液相微萃取技术的研究进展

液相微萃取是近年来发展起来的一种新型的样品前处理技术,该技术集采样、萃取和浓缩于一体,需要有机溶剂量非常少,是一种环境友好的萃取技术,在国内尚未广泛应用。本文综述了液相微萃取的方式、原理、影响因素和应用,引用文献30篇。     

Application of carbon nanotubes in extraction and chromatographic analysis: A review

Carbon nanotube (CNT), a well-known carbon-based nanomaterial has drawn much attention in many application fields including chemistry in the last few decades. Many researchers and scientists have shown huge interest to improve the extraction methodologies and adopt their applications in combination with chromatography technique. With respect to this, the exceptional applications of CNTs have been introduced as extraction sorbent due to their excellent inborn physical and chemical properties. In particular, CNTs have consistently been used as adsorbents in various techniques including solid-phase micro-extraction, solid-phase extraction, micro dispersive slid phase extraction, magnetic dispersive solid phase extraction, analytes enrichment, sample fractionation and clean-up as well as support for many derivatization reactions. Many research papers have discussed the successful use of CNTs to overcome the limitations of the extraction techniques due to their excellent sorbent capacity. In addition, considering the clear need to make chromatographic technique more successful, the applications of CNTs have been reported in the literatures in details as stationary and pseudo-stationary phases for the separation and extraction of challenging compounds. Because of the higher thermal and chemical stability, CNTs have been anticipated as stationary phase modifier for chromatographic applications to avoid bleeding of the columns and enable the analysis even at very high temperature (1200 °C). In liquid chromatography CNTs have primarily been used in combination with other packing materials (silica) and sometimes incorporated in a porous polymeric monolith. Therefore, the recent utilizations of CNTs as extraction materials and stationary phases have been illustrated in the current review and a table listing the details applications of CNTs in aforementioned field is provided as well. We believe that the review will help researcher to gain vast knowledge about application of carbon nanotubes in the field of separation chemistry.     

Application of ultrasound-assisted extraction to the determination of contaminants in food and soil samples

The application of ultrasound-assisted extraction (UAE) to the sample preparation of environmental and food samples has increased in the last years. This technique has been used in the development of methods for the analysis of numerous contaminants, including organic compounds (pesticides, pharmaceuticals, polycyclic aromatic hydrocarbons, polyhalogenated flame retardants, etc.) and heavy metals. The aim of this work is to review the application of this extraction procedure to the analysis of contaminants in food and soil and the comparison of its use with other well-established extraction procedures. The advantages and disadvantages of this technique together with the possibility of coupling UAE with other analytical techniques will be also discussed.     

Extraction of nonferrous metals by bisacylated diethylenetriamine

Bisacylated diethylenetriamine (BAD) with an α,α′ branched substituent has been synthesized. Conditions for the extraction of copper(II), cobalt(II), nickel(II), zinc(II), and iron(III) chlorides from hydrochloric, chloride, and ammoniac solutions have been studied. The protonation constants of the extractant and the concentration constants of metal extraction have been calculated. The extraction in the pH range of 2–10 has a coordination mechanism; at hither acidities, the extraction occurs via ion exchange.     

超临界CO2络合萃取金属离子的研究与应用

本文综述了国内外对超临界CO2络合萃取技术的研究与应用现状.总结并分析了超临界CO2流体萃取金属离子的原理、方法,动力学机理,络合剂和改性剂的选择,络合萃取过程的影响因素,并着重介绍了其在环境保护、核工业、冶金工业、化学分析、中药产业、保健品工业中的应用.最后指出了它目前存在的问题,并对未来研究方向进行了展望.     

Application of pyridylazo and thiazolylazo reagents in flow injection preconcentration systems for determination of metals

Pyridylazo and thiazolylazo reagents are synthetic dyes widely used in analytical chemistry. These reagents are also very attractive for use in preconcentration systems. This paper covers the application of pyridylazo and thiazolylazo reagents in flow injection systems for the determination of metals. The article discusses flow injection preconcentration systems with solid-phase extraction, precipitation and cloud point extraction. The use of pyridylazo and thiazolylazo reagents in flow injection detection systems is also presented. The relative advantages and drawbacks of these systems are discussed. The application of pyridylazo and thiazolylazo reagents in new systems is presented in the concluding part of this review article.     

