气相色谱直接进样法分析环己烷氧化废液中的有机酸

环己烷氧化废液经酸化、抽滤等预处理后 ,采用气相色谱直接进样法分离了样品中的 1 0种有机酸 ,并测定了其含量。测定废液中各有机酸的回收率在 95 %～ 1 0 5 %之间。气相色谱固定相为 5 %新戊二醇己二酸酯 +0 .2 %磷酸/1 0 1酸洗白色担体。     

气相色谱法测定环己烷中甲酸

提出了测定环己烷中甲酸含量的气相色谱法,采用热导池检测器,癸二酸/GDX103不锈钢填充柱(2m×2mm),优化了色谱条件,测得检出限(3S/N)为11 0 mg·kg-1,甲酸的质量浓度在10.0～100.0 g·L-1范围呈线性关系,测得加标回收率在96.0%～104.3%之间,对20.0,100.0 g.L-1甲酸标准测定7次,相对标准偏差分别为3.2%和1.9%,符合环己烷工艺中甲酸含量测定的技术要求.     

氧气催化氧化环己烷

本文系统综述了O₂氧化剂用于环己烷催化氧化体系的研究进展,包括金属配合物催化、金属纳米粒子催化、金属氧化物粒子催化、分子筛催化、碳材料催化、光促进催化、杂多酸催化、金属-有机骨架材料催化等。本文认为研究、开发以O₂为氧化剂,高活性高选择性的非均相环己烷催化氧化体系将成为今后环己烷催化氧化研究的主要方向,尤其是多金属甚至多元素复合体系。本综述不仅对开发高催化活性高选择性的环己烷催化氧化体系,改进目前工业上的环己醇环己酮制备工艺具有重要的参考价值,而且还对其他烃类C-H键和C-C键高效催化氧化体系甚至其他氧化体系的研究与开发也具有重要的参考价值。     

醋酸对环己烷气相氧化脱氢产物选择性影响的研究

以α1-VOPO4相为催化剂, 在环己烷气相氧化脱氢反应中, 通过在原料中加入醋酸可控制反应产物的分布. 研究了不同醋酸量对目标产物选择性的影响, 醋酸在反应体系中优于环己烷吸附在α1-VOPO4催化剂的表面上, 使催化剂表面形成孤立的活性中心, 避免了产物环己烯的深度氧化. 反应温度为450 ℃, 醋酸与环己烷的摩尔比为12.9∶1时, 环己烷的转化率为6.9%, 环己烯的选择性为100%.     

环己烷氧化微孔催化剂的研究进展

环己烷氧化是化工生产中的重要反应之一,其氧化产物为重要的化工生产中间体,因此开发高效的环己烷氧化多相催化剂体系具有重要的理论意义和应用前景。本文综述了国内外环己烷选择氧化微孔催化剂的研究进展,分别对Y沸石、ZSM-5沸石及MOFs三大类微孔催化剂体系的组成及催化性能进行了介绍,最后展望了环己烷多相催化体系的发展趋势。     

温和条件下环己烷的均相催化氧化

温和条件下环己烷的均相催化氧化吴泽彪，张铭俊，奚祖威（中国科学院大连化学物理研究所，大连１１６０２３）关键词环己烷，氧化，均相催化．１．前言饱和烃的氧化是很多化学家都感兴趣的一个前沿性课题．强共价Ｃ─Ｈ键由于键能大，若进行剧烈氧化则产物选择性较差，氧...     

花生油存在下胆固醇氧化产物研究

探讨了温度、加热时间、花生油的量对胆固溶氧化的影响情况。用毛细管气相色谱法检出6种胆固溶氧化物。在一定范围内，氧化产物的组成和含量随加热温度升高和加热时间延长明显增加，而随着花生油量增加有明显减小的趋势。     

涂层阳极电氧化合成环氧环己烷

用廉价的涂层电极作为阳极，在Ｈ２Ｏ－ＮａＢｒ－ＭｅＣＮ（ＭｅＣＮ：Ｈ２Ｏ＝１：４）介质中，电流密度控制在０．４Ａ／ｄｍ＾２左右，由环己烯电化学氧化合成环氧环己烷，产率８２．６％。     

