沉积技术制备了纳米银/聚多巴胺修饰的玻碳电极. 通过循环伏安法和示差脉冲伏安法研究了该修饰电极上对硝基苯酚的电化学行为; 讨论了扫描速度和支持电解质等条件对对硝基苯酚在修饰电极上催化还原的影响. 结果表明, 对硝基苯酚的示差脉冲峰电流在4×10^-5～3×10^-4 mol/L范围内呈良好的线性关系.     

木犀草素在离子液体修饰电极上的电催化氧化及其测定

用1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)疏水性离子液体修饰玻碳电极,在0.2 mol/L磷酸盐缓冲溶液(pH为4.0～8.0)中,运用循环伏安法（CV）和差示脉冲溶出伏安法(DPSV)研究了木犀草素在修饰电极上的电化学行为,建立了测定木犀草素含量的新方法。 实验结果表明,该修饰电极上木犀草素氧化、还原峰电位均负移,峰电流增大。 在-0.2～0.7 V电位区间,pH=7.0的磷酸盐缓冲溶液体系中,木犀草素在修饰电极表面发生的是受吸附控制的准可逆等电子等质子电极反应,电子转移系数α=0.5,吸附量为4.6×10-10 mol/cm²;木犀草素氧化峰电流与其浓度在1.0×10^-10～1.6×10^-8 mol/L范围内呈良好的线性关系,检出限达到3.2×10^-11 mol/L,回收率为98.7%～102.0%;该法操作简单、快速、灵敏、准确;可用于野菊花中类黄酮的测定。     

吲哚乙酸在纳米金/碳纳米管/壳聚糖修饰玻碳电极上的电化学行为及其检测

以壳聚糖(CS)为多壁碳纳米管(MWNTs)的分散介质, 通过MWNTs/CS膜上大量氨基静电吸附纳米金粒子(nanoAu), 使玻碳电极(GCE)表面形成稳定的nanoAu-MWNTs-CS-GCE修饰层, 并采用电化学方法初步研究了该修饰电极的性能. 探讨了吲哚乙酸(IAA)在该修饰电极上的电化学行为, 结果表明, 在5～200 μmol/L浓度范围内以及0.78 V电位条件下, 以循环伏安法(CV)测得的氧化峰电流变化值与c(IAA)呈良好的线性关系, 其回归方程为y=2.34×10^-4+0.14x, 检出限为8.33×10^-6 mol/L, 相关系数为0.9997.     

高压液相色谱磷钼杂多酸修饰电极安培检测儿茶酚胺类神经递质的研究

研究了磷钼杂多酸修饰电极对去甲肾上腺素(NE)、肾上腺素(E)和多巴胺(DA)等儿茶酚胺类神经递质的催化氧化作用,探讨了催化机理,并采用高压液相色谱电化学方法对其进行了分离检测,NE、DA和E的线性范围(mol)依次为8.0×10^-11～2.0×10^-8、8.0×10^-11～2.0×10^-8、4.0×10^-11～2.0×10^-8;检测限(mol))依次为4.0×10^-11、4.0×10^-11、2.0×10^-11.7次平行测定的相对标准偏差(％)依次为1.6、2.0和4.5.将此法用于鼠脑组织中神经递质的测定,获得满意的结果.     

聚邻氨基苯硫酚/纳米金复合膜分子印迹传感器测定2, 4-二氯苯酚

在2,4-二氯苯酚(2,4-DCP)存在下, 在金电极表面自组装邻氨基苯硫酚(oATP)并电聚合oATP/金纳米粒子, 制得2,4-DCP印迹复合膜电化学传感器.采用循环伏安法和交流阻抗技术对传感器制备过程进行了表征, 以K₃Fe(CN)₆为探针, 间接对2,4-DCP进行定量分析.结果表明, 2,4-DCP在5.0×10^-8~1.2×10^-4 mol/L 浓度范围内与K₃Fe(CN)₆示差脉冲伏安曲线的峰电流呈线性关系(R²=0.9964), 检出限为1.5×10^-8 mol/L(S/N=3).该印迹传感器可在几种氯代酚干扰下选择性测定2,4-DCP.利用该传感器对环境水样进行加标回收检测, 回收率为95.2%~109.3%.     

