皮革中六价铬含量的IUC-18测定法

Ｃｒ(ＩＩＩ)是制革业最重要的鞣剂 ,制革业所用的Ｃｒ(ＩＩＩ)鞣剂由Ｃｒ(ＶＩ)还原而得到。皮革中除Ｃｒ(ＩＩＩ)外 ,还可能含有微量的Ｃｒ(ＶＩ) ,目前欧盟等国要求Ｃｒ(ＶＩ)的含量小于 5ｍｇ/ｋｇ[1 ] ;国内则还没有分析测定皮革中六价铬的国家标准 ,本文介绍六价铬的ＩＵＣ - 1 8国际标准分析方法 (ＩＵＣ ,Ｉｎｔｅｒ ｎａｔｉｏｎａｌＵｎｉｏｎｏｆＣｈｅｍｉｓｔｒｙ) ,并分析了该方法的不足及改进途径。1　实验部分ｐＨ7 5～ 8 0、惰性气体保护下用磷酸盐缓冲溶液浸取皮革的六价铬 ,六价铬将 1 ,5 二苯卡巴肼氧化为 1 ,5 二苯…     

Parameterization of OPLS-AA force field for the conformational analysis of macrocyclic polyketides

The parameters for the OPLS-AA potential energy function have been extended to include some functional groups that are present in macrocyclic polyketides. Existing OPLS-AA torsional parameters for alkanes, alcohols, ethers, hemiacetals, esters, and ketoamides were improved based on MP2/aug-cc-pVTZ and MP2/aug-cc-pVDZ calculations. Nonbonded parameters for the sp(3) carbon and oxygen atoms were refined using Monte Carlo simulations of bulk liquids. The resulting force field predicts conformer energies and torsional barriers of alkanes, alcohols, ethers, and hemiacetals with an overall RMS deviation of 0.40 kcal/mol as compared to reference data. Densities of 19 bulk liquids are predicted with an average error of 1.1%, and heats of vaporization are reproduced within 2.4% of experimental values. The force field was used to perform conformational analysis of smaller analogs of the macrocyclic polyketide drug FK506. Structures that adopted low-energy conformations similar to that of bound FK506 were identified. The results show that a linker of four ketide units constitutes the shortest effector domain that allows binding of the ketide drugs to FKBP proteins. It is proposed that the exact chemical makeup of the effector domain has little influence on the conformational preference of tetraketides.     

DTA研究二水二草酸合铬酸钾的顺、反异构化

顺—反异构体的研究,在配合物化学中占有重要的地位。二水二草酸合铬酸钾这一配合物顺、反异构体的制备和异构化现象的研究已有报导,但多限于水溶液体系。也有关于该配合物热稳定性和热分解动力学研究的报导但对固相中该配合物异构体转变的研究尚未见报导。本文利用DTA方法,对二水二草酸合铬酸钾顺、反异构体的制备以及固相中异     

Computer-aided multichannel detection in high-performance liquid chromatography

Summary The development of a computer-aided rapid-scanning detector for HPLC based on the linear photodiode array UV-visible spectrophotometer is described. Chomatograms monitored at up to three wavelengths, with automatic capture of spectra for eluted peaks and post-run processing of spectral data to generate log₁₀ (A) spectra, second derivative and fourth derivative spectra, are described. Methods are reported for the analysis of forensic samples of diacetylmorphine (heroin) in the presence of the degradation products and potential contaminants caffeine, papaverine, 6-acetylcodeine, thebaine, 6-acetyl-morphine, procaine and morphine separated by HPLC. The novel use of second and higher derivative spectra for the qualitative characterisation of drugs and contaminants separated by HPLC is described.Presented at the 14th International Symposium on Chromatography London, September, 1982     

微流控芯片技术在生命科学研究中的应用

微流控芯片最初起源于分析化学领域,是一种采用精细加工技术,在数平方厘米的基片,制作出微通道网络结构及其它功能单元,以实现集微量样品制备、进样、反应、分离及检测于一体的快速、高效、低耗的微型分析实验装置.随着微电子及微机械制作技术的不断进步,近年来微流控芯片技术发展迅猛,并开始在化学、生命科学及医学器件等领域发挥重要作用.本文首先简单介绍了微流控芯片制作材料和工艺,然后主要阐述了其在蛋白质分离、免疫分析、DNA分析和测序、细胞培养及检测等方面的应用进展.     

