聚对氨基苯磺酸修饰电极测定尿酸

利用循环伏安法制备了聚对氨基苯磺酸修饰电极, 研究了尿酸在该修饰电极上的电化学行为. 结果表明, 该电极对尿酸有较强的电催化作用, 并对抗坏血酸有较强的抗干扰能力. 在pH 5.6的乙酸盐缓冲溶液中, 用循环伏安法和差分脉冲伏安法在该电极上测定了尿酸, 其线性范围分别为1.0×10-5～2.0×10-4 mol/L和4.0×10-7～1.0×10-5 mol/L, 检出限分别为6.0×10-6 mol/L和1.0×10-7 mol/L. 已用于尿液中尿酸的测定.     

Nafion聚合物涂层碳纤维微电极微分脉冲伏安法测定咖啡因的研究

咖啡因属生物碱,是中枢神经兴奋药物之一~[1]。目前,咖啡因的常用测定方法有紫外分光光度法~[2]和高效液相色谱法~[3]等.电化学测定方法已有报道~[4～6],但尚未见到利用Nafion聚合物涂层碳纤维微电极的伏安测定方法.本文提出了一种简单易行的碳纤维微电极及其Nafion聚合物涂层的制造方法.得到了利用该电极微分脉冲伏安法测定咖啡因的最佳体系为     

苝红化合物氧化还原反应的研究

苝红化合物作为一种新型功能性染料,由于吸收光能在可见范围,且性能稳定,在光导液晶及太阳能电池等方面已得到了应用^[1].     

活化玻碳电极直接测定全血中的尿酸

用阳极极化法在碱性溶液中活化玻碳电极, 研究了尿酸(UA)在活化玻碳电极(AGCE)上的电化学行为, 并提出一种利用微分脉冲伏安技术测定全血中尿酸的电化学分析方法. 在0.1 mol/L的乙酸缓冲溶液中(pH 5.0), 以0.1 mol/L KCl作为支持电解质, 尿酸在AGCE上于0.484 V 处产生一个灵敏的氧化峰. 微分脉冲伏安法测定其氧化峰电流与 UA 的浓度在5.0×10-6～2.0×10-4 mol/L范围内呈良好的线性关系, 相关系数为0.9989, 检出限为1.0×10-6 mol/L. 该方法操作简便, 重现性较好, 能在抗坏血酸存在下同时测定UA. 用于人血中UA的测定.     

尿酸在聚L-苯丙氨酸修饰电极上的伏安测定

采用循环伏安法制备了聚L-苯丙氨酸薄膜修饰玻碳电极,研究了尿酸在该修饰电极上的电化学行为,循环伏安法测定了尿酸. 研究发现,在pH=5.6的磷酸盐缓冲溶液中,尿酸在聚L-苯丙氨酸修饰电极上于0.43 V处产生1灵敏的氧化峰;循环伏安法测定其氧化峰电流与尿酸的浓度在2.0×10-6～3.0×10-4 mol/L呈良好的线性关系,检出限为1×10-6 mol/L. 对1.0×10-5 mol/L尿酸平行测定5次,相对标准偏差为3.0%. 该聚合物修饰电极制作简单,重现性好,可用于尿液中尿酸的测定,结果令人满意.     

典型表面活性剂在玻碳电极上的电化学行为及吸附模式

随着电(分析)化学的发展,表面活性剂在电化学中的应用显得越来越重要,在金属防腐[1-2]、提高电分析测定方法的选择性[3]、电活性物质增敏检测[4-5]等方面扮演着关键角色.要搞清楚相关作用机理,就需要研究表面活性剂本身在电极表面的电化学行为,而这大都与它们在电极表面的吸附有关[6].因此,研究表面活性剂在电极表面的电化学行为及其吸附模式就显得很重要,而相关的研究报导较少.     

