Preparation and properties of insoluble films of cyclodextrin condensation polymers

The preparation and properties of smooth and stable films of cyclodextrin polymers are described. The commercially available water soluble prepolymers of-, -, and-cyclodextrin of low molecular masses were crosslinked with glutaric dialdehyde. Side-chain unreacted aldehyde groups were reduced with sodium borohydride. For the-cyclodextrin polymer, optimum film performance was found for a 1:10 mass ratio of glutaric dialdehyde to prepolymer, which corresponds to a molar ratio of glutaric dialdehyde to cyclodextrin units of about 1.75: 1. Such films, of thickness 2.4 µm, were prepared on metallic or glassy-carbon substrates for characterization by scanning-electron microscopy, and for studies with the electrochemical quartz-crystal microbalance.     

Amperometry of Heparin Polyion Using a Rotating Disk Electrode Coated with a Plasticized PVC Membrane

Electrochemical method of detection of heparin polyion was developed based on voltammetry of heparin on a rotating glassy carbon (GC) electrode coated with a plasticized PVC membrane. The membrane was deposited on the GC disk by spin‐coating technique using a mixture of solutions of PVC in tetrahydrofuran, and 1,1′‐dimethylferrocene (DMFc) and hexadecyltrimethylammonium tetrakis(4‐chlorophenyl)borate (HTMATPBCl) in o‐nitrophenyl octyl ether. UV/vis reflection spectrometry was used to evaluate the membrane thickness, which exhibits a linear correlation with the membrane resistance measured by impedance spectroscopy. It is shown that this electrode can be used for amperometric or coulometric detection of heparin in aqueous samples of medically relevant concentrations (1–10 U mL^?1), with a detection limit of 1.4 U mL^?1. Evidence is provided indicating that the current determining step is the reversible adsorption of the ion‐pair of heparin polyion with HTMA⁺ cation at the membrane/aqueous electrolyte interface, which is driven by oxidation of DMFc at the GC/membrane interface.     

简易型离子选择电极-流动注射分析仪的研制及卤水中氯、溴和碘的连续测定

本文设计研制了简单实用的流通池,组装了简易型离子选择电极—流动注射分析仪,对体系的分析特点和影响因素进行了考察。此装置性能可靠,能满足简单流注分析的需要,并建立了卤水中Cl~-、Br~-和I~-的连续测定方法。     

Resistance to Surfactant and Protein Fouling Effects at Conducting Diamond Electrodes

Boron‐doped diamond thin‐film electrodes display negligible fouling effects in the presence of high levels of surface‐active materials, including proteins. Dramatic improvements in the stability of the analyte response (compared to common glassy carbon and carbon paste electrodes) are illustrated using bovine serum albumin (BSA), gelatin, and Triton X‐100 in connection with repetitive square‐wave voltammetric (SWV) measurements. The voltammetric response of ascorbic acid at the diamond electrode exhibits negligible shifts in peak potentials and minimal depressions of current signals over a wide range of surfactant concentrations (0–750 ppm). For example, the diamond electrode exhibited 70, 50 and 60 mV potential shifts for 10 repetitive voltammetric scans in the presence of 100 ppm BSA, gelatin and Triton X‐100, respectively, compared to 120, 190, and 280 mV shifts observed at the glassy carbon electrode. Furthermore, only 4.3 and 6.2% of the initial current decays were observed in the presence of 100 ppm Triton X‐100 and gelatin, respectively (compared to 45.2 and 34.4% diminutions at the glassy carbon electrode). Such improved performance was also confirmed from the SWV measurements of uric acid, dihydroxyphenylacetic acid, and catechol. The greatly improved resistance to surfactant interference reflects the fact that the as‐grown diamond thin film, composed of oxide‐free and hydrogen‐terminated surface, has a relatively lower surface energy and minimal electrostatic attributes, either specific or general, so that little adsorption of surface‐active agents occurs. The topographic AFM images of the diamond electrode surface confirm a negligible BSA fouling effect after repetitive SWV measurements. Such enhanced antifouling features make diamond electrodes very attractive for numerous real‐life electroanalytical applications.     

Analyzing electrochemical noise with Chebyshev’s discrete polynomials

The principles underlying a novel method intended for analyzing experimental data obtained when studying fluctuation processes are considered. The method in question is Chebyshev’s spectroscopy. The application of this method allows one to determine statistic characteristics of steady-state electrochemical noise against the background of severe deterministic interference without invoking the procedure of the fitting of the initial data. The potentialities of this novel method, which is intended for treating noise experiment, are demonstrated by examining model examples and analyzing the electrochemical noise generated by a lithium electrode placed in an aprotic organic electrolyte.     

Direct Electrochemistry of Cytochrome C on the Glassy Carbon Electrode Modified with 1-Pyrenebutyric Acid/MWNTs

With 1-Pymnebutyric acid （PBA） and multiwalled carbon nanotubes （MWNTs）, glassy carbon electrode modified was successfully prepared. In phosphate buffer solution （pH 7,0）, the direct electrochemistry of cytochrome C （Cyt C） was realized. In the cyclic voltammetry experiment two pairs of redox peaks ofCyt C were observed at 0.018 V and -0.314 V （vs. SCE）, respectively. The redox reaction at 0.018 V was diffusion controlled, while the redox reaction at -0.314 V was adsorption controlled.     

离子注入修饰电极检测硝基苯

离子注入是一种新技术，可按人们的意愿和需要，将不同的离子注入不同的基本电极表面，制成具有催化活性强，稳定性高，重现性好等特点的修饰电极。作者研究了离子注入钴和注入镍的玻碳电极在０．１ｍｏｌ／ＬＨＡｃ－ＮａＡｃ缓冲溶液中硝基苯的行为及测定。     

溶胶-凝胶-钴-邻菲啰啉修饰电极对一氧化氮的电催化氧化及其测定

报道了溶胶 凝胶 钴 邻菲口罗啉膜修饰电极的制备方法及其在一氧化氮(NO)检测中的应用,采用循环伏安法(CV)研究修饰电极的电化学特性,差示脉冲伏安法(DPV)对NO进行检测。该修饰电极对NO的电化学氧化具有很好的催化作用,使其氧化电位负移了210mV,氧化峰电流与NO浓度在5.6×10-8～2.8×10-5mol/L范围内呈良好的线性关系,相关系数r=0.999,检测限为1.4×10-8mol/L,且生物体内常见的干扰物质如抗坏血酸、NO2-和儿茶酚胺类神经递质的代谢物等不干扰测定。     

聚苯胺尿酸酶电极性能的研究

依据pH对聚苯胺尿酸酶电极最大响应电流的影响, logim～pH图表明尿酸酶电极的催化活性只与其电离基团的碱性形式有关. 扫描电镜的结果表明, 聚苯胺尿酸酶电极的稳定性与其制备方法有关. 电化学法固定的尿酸酶电极具有高的稳定性.