直接热分解法制备的碳载Pt-Sn催化剂对乙醇氧化的电催化性能

以Pt( NO3)2和SnO为前驱体采用直接热分解法制备了碳载Pt-Sn (Pt-Sn/C)催化剂.用X射线衍射(XRD)、透射电镜(TEM)和X射线光电子能谱(XPS)等技术对催化剂进行了表征,用循环伏安法和CO溶出等方法研究了催化剂对乙醇氧化的电催化性能.结果表明,Pt-Sn/C催化剂中的Pt-Sn粒子具有Pt-S...     

VB_6在微电极上的电化学行为及测定

VB_6又称吡哆素,是一种含吡哆醇、吡哆醛或吡哆胺的B族维生素.目前测定的方法主要有:微生物法、高效液相色谱法、光谱法、电位法、修饰电极伏安法~([1,2])等.本实验采用碳纤维微电极,利用多种电化学方法循环伏安法(CV)、示差脉冲伏安法(DPV)、线性扫描伏安法(LSV)等研究了VB_6的电化学行为,并对药物中的VB6进行了检测.该方法灵敏度高、操作简便、快捷,具有一定的应用价值,并为今后研究纳米电极测定VB_6奠定基础.     

Ag_2Se纳米材料的制备方法

对纳米Ag2Se的化学制备方法进行了概述,着重介绍了模板法、声化学法、水(溶剂)热法、光照合成法、微乳状液法等;展示了新近得到的不同形貌和性质的As2Se纳米晶体;并对其发展趋势和应用前景进行了展望.     

FeY型分子筛的高效制备及非均相Fenton催化降解性能

改进传统水热合成法,以湿凝胶晶化法高效制备了具有FAU结构的含铁Y型分子筛.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)、电感耦合等离子体发射光谱(ICP)和X射线光电子能谱(XPS)等方法对产物结构、形貌及组成等进行了表征,并与传统水热合成法及离子交换法制备的含铁Y型分子筛进行了比较.将该分子筛作为催化剂构建了非均相Fenton体系,该体系对亚甲基蓝染料具有良好的催化降解性能,考察了溶液初始pH值、H_2O_2用量以及催化剂用量等因素对Fenton催化性能的影响,并研究了催化剂的循环再生性能.     

低价铈复盐微波辐射化学氧化还原合成法

利用氧化还原原理, 采用微波辐射法合成了低价铈复盐, 通过XRD、 TG-DTG及场发射扫描电镜(FE-SEM)等方法对样品的组成结构进行了分析表征, 并讨论了合成条件对产物的影响以及氧化还原机理. 研究表明采用该法合成低价铈复盐具有方法简单、易于操作、高效节能等特点.     

乳粉中蛋白质含量测定条件的探讨

针对乳粉法的不足,结合GB/T5009. 5-2003方法 (食品法 )对消化液的用量、蒸馏接收时间、硫酸铜和硫酸钾的用量等实验条件进行最佳选择。改进后的方法与食品法对低蛋白含量乳粉的测定结果无显著性差异 (p>0.05),对高蛋白含量乳粉的测定结果有差异(0.005>p>0. 002)。该方法对高蛋白含量乳粉的检出更完全。     

主成分回归一紫外光度法同时测定盐酸西替利嗪和苯甲酸钠

提出了一种用紫外光度法同时测定盐酸西替利嗪和苯甲酸钠的方法.在pH 4.56的B-R缓冲溶液中对盐酸西替利嗪和苯甲酸钠两组分混合溶液进行吸光度测定,所得的重叠光谱数据用主成分回归法(PCR)和偏最小二乘法(PLS)等化学计量学方法进行处理,结果表明主成分回归(PCR)的预报误差最小.对实际样品进行测定,回收率为88.8...     

隐丹参酮的电化学性质及其与DNA相互作用的研究

利用循环伏安法(CV)、线性扫描伏安法(LSV)、方波伏安法(OSWV)等电化学技术研究了隐丹参酮在玻碳电极(GCE)上的电化学氧化过程,并用计时电量法和恒电位库仑电解法等对其在电极表面的吸附行为及氧化还原机理进行了探讨.此外利用自组装DNA修饰玻碳电极研究了隐丹参酮与DNA之间的相互作用.     