配位负载金属卟啉的合成及催化氧化环己烷的性能研究

合成了三种与咪唑配体键合的新型载体，并通过其与四苯基卟啉铁卟啉锰配位得到了改性的负载金属卟啉催化剂。讨论了它们在催化氧化环己烷反应中的稳定性，活性等，结果表明本位负载方式明显提高了金属卟啉的稳定性，其中硅胶配置负载锰卟啉还具有较高的活性。     

一步法绿色氧化环己烷制备己二酸的研究进展

己二酸具有巨大的工业用途及需求,然而传统的制备方法存在着高能耗、高污染等缺点,开发更加清洁绿色的制备方法是大势所趋。本文主要介绍了国内外以绿色清洁氧化剂如O2(空气)、H2O2、O3氧化环己烷一步制备己二酸的研究进展。     

Oxovanadium(IV) and copper(II) complexes of 1,2-diaminocyclohexane based ligand encapsulated in zeolite-Y for the catalytic oxidation of styrene, cyclohexene and cyclohexane

N,N′-Bis(salicylidene)cyclohexane-1,2-diamine (H₂sal-dach) reacts with oxovanadium(IV) and copper(II) exchanged zeolite-Y in refluxing methanol to yield the corresponding zeolite-Y encapsulated metal complexes, abbreviated herein as [VO(sal-dach)]-Y and [Cu(sal-dach)]-Y. Spectroscopic studies (IR, electronic and ¹H NMR), thermal analysis, scanning electron micrographs (SEM) and X-ray diffraction patterns have been used to characterise these complexes. These encapsulated complexes catalyse the oxidation, by H₂O₂, of styrene, cyclohexene and cyclohexane efficiently in good yield. Under the optimized conditions, the oxidation of styrene catalysed by [VO(sal-dach)]-Y and [Cu(sal-dach)]-Y gave 94.6 and 21.7% conversion, respectively, where styreneoxide, benzaldehyde, benzoic acid, 1-phenylethane-1,2-diol and phenylacetaldehyde being the major products. Oxidation of cyclohexene catalysed by these complexes gave cyclohexeneoxide, 2-cyclohexene-1-ol, cyclohexane-1,2-diol and 2-cyclohexene-1-one as major products. Conversion of cyclohexene achieved was 86.6% with [VO(sal-dach)]-Y and 18.1% with [Cu(sal-dach)]-Y. A maximum of 78.1% conversion of cyclohexane catalysed by [Cu(sal-dach)]-Y and only 21.0% conversion by [VO(sal-dach)]-Y with major reaction products of cyclohexanone, cyclohexanol and cyclohexane-1,2-diol have been obtained.     

Catalytic oxidation of cyclohexane over Cu-Zn-Cr ternary spinel systems

Spinel systems with the composition of Cu_1−xZn_xCr₂O₄ [x = 0 CCr, x = 0.25 CZCr-1, x = 0.5 CZCr-2, x = 0.75 CZCr-3 and x = 1 ZCr] were prepared by homogeneous co-precipitation method and were characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. Elemental analysis was done by EDX, and surface area measurements by the BET method. The redox behavior of these catalysts in cyclohexane oxidation at 243 K using TBHP as oxidant was examined. Cyclohexanone was the major product over all catalysts with some cyclohexanol. 69.2% selectivity to cyclohexanol and cyclohexanone at 23% conversion of cyclohexane was realized over zinc chromite spinels in 10 h.     

Gas chromatography in qualitative analysis Part 16. An investigation of the oxidation of reference stationary phases used in column characterization by the Rohrschneider and McReynolds methods

Summary The on-column oxidation of hydrocarbons commonly used as stationary phases in column characterization is investigated. In each case significant shifts of retention are observed, which may be negative or positive depending upon the polarity of the test solutes and the adsorptivity of the support material. In order to reduce the consequent uncertainties in the Rohrschneider [1] and McReynolds [2] polarity values, a new method of column characterization is proposed. The applicability of the new method is illustrated by a consideration of a range of silicone liquid phases.     

Gas chromatography in qualitative analyses. An investigation of the oxidation of some silicones used as gas chromatographic stationary phases

Summary The on-column oxidation of apolar and polar silicones used as gas chromatographic stationary phases is investigated. Even at 225° the effects of oxidation are found to be slight. Of the materials investigated the methylphenylsilicones are the most stable.     