磷钨酸改性蒙脱土-离子液体修饰电极上百草枯的电化学行为及测定

该文制备了磷钨酸改性蒙脱土-离子液体修饰电极(PTA-MMT-[BMIM]PF6/GCE),用红外光谱对PTA-MMT和[BMIM]PF6进行了表征.通过对比改性前后电极的交流阻抗图,发现PQ在PTA-MMT-[BMIM]PF6/GCE上电荷转移的电阻最小.研究了百草枯(PQ)在该修饰电极上的循环伏安行为.结果表明,在...     

十二烷基苯磺酸钠扩散系数的电化学测定

表面活性剂水溶液体系胶束扩散系数的测定是研究表面活性剂水溶液体系性质的重要方法之一。胶束扩散系数的测定已有准弹性光散射[1]、小角X-射线散射[2]、扩散-粘度[3]、极谱法[4]、循环伏安[5]等方法报导。但有关十二烷基苯磺酸钠(sod ium dodecy benzene sulfonate,SDBS)水溶     

Electrochemical Studies on the Interactions of Dipyridophenazine Complex of Ruthenium and Herring Sperm DNA

Cyclic voltammetry (CV) and single-step chronocoulometry were used to study the interaction of [Ru(phen)2dppz]2 (phen=l,10-phenanthroline; dppz=dipyrido[3,2-a:2‘,3‘-c]phen-azine) with herring sperm DNA. The addition of DNA caused a diminution in the peak current and a positive shift in the peak potential of the complex of [Ru(phen)2dppz]2 . The 12 mV positive shift in the peak potential of [Ru(phen)2dppz]^2 indicates that [Ru(phen)2dppz]^2 binds 2.6 times more strongly to DNA than its reductive form. In addition, by using fluorimetric and UV-spectrophotometric methods and studies of denatured DNA and the effect of NaC1 solution, it was also found that the binding mode was intercalation. The decrease of peak current is proportional to the concentration of DNA, which can be applied to estimate DNA concentration.     

Nafion-离子液体-修饰碳糊电极在抗坏血酸和尿酸存在下选择性测定多巴胺

用Nafion和亲水性离子液体溴化1-辛基-3-甲基咪唑([OMIM]Br)作修饰剂制作了Nafion-离子液体-修饰碳糊电极;在0.1 mol/L磷酸盐缓冲溶液(pH 7.40)中,用循环伏安法(CV)和方波伏安法(SWV)研究了多巴胺在该修饰电极上的电化学行为,建立了抗坏血酸和尿酸存在下选择性测定多巴胺的新方法.研究表明,该修饰电极降低了多巴胺氧化、还原反应的过电位,增大了其氧化、还原反应的峰电流,而抗坏血酸和尿酸在该修饰电极上无响应;在方波伏安曲线上,多巴胺的氧化电流与其浓度在3.0×10-8～2.0×10-6 mol/L范围内呈线性关系,检出限为1.0×10-8 mol/L.该法可用于注射液和模拟生物样品中多巴胺的测定.     

Voltammetric determination of salicylic acid in pharmaceuticals formulations of acetylsalicylic acid

The electrochemical oxidation of salicylic acid (SA) has been studied on a glassy carbon electrode using cyclic voltammetry and differential pulse voltammetric (DPV) method. SA gives a single irreversible oxidation wave over the wide pH range studied. The irreversibility of the electrode process was verified by different criteria. The mechanism of oxidation is discussed. Using differential pulse voltammetry, SA yielded a well-defined voltammetric response in Britton-Robinson buffer solution, pH 2.37 at 1.088 V (versus Ag/AgCl). The method was linear over the SA concentration range: 1-60 μg ml⁻¹. The method was successfully applied for the analysis of SA as a hydrolysis product, in solid pharmaceutical formulations containing acetylsalicylic acid (ASA).     

Electroanalytical behaviour of 5-nitroorotic acid

The electroanalytical behaviour of 5-nitroorotic acid has been studied at several pH values, using several techniques (DC and DP polarography and CV). The 5-nitroorotic acid undergoes five irreversible diffusion-controlled reduction waves over entire pH range considered. The optimum conditions for determination of 5-nitroorotic acid-with the above technique are also studied.     