Molecularly Imprinted Polymers for Solid Phase Extraction

The combination of molecularly imprinted polymers (MIPs) and solid phase extraction (SPE) is reviewed. MIPs, which have high selectivity and affinity for a predetermined molecule (template), have been used as sorbents for SPE to selectively isolate analytes from biological, pharmaceutical, and environmental samples. Solid phase extraction with molecularly imprinted polymers (MIP–SPE) is a promising technique which allows specific analytes to be selectively extracted from complex matrices. This survey summarizes the characteristics, development and application of MIP–SPE in recent years. Existed problems and the future direction of MIP–SPE are also discussed.     

Determination of admixtures of high-melting metals in rare-earth metals and their compounds

The study considers the possibility of using inductively coupled plasma mass spectrometry (ICP MS) for the determination of admixtures of Zr, Nb, Mo, Hf, Ta, W, and Te in rare-earth metals and their compounds using preliminary extraction or extraction-chromatographic preconcentration. The admixture elements have been separated by extraction with trioctylphosphine oxide in dichloroethane from hydrochloric acid media and back extraction with oxalic acid. Chemical separation provided a 1–4-order reduction of the lower quantification limit for these elements using ICP MS.     

Substoichiometric separation and determination of trace metals

Substoichiometric methods are eminently suitable for the determination of many elements. As a new application of substoichiometry, a substoichiometric speciation of the element in different chemical states is proposed. Substoichiometric speciation of As(III) and As(V) is demonstrated as an example. This is based on a highly selective substoichiometric extraction of As(III) with thionalide and As(V) with tetraphenylarsonium chloride in the presence of an excess amount of pyrogallol. Coexistence of other diverse arsenic species including methylarsenic compounds does not give any interference to the selective determination of As(III) and As(V). For substoichiometric radioactivation, a novel application of the synergistic extraction system in a combination of a substoichiometric amount of thenoyltrifluoroacetone with an excess amount of phenanthroline is demonstrated for Yb as an example. Substoichiometric speciation based on the selective speration and an application of synergistic extraction to substoichiometric separation have additional possibilities in substoichiometry.     

Extraction of some transition metals with N,N-dibutyl-N'-benzoylthiourea into molten paraffin at 65 degrees C

The solid-liquid extraction behaviour of some transition metals (Cu(II), Co(II), Ni(II), Cd(II) and Pb(II)) by the use of N,N-dibutyl-N'-benzoylthiourea as an extractant in paraffin (58-60 degrees C) has been investigated at 65.0+/-0.5 degrees C. The effect of equilibration time, pH of the aqueous phase, concentration of extractant and solid solvent used on the extraction efficiency of these metals have been discussed. The interferences of various ions are examined. The method has been applied to the determination of these metals in synthetic samples, mushrooms and sediment.     

蛋白质分子印迹

分子印迹技术是一种新型的高效分离技术，具有空间选择性识别特性。本文介绍了分子印迹技术在蛋白质大分子上的应用和发展，包括蛋白质分子印迹选用的单体和交联剂、印迹方法、印迹机理、蛋白质分子印迹技术的应用以及存在的一些问题。     

Importance of weak interactions in the formulation of organic phases for efficient liquid/liquid extraction of metals

Recent experimental studies demonstrate the need to take into account weak interactions in the understanding of solvent extraction processes. This well-established industrial technology now beneficiates of a supramolecular approach, complementary to the traditional analysis based on coordination chemistry. In this article, we focus on the integration of a colloidal approach in the analysis of solvent extraction systems: organic phases used are complex fluids, in which extracting molecules self-assemble into reverse aggregates. We detail the available analytical tools used towards characterization of these organic phases and emphasize the recent results in aggregation-driven extraction. All experimental data are discussed in light of theoretical approaches which propose adequate thermodynamic models and shed light on the importance of entropy on the phenomena. Diluent effects and synergism have been successfully rationalized, efficient new formulations based on a physicochemical analysis have been proposed and the door is now open for further development at industrial scale.     