Multi-walled carbon nanotubes as a solid-phase extraction adsorbent for the determination of chlorophenols in environmental water samples

Multi-walled carbon nanotubes (MWCNs) are used as adsorbent for solid-phase extraction (SPE) of several chlorophenols (CPs). CPs were adsorbed on MWCNs cartridge, then desorbed with pH 10.0 methanol, finally determined by HPLC. Under the optimized conditions, detection limits of 0.08-0.8 ng mL(-1) were obtained. The method had been applied to analyze the five CPs in tap water and river water.     

Spatially resolved characterization of PEFCs using simultaneously neutron radiography and locally resolved impedance spectroscopy

A method for performing neutron radiography and locally resolved impedance spectroscopy simultaneously in situ in an operating polymer electrolyte fuel cell (PEFC) is presented. The new method provides concurrently spatially resolved information about the local cell performance, the locally limiting processes, and the liquid water distribution. Information about the impact of water on cell performance and limiting processes can be gained in situ on a local scale in an operating PEFC. The method was applied to a PEFC operated on pure H₂/O₂ in co-flow mode under low humidity operating conditions. The results show that in co-flow mode strong flooding and severe drying can occur at the very same time in different sections of a PEFC.     

高效毛细管电泳前沿分析法研究酸性药物那格列奈与人血浆白蛋白的结合

用高效毛细管电泳前沿分析法研究了酸性药物那格列奈与人血浆白蛋白的结合常数、结合位点和结合率。使用未涂层的毛细管柱 (4 0cm× 5 0 μmi.d .;有效柱长 32cm) ,磷酸盐缓冲溶液 (pH 7.4 ,离子强度0 .17)为背景溶液 ,在紫外检测波长 2 14nm、运行电压 18kV和重力进样 10 0s的条件下 ,利用那格列奈谱峰的平台高度和游离药物浓度的良好线性关系 (r>0 .999,n =6 ) ,测定了那格列奈的游离药物浓度。固定药物浓度 (2 0 0 μmol L ,2 5 0 μmol L) ,考察不同的蛋白质浓度对结合的影响 ;固定蛋白质浓度 (10 0 μmol L) ,考察不同的药物浓度对结合的影响。实验数据采用非线性拟和程序进行处理 ,得到了那格列奈的蛋白质结合参数。高效毛细管电泳前沿分析法测定的数据重现性良好 (RSD <2 .5 % ,n =3) ,在药代动力学和药效学研究方面具有简便、准确的优点。     

Optimisation of the connection between TA-MS systems together with improved data interpretation for TA-MS applications

TA-MS provides chemical and thermal response information. In order for this information to be meaningful sampling must be performed with minimum dead volume and without cold spots. Dead volume leads to response lag and peak broadening. Cold spots result in sample condensation, leading to inaccurate data and potentially inlet blockage. This paper describes a hot zone inlet system and 'in-situ' probe both of which provide fast response, zero dead volume sampling directly to the MS. The paper also discusses data interpretation methodologies and introduces 'soft ionisation' as a means of providing simplified analysis of complex mixtures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Amperometric detection of hydrazine by cyclic voltammetry and flow injection analysis using ruthenium modified glassy carbon electrodes

Glassy carbon electrodes modified with (5-amino-1,10-phenanthroline)bis(bipyridine)ruthium(II) chloride hydrate, [(bpy)₂Ru(5-phenNH₂)]Cl₂·H₂O, are shown to oxidize hydrazine with excellent sensitivity. The presence of an amine group on the ruthenium complex facilitates electropolymerization onto the electrode surface. Using cyclic voltammetry, a large catalytic current is observed upon oxidation of hydrazine in phosphate buffer (pH 5.0), compared to the current obtained from the ruthenium-modified electrode with no hydrazine present. The sensitivity of cyclic voltammetry is sufficient for obtaining a linear calibration curve for hydrazine over the range of 10⁻⁵ to 10⁻² M. Hydrodynamic amperometry was used to determine the working potential for flow injection analysis. The limit of detection for hydrazine was determined to be 8.5 μM using FIA. The thickness of these films was shown to increase linearly with the number of electropolymerization cycles, in the range of 1000-2500 nm for 5-20 cycles, respectively, using Rutherford backscattering spectrometry (RBS). RBS analysis also suggests that the film is multilayered with the outermost layers containing a high ruthenium concentration, followed by layers where the concentration of ruthenium decreases linearly and approaches zero at the electrode surface.