Voltammetric determination of hafnium with calconcarboxylic acid

The interaction of Hf(IV) with calconcarboxylic acid (1-(2-hydroxy-4-sulfo-1-naphtylazo)-3-naphtolic acid) was investigated by cyclic voltammetry varying various factors (pH, ionic strength, contents of ethanol and scan rate). Optimal conditions of Hf(IV) determination in the presence of calconcarboxylic acid were found: acetic buffer solution pH 2.6, scan rate 0.5 Vs⁻¹. The detection limit of Hf(IV) concentration was 2.46 × 10⁻⁷ mol L⁻¹. The influence of foreign ions on the Hf(IV) determination was studied. It was established that some metals like cadmium, nickel, zinc, copper and titanium could be determined with Hf(IV) simultaneously. The method of voltammetric determination of hafnium was tested on model solutions and used in the determination of Hf(IV) in terbium-base alloy.     

Electrochemical sensing of melamine with 3,4-dihydroxyphenylacetic acid as recognition element

A new electrochemical sensor for melamine with 3,4-dihydroxyphenylacetic acid as the recognition element is established. The results of Fourier Transform Infrared (FT-IR) spectra demonstrate that melamine may interact with 3,4-dihydroxyphenylacetic acid to form a complex mainly through the hydrogen-bonding interaction. The electrochemical behavior of 3,4-dihydroxyphenylacetic acid in the presence of melamine was studied. The anodic peak currents of 3,4-dihydroxyphenylacetic acid obtained by differential pulse voltammetry are linear with the logarithm of melamine concentrations in the range from 1.0 × 10⁻⁸ to 5.0 × 10⁻⁶ M with a linear coefficiency of 0.997. The detection limit is 3.0 × 10⁻⁹ M. The proposed method displayed an excellent sensitivity and was successfully applied to the determination of melamine in milk products.     

抗坏血酸在聚对羟基苯甲酸(poly-PHB)修饰玻碳上的电催化

过循环伏安制备了聚对羟基苯甲酸修饰的玻碳电极。考察了该电极对抗坏血酸的电催化性能。结果显示,聚对羟基苯甲酸修饰玻碳电极对抗坏血酸有很好的电催化作用。在修饰后的电极上产生的峰电流比修饰前的电极产生的峰电流大4倍,氧化峰电位负移189 mV。其氧化峰电流与抗坏血酸浓度在2.6×10-5~3.68 ×10-4mol/L范围内呈线性关系,相关性系数为0.9984,检测限为5×10-6 mol/L(S /N = 3)。在AA与UA共存的体系中,能排除多巴胺对抗坏血酸测定的干扰。     

Exploiting micellar environment for simultaneous electrochemical determination of ascorbic acid and dopamine

A simple and reliable method for simultaneous electrochemical determination of ascorbic acid (AA) and dopamine (DA) is presented in this work. It was based on the use of the cationic surfactant cetylpyridinium chloride (CPC) that enables the separation of the oxidation peaks potential of AA and DA. Cyclic voltammetry (CV) as well as pulse differential voltammetry (PDV) were used in order to verify the voltammetric behaviour in micellar media. In the cationic surfactant CPC, a remarkable electrostatic interaction is established with negatively charged AA, as a consequence, the oxidation peak potential shifted toward less positive potential and the peak current increased. On the other hand, the positively charged DA is repelled from the electrode surface and the oxidation peak potential shifts toward more positive potential in comparison to the bare electrode. Therefore, the common overlapped oxidation peaks of AA and DA can be circumventing by using CPC. Parameter that affects the E_pa and I_pa such as CPC concentration and pH were studied. Under optimised conditions, the method presented a linear response to AA and DA in the concentration range from 5 to 75 μmol L⁻¹ and 10 to 100 μmol L⁻¹, respectively. The proposed method was successfully applied to the simultaneous determination of AA and DA in dopamine hydrochloride injection (DHI) samples spiked with AA.     