GC-MS analytical methods for the determination of personal-care products in water matrices

This article discusses the more recent methods combining gas chromatography and mass spectrometry (GC-MS) for analysis of personal-care products (PCPs) in water matrices. We describe different procedures for sample extraction and preparation as well as different instrumental methods commonly used for these compounds. GC-MS and GC-tandem MS (GC-MS²), which are complementary to liquid chromatography combined with MS (LC-MS), allow identification and quantification of PCPs belonging to different classes with the sensitivity and the selectivity necessary for environmental monitoring. The compounds investigated include fragrances (e.g., nitro and polycyclic musks), antimicrobial compounds (e.g., triclosan), ultraviolet blockers (e.g., methylbenzylidene camphor), antioxidants and preservatives (e.g., phenols and p-hydroxybenzoic acid (parabens)) and insect repellents (e.g., N,N-diethyl-m-toluamide (DEET)). We critically review data in the literature by focusing attention on analytical methods devoted to simultaneous detection and quantification of structurally diverse pharmaceuticals and PCPs.     

Comparison of quantitative analytical methods in headspace gas chroamtography of residual solvents

Summary The aim of this work was to compare quantitative methods used for headspace gas chromatographic analysis of residual solvents in standard aqueous solutions and to apply the methods to the analysis of medicines. We found that all three quantitative methods (external standard, ESTD; internal standard, ISTD; and standard addition, ASTD) enable determination of the total amount of solute in the equilibrated system by analysis of defined volumes of headspace gas. The results showed that the ISTD method is more precise than ESTD and ASTD when there is no strong interaction between the residual solvents and the pharmaceutical base material. When, however, there is a strong polarpolar interaction between them, the ESTD and ISTD methods give worse results than the ASTD method, because the ASTD method can eliminate the matrix effect. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Assessment of uncertainty in pesticide multiresidue analytical methods: main sources and estimation

The estimation of the uncertainty associated to analytical methods is necessary in order to establish the comparability of results. Multiresidue analytical methods lack very often of information about uncertainty of results with likely implications when results are compared with maximum residue levels (MRL) established by regulations. An adequate identification and estimation of each uncertainty source allows to laboratories to establish the accuracy of results and to balance with time-consuming and costs.     

Recent trends in analytical methods and separation techniques for drugs of abuse in hair

Hair analysis of drugs of abuse has been a subject of growing interest from a clinical, social and forensic perspective for years because of the broad time detection window after intake in comparison to urine and blood analysis. Over the last few years, hair analysis has gained increasing attention and recognition for the retrospective investigation of drug abuse in a wide variety of contexts, shown by the large number of applications developed. This review aims to provide an overview of the state of the art and the latest trends used in the literature from 2005 to the present in the analysis of drugs of abuse in hair, with a special focus on separation analytical techniques and their hyphenation with mass spectrometry detection. The most recently introduced sample preparation techniques are also addressed in this paper. The main strengths and weaknesses of all of these approaches are critically discussed by means of relevant applications.     

Manganese(II) β-diketonate catalyzed oxidation of cyclohexane bytert-butyl hydroperoxide

Oxidation of cyclohexane bytert-butyl hydroperoxide was carried out in acetonitrile solution at room temperature in the presence of manganese(II) β-diketonate complexes, Mn(acac)₂, Mn(acac)₂.2H₂O, Mn(ba)₂.H₂O, Mn(dbm)₂ and Mn(dbm)₂.2H₂O (where acacH=acetylacetone, baH=benzoylacetone and dbmH=dibenzoyl-methane). Cyclohexanol and cyclohexanone were obtained as the products. Oxidation ofcis-cyclooctene gave the corresponding epoxide together with two minor byproducts in the presence of Mn(acac)₂.2H₂O and Mn(dbm)₂.2H₂O. A mechanistic pathway predominantly involving autoxidation is proposed. IPCL communication No. 322     

Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades

Pesticides are widely used in agriculture and can be transferred to animals in a number of ways. Consequently, reliable analytical methods are required to determine pesticide residues in foods of animal origin. The present review covers published methods and research articles (1990-2010) in which pesticide residues have been extracted from meat and meat products, milk and dairy products, fish and seafood, and eggs, then cleaned up, and isolated by chromatographic techniques to be identified and quantified by various detection methods. Recovery rates, quantification limits, the matrix effect and related parameters have all been considered. Lastly, future developments in this field are outlined.