分散液液微萃取技术的研究进展

分散液液微萃取是一种基于传统液液萃取的新型样品前处理技术。该文以分散液液微萃取技术中萃取剂的筛选为出发点,综述了低密度萃取剂、辅助萃取剂、反萃取剂和离子液体等低毒性萃取剂在该技术中的应用,以及应用自制装置、溶剂去乳化、悬浮萃取剂固化,辅助萃取,反萃取和离子液体-分散液液微萃取等萃取模式;并简要评述了该技术与液液萃取、固相萃取、固相微萃取、分散固相萃取、基质固相分散萃取、超临界流体萃取、超声辅助萃取等其他样品前处理技术的联用特性。     

微萃取技术在环境分析中的应用

微萃取技术是近年来出现的绿色样品前处理技术。它具有操作简便、环境友好等优点,并且在环境、医药及食品等领域得到广泛的应用。本文仅就固相微萃取和液相微萃取在环境分析中的应用作一简要综述。     

固相萃取技术在食品痕量残留和污染分析中的应用

食品痕量残留和污染分析中,样品的前处理极为重要,也是其难点所在。由于食品和农产品样品的多样性和复杂性,目前还没有一种前处理技术能够适合所有情况下的所有样品。本文对近年来发展起来的新型固相萃取技术如固相微萃取、搅拌棒吸附萃取、基质固相分散萃取、分子印迹固相萃取、免疫亲和固相萃取、整体柱固相萃取、碳纳米管固相萃取等在食品痕量残留和污染分析中的应用进行了综述,对未来的发展前景作了展望。     

固相微萃取在水样污染物检测中的应用

固相微萃取是一种具有高灵敏度、回收率和重复性等优点的前处理技术,广泛应用于水中痕量污染物的处理,本文从固相微萃取装置、基本原理及其在水样污染物检测的中应用展开介绍,并以固相微萃取作为主题检索词,利用ISI Web of Knowledge中Web of Science引文数据库,对1998年到2012年间的相关文献进行计量分析。结果表明,固相微萃取主要应用于水样前处理,杀虫剂是主要的富集对象,气相、液相色谱以及质谱是常使用的检测器。     

复杂样品的固相微萃取-直接质谱分析技术研究进展

常压离子化质谱分析技术由于具有无需样品预处理、操作简单、分析效率高等特点,现已在复杂样品的快速分析方面发挥了重要作用。但是,该技术在质谱分析时将样品基质和待测化合物同时进行电离,样品基质对目标化合物的质谱分析造成了严重干扰。为了解决这一问题,在质谱直接分析前先采用固相微萃取技术对复杂样品中的目标化合物进行富集或基质去除,可极大地提高待测化合物的质谱分析灵敏度。该文着重综述了近几年发展起来可直接与常压电离源相联用或可原位电离目标化合物的固相微萃取技术,介绍了它们的原理及在复杂样品分析领域的应用,展望了固相微萃取-直接质谱分析技术的发展趋势。     

样品制备与处理的进展——无溶剂萃取技术

本文讨论了现代分析化学的重要领域之一, 样品制备及前处理技术的进展--无溶剂萃取技术。包括气相萃取、超临界流体萃取、膜萃取、固相萃取、固相微萃取等方法。简述了这些方法的原理及其应用, 探讨了样品制备与前处理技术的发展动向。     

离子液体在微萃取技术中的应用

离子液体是在室温或近于室温下呈液态的熔盐体系,由特定阳离子和阴离子构成。与传统的液态物质相比,离子液体几乎没有蒸气压、不易挥发、能溶解许多无机物和有机物。在样品前处理技术中得到了广泛的应用。微萃取技术是一种简便快速、提取效率高、溶剂用量少、环境友好的样品前处理技术。本文综述了离子液体在微萃取技术(液相微萃取和固相微萃取)中的应用。     

固相微萃取技术在水样污染物检测中的应用

固相微萃取是一种具有高灵敏度、回收率和重复性等优点的前处理技术,广泛应用于水中痕量污染物的处理。本文从固相微萃取装置、基本原理及其在水样污染物检测的中应用展开介绍,并以固相微萃取作为主题检索词,利用ISI Web of Knowledge中Web of Science引文数据库,对1998年到2012年间的相关文献进行计量分析。检索分析结果表明,固相微萃取主要应用于水样前处理,杀虫剂和多环芳香烃是主要的富集对象,气相、液相色谱及质谱是常使用的检测仪器。     