微分脉冲阳极溶出伏安法测定碘离子

基于I-能被氧化生成IO₃^-的特性,以铂球电极为工作电极,研究了微分脉冲阳极溶出伏安法(DPAS)测定碘离子.由于产物IO₃^-在电极上有吸附,因而在+1.3V电清洗120s.在pH=4的0.1mol/LKH₂PO₄-K₂HPO₄缓冲溶液底液中,能检测出5.00×10^-7mol/L的I-,在5.00×10^-71.50×10^-5mol/L范围内I^-的浓度与峰电流有良好的线性关系.该方法用于海带、食用碘盐中碘的测定,取得了较好的结果.     

毛细管区带电泳电化学检测法测定药物及果汁中芦丁和L-抗坏血酸

用毛细管区带电泳-电化学检测法同时测定复方芦丁片及果汁中芦丁和L-抗坏血酸的含量.研究了电极电位、电解液浓度和酸度、电泳电压及进样时间等对电泳的影响,得到了较为优化的测定条件.以直径为300μm的碳圆盘电极为检测电极,电极电位为1.0V(vs.SCE),在25mmol/L硼砂-50mmol/LNaH₂PO₄(pH8.0)运行缓冲液中,上述两组分在12min内完全分离.芦丁和L-抗坏血酸浓度分别在1.0×10^-6～2.5×10^-4和5.0×10^-6～2.5×10^-3mol/L范围内与电泳峰电流呈现良好线性关系,检测下限分别为8.0×10^-7和3.3×10^-6mol/L.9次测定含5.0×10^-5mol/L芦丁和2.5×10^-4mol/LL-抗坏血酸的试样溶液,峰高的相对标准偏差分别为2.85%和1.65%,5次测得的平均回收率分别为97.73%和99.68%.     

Selective detection of dopamine in the presence of ascorbic acid by use of glassy-carbon electrodes modified with both polyaniline film and multi-walled carbon nanotubes with incorporated β-cyclodextrin

A simple, sensitive, and reliable method based on a combination of multi-walled carbon nanotubes with incorporated β-cyclodextrin (β-CD-MWNTs) and a polyaniline (PANI) film-modified glassy-carbon (GC) electrode has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The PANI film had good anti-interference properties and long-term stability, because of the permselective and protective properties of the conducting redox polymer film. The acid-treated MWNTs with carboxylic acid functional groups promoted the electron-transfer reaction of DA and inhibited the voltammetric response of AA. Sensitive detection of DA was further improved by the preconcentration effect of formation of a supramolecular complex between β-CD and DA. The analytical response of the β-CD-MWNTs/PANI film to the electrochemical behavior of DA was, therefore, better than that of a MWNTs/PANI film, a PANI film, or a bare glassy-carbon (GC) electrode. Under the conditions chosen a linear calibration plot was obtained in the range 1.0 × 10⁻⁷–1.0 × 10⁻³ mol L⁻¹ and the detection limit was 1.2 × 10⁻⁸ mol L⁻¹. Interference from AA was effectively eliminated and the sensitivity, selectivity, stability, and reproducibility of the electrodes was excellent for determination of DA.     

Covalent modification of glassy carbon electrodes with beta-alanine for voltammetric separation of dopamine and ascorbic acid.

beta-Alanine was covalently grafted on a glassy carbon electrode (GCE) by amine cation radical formation in the electrooxidation process of the amino-containing compound. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) proved the immobilization of beta-alanine monolayer on GCE. The electrode shows strong electrocatalytic functions to dopamine (DA) and ascorbic acid (AA), reducing the overpotentials by 0.20 V and 0.23 V, respectively. Due to its different catalytic effects toward DA and AA, the modified electrode resolved the overlapping voltammetric responses of DA and AA into two well-defined voltammetric peaks by CV or differential pulse voltammetry (DPV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak current obtained from DPV was linearly related to DA and AA concentrations in the ranges of 4.0 x 10(-6)-5.0 x 10(-4) mol/L and 2.0 x 10(-5)-6.0 x 10(-3) mol/L with correlation coefficients of 0.997 and 0.995, respectively. The detection limits (3 sigma) for DA and AA were 2.4 x 10(-6) mol/L and 1.2 x 10(-5) mol/L, respectively. The electrode shows good sensitivity, selectivity and stability, and has been applied to the determination of DA and AA simultaneously in samples with satisfactory results.     