离子液体和聚离子液体固相微萃取涂层制备及应用进展

固相微萃取(Solid-phase microextraction,SPME)技术因其具有操作简单、萃取时间短、无需有机溶剂、易于自动化操作等优点,成为近年来发展起来的一种新型样品前处理技术。涂层是SPME技术的核心,决定了涂层萃取的选择性和容量。离子液体和聚离子液体因具有环境友好、蒸汽压低、热稳定性好、设计灵活、粘度大等特点,已作为一类新的涂层材料广泛应用于SPME,并对各种分析物均展现出良好的萃取效果和选择性。本文从制备技术、形貌、选择性、稳定性、寿命、应用等方面综述了近年来离子液体和聚离子液体基SPME涂层的研究进展,对它们的优缺点进行了对比讨论,并对其未来发展方向进行了展望。     

Neutron activation determination of noble metals for the analysis of technological and natural materials

Two previously developed methods of noble metal neutron activation (NA) determination have been applied for the analysis of technological materials. While comparing the data obtained by both methods with those obtained in Central Chemical Laboratory the systematical discreapences have been shown to be absent. A new method of Pd, Au, Pt and Ir NA determination in natural and technological specimens based on the selective extraction of Pd and Au preliminary to irradiation has been developed. Results of the analysis of “Glomar Cellenger”'s deep-water drilling samples are discussed obtained by this method.     

Kinetic studies on the solvent extraction of uranium (IV), thorium (IV) and uranium (VI) from nitric acid solutions with tributyl phosphate

The kinetics of solvent extraction of U (IV), Th (IV) and U (VI) from nitric acid solution with tributyl phosphate (TBP) in kerosene and cyclohexane have been studied using the single drop technique. The effects of concentrations of U (IV), Th (IV), U (VI), nitric acid, nitrate, TBP and temperature on the extraction rates of U (IV), Th (IV) and U (VI) have been examined. The mechanisms for the three extraction processes are discussed.     

Microanalytical flow-through method for assessment of the bioavailability of toxic metals in environmental samples

The application of a recently proposed microanalytical flow-through system for on-line sequential extraction of heavy metals from solid samples of environmental interest is described. Using various extraction schemes (a nitric acid scheme, a two-stage extraction scheme using two reagents applied in the BCR procedure) and comparison with the common batch sequential BCR procedure, the suitability of the system for fast screening of solid environmental samples is demonstrated. By pumping leaching agents sequentially through the sample held in a micro cartridge, the different metal fractions present can be assessed in less than an hour. Method evaluation was performed using SRM 1648 urban particulate matter and BCR 701 lake sediment reference material certified for extractable metals. The need for and design of laboratory internal reference material suitable for simulating the natural (dynamic) processes of metal release into the environment is also discussed. For the first time correlation is sought between fractionation techniques and physiologically based methods for assessment of the bioaccessibility of metals in biomatrices.     

Neutron activation method in the analysis of geological materials for noble metals

The paper is concerned with various applications of the neutron activation method in the analysis of geological samples for noble metals. A technique is suggested to estimate a priori detection limit values for noble metals in the nondestructive analysis of various samples. Also discussed are new schemes of separation and isolation of elements, the technique of obtaining comparison standards, and constraining factors in application of the method in terms of representation of samples to be analyzed.     

Separation and preconcentration by a cloud point extraction procedure for determination of metals: an overview

Recently, cloud point extraction (CPE) has been an attractive subject as an alternative to liquid–liquid extraction. The technique is based on the property of most non-ionic surfactants in aqueous solutions to form micelles and become turbid when heated to the cloud point temperature. This review covers a selection of the literature published on applications of CPE in determination of metal ions over the period between 2004 and 2008.     

Solvent extraction of metals with commercial oxime extractant (LIX 622)

The extraction characteristics of some selected metals from an aqueous buffered solution by LIX 622, a commercial oxime extractant have been studied. The pH_1/2 values for extracting different metals with 5 v/v% LIX 622 extractant in methyl isobutyl ketone (MIBK) have been obtained. The order of extraction of metals with LIX 622 extractant as a function of pH_1/2 value is determined and results agree well with the order obtained using salicylaldoxime as chelating ligand for the extraction of these metals.     

微波萃取法研究进展

对近几年微波萃取法的研究进展及其应用进行了综述。具体介绍了微波萃取的原理、特点、萃取参数及其在环境、生化、食品、化工分析和天然产物提取等领域的应用,并从简化样品预处理步骤、开发微波萃取新技术、探讨萃取机理和改进仪器装置４个方面展望了该法的发展前景,引用文献４６篇