流动注射-原子吸收分光光度法测定彩电荧光屏壁玻璃中钾钠钙镁铁

本文应用流动注射分析-原子吸收分光光度法(FLA-AAS)测定彩电荧光屏壁玻璃中的钾、钠、钙、镁、铁的含量、对方法中可能存在的各种影响因素、干扰情况及其消除等进行了较为详细的研究.应用所建立的方法对样品测定取得了满意结果.本文对所建立的FIA-AAS法与常规AAS法进行了比较及讨论     

微波等离子体炬-质谱法测定饮用水中微量钙

以微波等离子体炬(MPT)作为离子源,廉价离子阱为质量分析器,建立了用常见有机质谱仪测定饮用水中微量钙的方法.实验考察了MPT工作气流量、载气流量等参数对待测元素信号的影响,并对这些参数进行了优化.在优化的实验条件下,采用标准加入法对井水、自来水及瓶装饮用矿泉水等样品中的微量钙进行了测定.结果表明,该方法的检出限(LOD)为3.88 ng/L,相对标准偏差(RSD)为2.87%~8.04%,加标回收率(R)为101.3%~115.1%.     

碳纳米管的最新制备技术及生长机理

结合笔者的工作综述了碳纳米管的制备技术及生长机理的最新研究进展，重点介绍了近两年来碳纳米管制备的进展情况，包括传统制备方法的改进（电弧放电法、化学气相沉积法和激光蒸发法）、新型制备技术、特殊结构的碳纳米管制备；同时探讨了碳纳米管的各种生长机理；最后提出了碳纳米管制备技术和生长机理的发展方向。     

Nonmevalonate terpene biosynthesis enzymes as antiinfective drug targets: substrate synthesis and high-throughput screening methods

The nonmevalonate isoprenoid pathway is an established target for antiinfective drug development. This paper describes high-throughput methods for the screening of 2C-methyl-D-erythritol synthase (IspC protein), 4-diphosphocytidyl-2C-methyl-D-erythritol synthase (IspD protein), 4-diphosphocytidyl-2C-methyl-D-erythritol kinase (IspE protein), and 2C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF protein) against large compound libraries. The assays use up to three auxiliary enzymes. They are all monitored photometrically at 340 nm and are robust as documented by Z-factors of >or=0.86. 13C NMR assays designed for hit verification via direct detection of the primary reaction product are also described. Enzyme-assisted methods for the preparation, on a multigram scale, of isoprenoid biosynthesis intermediates required as substrates for these assays are reported. Notably, these methods enable the introduction of single or multiple 13C labels as required for NMR-monitored assays. The preparation of 4-diphosphosphocytidyl-2C-methyl-D-erythritol 2-phosphate in multigram quantities is described for the first time.     

Recent advances in metal‐organic frameworks and covalent organic frameworks for sample preparation and chromatographic analysis

In the field of analytical chemistry, sample preparation and chromatographic separation are two core procedures. The means by which to improve the sensitivity, selectivity and detection limit of a method have become a topic of great interest. Recently, porous organic frameworks, such as metal‐organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in this research area because of their special features, and different methods have been developed. This review summarizes the applications of MOFs and COFs in sample preparation and chromatographic stationary phases. The MOF‐ or COF‐based solid‐phase extraction (SPE), solid‐phase microextraction (SPME), gas chromatography (GC), high‐performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) methods are described. The excellent properties of MOFs and COFs have resulted in intense interest in exploring their performance and mechanisms for sample preparation and chromatographic separation.     

Sample preparation with solid phase microextraction and exhaustive extraction approaches: Comparison for challenging cases

In chemical analysis, sample preparation is frequently considered the bottleneck of the entire analytical method. The success of the final method strongly depends on understanding the entire process of analysis of a particular type of analyte in a sample, namely: the physicochemical properties of the analytes (solubility, volatility, polarity etc.), the environmental conditions, and the matrix components of the sample. Various sample preparation strategies have been developed based on exhaustive or non-exhaustive extraction of analytes from matrices. Undoubtedly, amongst all sample preparation approaches, liquid extraction, including liquid–liquid (LLE) and solid phase extraction (SPE), are the most well-known, widely used, and commonly accepted methods by many international organizations and accredited laboratories. Both methods are well documented and there are many well defined procedures, which make them, at first sight, the methods of choice. However, many challenging tasks, such as complex matrix applications, on-site and in vivo applications, and determination of matrix-bound and free concentrations of analytes, are not easily attainable with these classical approaches for sample preparation.     

High resolution separation methods for the determination of intact human erythropoiesis stimulating agents. A review

Human erythropoietin (hEPO), a hormone involved in the formation of red blood cells, is a 30 kDa glycoprotein with a high carbohydrate content. The production of recombinant hEPO has made possible its widespread therapeutic use and its banned use in competition sports. Methods to analyze EPO and other erythropoiesis stimulating agents (ESAs) are necessary for the characterization and quality control of these biopharmaceuticals and also for doping control. In this paper, high resolution separation methods, namely high performance liquid chromatography (HPLC) and capillary electrophoresis (CE), with special attention to CE-coupled mass spectrometry, are reviewed. The usefulness of these techniques when applied in different modes to separate the glycoprotein isoforms, aggregates or excipients are detailed. In addition, sample preparation methods that have been applied to ESA samples for subsequent determination by HPLC or CE, as well as the potential compatibility of other preparation methods, are discussed. Applications of the HPLC and CE methods regarding regulatory considerations for biopharmaceuticals analysis, with emphasis on biosimilars, and doping control are also included. Finally, limitations of the present methods and their possible solutions are considered.     

