Determination of Nickel in Fuel Ethanol Using a Carbon Paste Modified Electrode Containing Dimethylglyoxime

A mercury-free electrode chemically modified with carbon paste containing dimethylglyoxime was used for determination of nickel in fuel ethanol. The instrumental parameters and composition of the modified paste were optimized. The analytical curve for nickel determination from 5.0 × 10⁻⁹ to 5.0 × 10⁻⁷ mol L⁻¹ was obtained using 25 min of accumulation time. The detection limit and amperometric sensitivity obtained for this method were 2.7 × 10⁻⁹ mol L⁻¹ and 5.2 × 10⁸ μA mol⁻¹ L, respectively. The values for nickel concentration in four commercial samples of fuel ethanol were obtained in the range of 1.1 × 10⁻⁸ to 6.9 × 10⁻⁸ mol L⁻¹. A comparison to graphite furnace atomic absorption spectrometry (GFAAS) was performed for nickel determination in commercial samples of ethanol.     

Nafion修饰玻碳电极吸附伏安法直接测定邻氨基苯酚

在 p H=2 .0的 0 .1 mol/ L H3 PO4 缓冲溶液中 ,开路搅拌富集 2 min后 ,从 0 .0 0～ +1 .0 0 V阳极扫描 ,OAP在 Nafion修饰玻碳电极上出现一灵敏的氧化峰 ,峰电位位于 0 .44 V。该峰电流与 OAP在 1× 1 0 - 7～ 2 .5× 1 0 - 5mol/ L的浓度范围内有良好的线性关系 ,检出限为 1× 1 0 - 8mol/ L。对支持电解质的种类及 p H值、Nafion的用量、富集电位及时间、以及扫描速度等进行了优化 ,提出了一种直接测定邻氨基苯酚的电化学方法。将此方法用于水样中邻氨基苯酚的测定 ,取得了满意的结果     

Electrogenerated chemiluminescence using solution phase and immobilized tris(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)ruthenium(II)

Electrogenerated chemiluminescence (ECL) with tris(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)rathenium(II) (RuBPS) in solution and immobilized on an electrode surface is investigated. Flow injection analysis with a thin layer electrochemical cell modified for ECL detection is used to determine the analytical utility of solution phase RuBPS and RuBPS immobilized in a cationic polypyrrole derivative. The solution phase reaction of RuBPS with oxalate is investigated with regard to the dependence of ECL emission on RuBPS concentration, carrier stream flow rate, and pH. In the parameter range studied, ECL intensity is not linear with the concentration of RuBPS in the sample. A maximum ECL intensity is observed with a RuBPS concentration of approximately 250 M. Slower linear velocities give greater ECL intensities which is the opposite of what is observed for Ru(bpy) ₃ ³⁺ and oxalate. Greater ECL intensity is observed at lower pHs for oxalate and at higher pHs for proline. RuBPS ECL with oxalate yields a working curve with a linear range from 0.1–100 M oxalate. Solution phase ECL is observed for RuBPS and other amines such as NADH, proline, tripropylamine, and antibiotics including streptomycin and gentamicin. RuBPS is also immobilized by electrochemical polymerization of 1-methyl-3-(pyrrol-1-ylmethyl)pyridinium chloride (MPP) in the presence of RuBPS. This polymer-modified electrode yields ECL for oxalate and for amines.Deceased     

微电极研究 ⅩⅢ.聚苯胺修饰微盘电极的研究

用恒电流法在盐酸介质中以最佳聚合条件将聚苯胺修饰在Ｐｔ微盘电极上。制得的聚苯胺修饰微盘电极对ｐＨ有能斯特响应，稳定性好，用于样品测定，结果满意。     

Functional tuning of nucleic acids by chemical modifications: tailored oligonucleotides as drugs,devices, and diagnostics

Chemical modifications of nucleic acids present vast opportunities for extending the functions and properties of these biomolecules. In general, efforts invested in this direction pertain to the introduction of reactive functional groups for further derivatizations of oligonucleotides with numerous reporter groups and for equipping nucleic acids with catalytic chemical moieties. This review deals with representative chemical modifications in the nucleobases, sugars, and the phosphate ester backbone and their application from novel catalytic RNA selection to nucleic acid-based biosensors.     