Covalent modification of glassy carbon electrodes with glycine for voltammetric separation of dopamine and ascorbic acid

Glycine was covalently grafted on to a glassy carbon electrode (GCE) by amine cation radical formation in electrooxidation of the amino-containing compound. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry proved the immobilization of glycine on the GCE. The modified electrode reduced the overpotentials of dopamine (DA) and ascorbic acid (AA) by approximately 0.15 V and 0.23 V, respectively, and resolved the overlapping voltammetric response of DA and AA into two well-defined voltammetric peaks in cyclic voltammetry (CV) or differential pulse voltammetry (DPV), unlike the unmodified GCE; this can be used for the simultaneous determination of these species in a mixture. The differential pulse peak current was linearly dependent on DA and AA concentration in the range 5 x 10(-6)-8 x 10(-4) mol L(-1) and 6 x 10(-5)-4 x 10(-3) mol L(-1), with correlation coefficients of 0.996 and 0.994, respectively. The detection limits (3delta) for DA and AA were 1.8 x 10(-6) mol L(-1) and 2.1 x 10(-5) mol L(-1), respectively. The modified electrode is very sensitive, selective and stable, and has been applied to the determination of DA and AA simultaneously in samples with satisfactory results.     

钯纳米粒子在电极表面的制备及其对氧的催化还原

纳米微粒的体积效应使其成为表面纳米工程及功能化纳米结构材料制备的理想研究对象 [1～ 3] .纳米粒子具有独特的电子、催化及光学特性[4 ] ,近年来关于纳米粒子的制备及其在材料科学领域中的应用受到研究者的极大关注 .而贵金属纳米粒子由于其在催化领域中的广泛应用而成为最重要的研究对象之一[5,6 ] .电催化氧还原是一直为化学家瞩目的研究领域[7～ 9] .研究主要目的之一是寻找合适的氧电极反应催化剂 ,并使之能够应用于燃料电池中 .其中催化氧电极材料研究得最多的是贵金属 Pt[10 ,11] .贵金属 Pd对氧催化还原的研究工作很少 .我们首次…     

用聚(L-蛋氨酸)/纳米金修饰玻碳电极同时灵敏检测多巴胺和尿酸简

A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine) (PMT)-modified glassy carbon electrode (GCE) to form a nano-Au/PMT composite-modified GCE (nano-Au/PMT/GCE). Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode. The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH = 7.00). Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0×10^-8 to 10^-6 mol/L for DA and 7.0×10^-8 to 10^-6 mol/L for UA. The detection limits were 3.7×10^-8 mol/L for DA and 4.5×10^-8 mol/L for UA at a signal-to-noise ratio of 3. According to our experimental results, nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.     

聚伊文思蓝修饰电极对多巴胺和抗坏血酸的电分离及同时测定

研究多巴胺(DA)和抗坏血酸(AA)在聚伊文思蓝(Evans Blue)修饰电极上的伏安行为,建立差示脉冲伏安测定法.在pH4.5磷酸盐缓冲液中,聚伊文思蓝修饰电极对DA和AA有显著的增敏和电分离作用.DA和AA氧化峰电流与浓度分别在1.0×10-6~3.0×10-5mol/L和5.0×10-6~1.05×10-4mol/L范围内呈良好的线性关系,检测限分别为2.5×10-7mol/L和3.0×10-7mol/L.当DA与AA共存时,由该修饰电极检测的二者氧化峰电位差达184 mV,故可同时测定DA和AA,并有效消除其它组分对DA测定的干扰,已用于实际样品中DA和AA含量的测定,结果令人满意.     

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。     

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.     

Preparation of Au Nanoparticles Decorated Polyaniline Nanotube and Its Catalytic Oxidation to Ascorbic Acid

With sulfonated electrospun polystyrene fiber as a template, uniform polyaniline(PANI) nanotubes were fabricated via polymerization of aniline followed by template removal. Au nanoparticles(Au_nano) were decorated on the PANI nanotube successfully via auto-reduction of HAuCl₄ on the PANI nanotube. The morphology of the nanotubes was characterized by means of scanning electron microscopy(SEM) and transmittance electron microscopy(TEM). By varying precursor concentration and incubation time, Au_nano-PANI with different size of Au_nano was obtained conveniently. Glassy carbon electrode modified with the Au_nano decorated PANI nanotubes (Au_nano-PANI/GCE) was prepared and used seccessfully for the catalytic oxidation of ascorbic acid(AA). The results of differential pulse voltammetry indicate that there is a good linear relationship between the peak currents and the concentrations of AA in the range of 5-3000 μmol/L, with the limit of detection of 1 μmol/L(S/N>3). There is no mutual interference between AA and dopamine. The electrode has been successfully applied in the detection of AA in vitamin C tablet sample.