气相氟化合成氢氟烯烃催化剂的研究进展

氢氟烯烃(HFOs)是重要的精细化工中间体, 气相氟化合成HFOs具有可连续生产、 避免对反应釜的严重腐蚀等优点, 简化生产工艺已成为国内外生产氟化工产物的重要方法. 本文简要介绍了合成HFOs的常见催化反应类型以及反应机制, 并按照主催化剂成分分类概述气相氟化合成所用的催化剂, 介绍了各类催化剂的传统制备方法(如沉淀法等)和新的制备方法(如自组装法、 溶液燃烧合成法、 硬模板法、 静电纺丝法等), 以及催化性能, 提出了该催化剂的未来发展方向.     

纳米纤维素的制备

在纳米尺寸范围操控纤维素分子及其超分子聚集体,结构设计并组装出稳定的多重花样,由此创制出具有优异功能的新纳米精细化工品、新纳米材料,是纤维素科学的前沿领域和热点。为了研究当前制备纳米纤维素的现状和发展方向,简述了纳米纤维素化学基础,介绍了三类纳米纤维素：纳米纤维素晶体（晶须）、纳米纤维素复合物和纳米纤维素纤维,重点综述了纳米纤维素的五种制备方法：化学法制备纳米纤维素晶体和晶须、生物法制备细菌纤维素、物理法制备微纤化纳米纤维素、人工合成纳米纤维素和静电纺丝制备纤维素纤维,讨论了各种制备方法的优点和缺点,指出开展纳米纤维素超分子的可控结构设计、立体与位向选择性控制与制备、分子识别与位点识别等自组装过程机理、多尺度结构效应的形成机理等基础理论性研究是主要研究基础,新型的、绿色、低能耗、快速、高效的制备方法是纳米纤维素制备方法的发展方向。     

维生素E的催化合成路线分析

维生素E具有多种特异的生理活性,同时也是一种优良的抗氧化剂,已经逐渐成为维生素领域中的焦点,市场需求不断增加。目前合成维生素E占据市场的80%以上,提升维生素E的产量和生产效率势在必行。天然维生素E包括四种生育酚类物质和四种生育三烯酚类物质,其中α-生育酚含量最大,生理活性也最高。本综述简要介绍α-生育酚的合成路线,其中包括2, 3, 5-三甲基氢醌和异植物醇的合成以及它们二者缩合的反应。本文着重阐述路线的设计和催化剂的选择,并对存在的问题及潜在的解决办法进行评述和展望。     

Analytical methods for the assessment of endocrine disrupting chemical exposure during human fetal and lactation stages: A review

In the present work, a review of the analytical methods developed in the last 15 years for the determination of endocrine disrupting chemicals (EDCs) in human samples related with children, including placenta, cord blood, amniotic fluid, maternal blood, maternal urine and breast milk, is proposed. Children are highly vulnerable to toxic chemicals in the environment. Among these environmental contaminants to which children are at risk of exposure are EDCs —substances able to alter the normal hormone function of wildlife and humans—. The work focuses mainly on sample preparation and instrumental techniques used for the detection and quantification of the analytes. The sample preparation techniques include, not only liquid–liquid extraction (LLE) and solid-phase extraction (SPE), but also modern microextraction techniques such as extraction with molecular imprinted polymers (MIPs), stir-bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid–liquid microextraction (DLLME), matrix solid phase dispersion (MSPD) or ultrasound-assisted extraction (UAE), which are becoming alternatives in the analysis of human samples. Most studies focus on minimizing the number of steps and using the lowest solvent amounts in the sample treatment. The usual instrumental techniques employed include liquid chromatography (LC), gas chromatography (GC) mainly coupled to tandem mass spectrometry. Multiresidue methods are being developed for the determination of several families of EDCs with one extraction step and limited sample preparation.     

二茂铁基嵌段共聚物制备及自组装研究

本文综述了近年来二茂铁基嵌段共聚物制备及自组装的研究进展.对环状二茂铁单体的活性阴离子引发开环聚合(ROP)、过渡金属催化开环聚合(ROP)及聚合机理和聚合物自组装胶束的结构、表征和潜在应用作了介绍.