舒乐安定在铂离子注入修饰电极上的电化学行为及其应用

舒乐安定在0.1 mol/L NH3-NH4Cl缓冲溶液(pH 9.40)中,用线性扫描伏安法,在Pt/GC离子注入修饰电极上,形成一良好的线性扫描伏安还原峰,峰电位Ep=-0.70V(vs.SCE)。其峰电流与舒乐安定浓度在3.0×10-9-1×107和1×10-7-1.5×10-6mol/L范围内呈线性关系,相关系数均为0.9999,检出限为3.0×10-9mol/L。并用于片剂的测定,回收率在96.5％～98.5％之间,结果是可靠的。用循环伏安法研究了体系的性质。实验表明,电极过程为不可逆吸附。用AES、XPS和SEM等表面分析方法证明,Pt离子确实注入到玻碳基体电极表面,Pt以原子态存在,催化了舒乐安定的还原。     

压汞法测量玻璃毛细孔中的水和正癸烷

水在固体表面或在毛细孔玻璃中的性质,一直是人们感兴趣的问题。而靠近固体表面的水,其性质不同于体相(Bulk)水,也是为人所知的事实。已经知道,邻近水的热容、密度、粘度、电导及结构等都不同于体相水。但邻近水的厚度究竟为多少,或者说,这种固体表面对水的性质影响究竟是长程的还是短程的,目前还没有统一的结论。用压汞法测量多孔物质的孔体积,是人们已熟知的方法,但还没有人将其用于测量液体在毛细孔中的体积、密度等行为。我们尝试了用压汞法,测量具有确定孔径的毛细孔玻璃(CPG),在吸附了不同量水后孔体积的变化,进而计算了不同吸附层的水在CPG中的体积、密度。此外还测定了载有不同量正癸烷后,CPG孔体积的变化。     

Development of an acetylspiramycin sensor based on a single-walled carbon nanotubes film electrode

A simple and sensitive sensor is described for the determination of acetylspiramycin (ASPM) based on a single-wall carbon nanotubes (SWNTs)-dihexadecyl hydrogen phosphate (DHP) film coated glassy carbon electrode (GCE). Compared with a bare GCE, the SWNTs-DHP film modified GCE exhibits excellent enhancement effects on the electrochemical oxidation of ASPM. A well-defined oxidation peak of ASPM occurs at 0.89 V in 0.1 mol·L⁻¹ phosphate buffer (pH 5.5), which was used to determine ASPM. The electrochemical behavior of ASPM at the SWNTs-DHP modified GCE was examined by cyclic voltammetry and differential pulse voltammetry. The experimental parameters were optimized and a direct electrochemical method for the determination of ASPM is proposed. Under optimum conditions, the oxidation peak current is linear to the concentration of ASPM in the range of 5.0–100 μg·mL⁻¹, with a detection limit of 1 μg·mL⁻¹. The SWNTs-DHP film modified electrode also provides an efficient way of eliminating interferences from some inorganic species in the solution. This sensor was successfully utilized to determine ASPM in drugs.     

Pentacyanoferrates(II) on the surface of organomodified silica gel: The matrix effect

Pentacyanoferrate(II) absorbed on a silica gel surface previously modified with 3-aminopropyl and 3-imidazolylpropyl groups were characterized by¹³C MAS/NMR, FT-IR, Mössbauer spectroscopy, and cyclic voltammetry. FT-IR and¹³C MAS/NMR data indicated that the pentacyanoferrate(II) complex is bonded to the surface by the nitrogen atom of the functional group. The differences in the isomeric shifts, the quandrupole splittings and the midpoint potentials of the adsorbed complexes in comparison with the model complexes were attributed to the matrix polar effect—i.e., the interaction of the complex with polar groups on the silica surface.     

三元重叠色谱峰面积的定量方法

本从色谱峰的ＥＭＧ模型出发，通过对重叠色谱峰的模拟和回归分析，提出了一种三元重叠色谱峰的面积的定量方法，三元重叠色谱峰的每一个峰面积可以由峰面积比和总面积求得，此法所需的数据都由实验色谱图上测得，峰面积计算结果的相对误差小于±５％，适用于相对峰谷为５０％－９５％的三元重叠色谱峰面积的定量。