Electrochemical behaviour of a lead electrode in phosphoric acid

 A lead electrode was studied in 6 and 12 M H₃PO₄. Oxidation of a freshly polished electrode occurred in the −0.5 to −0.3 V vs. SCE range, and led to PbHPO₄ growth on the electrode surface. The dissolution of this layer by electrochemical reduction occurred between −0.5 and −0.7 V. The influence of temperature (20 °C and 65 °C) was investigated and showed that the anodic and the cathodic peaks were increasing, and more markedly for the 12 M H₃PO₄. The ratio Q _cathodic/Q _anodic (Q=electrical charge flowing through the electrode) was equal or close to the unity at 20 °C and decreased as the temperature was increased. The influence of Cl⁻, Br⁻ and I⁻ ions was also evaluated. The addition of Cl⁻ and Br⁻ predominantly led to Pb₅(PO₄)₃Cl and Pb₅(PO₄)₃Br, respectively, while I⁻ led to a mixture of PbI₂ and PbHPO₄. Received: 18 July 1999 / Accepted: 2 November 1999     

咖啡酸苯乙酯在玻碳电极上的电化学行为研究

采用循环伏安法和差分脉冲伏安法研究了咖啡酸苯乙酯(CAPE)在玻碳电极表面上的电化学行为。在0.05 mol.dm-3磷酸盐缓冲溶液(PBS,pH=7.6)中,CAPE在0.229 V和0.214 V处呈现一对明显的氧化还原峰。考察了溶液pH值和扫描速率等因素对CAPE电化学行为的影响,结果表明,电化学过程中CAPE的电子转移数为2,参与反应的质子数也为2,且为吸附控制过程。在0.05 mol.dm-3磷酸盐缓冲溶液(PBS,pH=7.6)中,CAPE的氧化峰电流与其浓度在0.34～3.40μmol.dm-3范围内成线性关系,其响应灵敏度为0.88μA/μmol.dm-3,检出限为60 nmol.dm-3(S/N=3)。本研究建立了一种简单、快速、可灵敏测定CAPE的方法。同时对CAPE在玻碳电极上的电化学行为进行了较为详细的研究。     

Fabrication and characterisation of high performance polypyrrole modified microarray sensor for ascorbic acid determination

In this study, gold microelectrode array (Au/MEA) with electrode of 12 μm diameter was fabricated by photolithography technique. Subsequently, polypyrrole (Ppy) modified gold microarrays sensor (Ppy/Au/MEA) was prepared by cyclic voltammetry technique. The deposition potential range and number of cycles were optimised in order to get optimum thickness of Ppy film. Scanning Electron Microscope and Atomic Force Microscope investigations reveal that Ppy coating formed at 3 cycles is porous with thickness of 1.5 μm which exhibiting high catalytic current for ascorbic acid (AA) in square wave technique (SWV). In contrast to earlier sensors designs, these Ppy/Au/MEA sensors exhibits lower detection limit (LOD) of 10 nm towards AA at physiological conditions. It also exhibits enhanced sensitivity (2.5 mA cm⁻² mM⁻¹) and long range of linear detection limit from 10 nm to 2.8 mM. In the same way, polypyrrole modified macro Au (Ppy/Au/MA) biosensor was also fabricated and its electro catalytic property towards AA was compared with that of Ppy/Au/MEA. The Ppy/Au/MA exhibits sensitivity of only 0.27 mA cm⁻² mM⁻¹, LOD of 5 μM and linear range of 10 μM to 2.2 mM. Hence, our investigations indicate that the Ppy/Au/MEA could serve as highly sensitive sensor for AA than any of the earlier designs. So, the Ppy/Au/MEA electrode was utilised for determination AA in a wide variety of real samples.