金属检测中新型前处理技术研究进展及应用

精准检测环境和食品中金属含量对环境保护和人体健康至关重要.样品的准备环节是造成样品损失和二次污染的关键步骤, 因此合适的前处理方法可以提高金属分析的选择性和灵敏度.从液相萃取和非液相萃取新技术两方面综述了浊点萃取、离子液体、超分子溶剂-分散液液微萃取、顶空固相微萃取技术、超临界流体萃取特点及在复杂样品前处理中的应用和研究进展, 并对其未来发展方向进行了展望.     

石墨烯及其复合材料在样品前处理中的应用

样品前处理新技术与方法研究是现代分析化学的重要研究课题与发展方向之一。固相萃取是目前应用最为广泛的样品前处理技术,其技术核心是吸附材料,因此开发新型吸附材料是样品前处理领域的研究热点。石墨烯是一种新型碳纳米材料,由于其良好的物理化学性质,在短短几年内迅速成为众多学科的研究热点。其高比表面积、良好的化学稳定性和热稳定性使之在分离科学领域得到广泛的应用。本文系统综述了石墨烯及其复合材料在样品前处理中的应用研究,主要包括其作为固定相在固相萃取、固相微萃取、磁固相萃取等技术在环境、食品、生物等样品前处理中的应用。     

Hollow fiber-mediated liquid-phase microextraction of chemical warfare agents from water

Unambiguous detection and identification of chemical warfare agents (CWAs) and related compounds are of paramount importance from verification point of view of Chemical Weapons Convention (CWC). It requires development of fast, reliable, simple and reproducible sample preparation of CWAs from water which is likely to be contaminated during deliberate or inadvertent spread of CWAs. This work describes development of hollow fiber liquid-phase microextraction (HF-LPME) method for efficient extraction of CWAs (such as sarin, sulfur mustard and their analogues) from water followed by gas chromatography-mass spectrometric analysis. Extraction parameters, such as organic solvent, agitation, extraction time, and salt concentration were optimized. Best recoveries of target analytes were achieved using 1 microL trichloroethylene as extracting solvent, 1000 rpm stirring rate, 15 min extraction time, and 30% NaCl. Excellent precision was observed with less than 7.6% RSD. The limit of detection by HF-LPME was achieved up to 0.1 microg/L at 30% salt concentration.     

Determination of degradation products of chemical warfare agents in water using hollow fibre-protected liquid-phase microextraction with in-situ derivatisation followed by gas chromatography-mass spectrometry

Hollow fibre-protected liquid-phase microextraction (HF-LPME) together with gas chromatography/mass spectrometry was investigated for the analysis of degradation products of chemical warfare agents in water samples. The degradation products studied were those of nerve and blister agents, and a psychotomimetic agent. Extractions were successfully performed coupled with in-situ derivatisation using a mixture of solvent and derivatising agent. The protection of the moisture-sensitive derivatising agent was afforded by the hollow fibre. Parameters such as extraction solvent, pH, salt concentration, stirring speed and extraction time were optimised using spiked deionised water samples. The linear range established was between 0.005 and 5 microg ml(-1) depending on analyte, with squared regression coefficients ranging from 0.9929 to 1.0000. Relative standard deviations ranged from 9% to 22%. As compared to those of solid-phase microextraction, the limits of detection (0.01-0.54 microg l(-1)) of the newly-developed approach were significantly improved.     

Rapid screening of precursor and degradation products of chemical warfare agents in soil by solid-phase microextraction ion mobility spectrometry (SPME-IMS)

The use of solid-phase microextraction (SPME) coupled to ion mobility spectrometry (IMS) to detect precursor and degradation products of chemical warfare agents (CWAs) as soil contaminants was investigated. The development and characterization of a system to interface a thermal desorption solid-phase microextraction inlet with a hand held ion mobility spectrometer was demonstrated. The analytes used in this study were diisopropyl methylphosphonate (DIMP), diethyl methylphosphonate (DEMP), and dimethyl methylphosphonate (DMMP). Two SPME fibers with different stationary phases, 100 μm polydimethylsiloxane (PDMS) and 65 μm polydimethylsiloxane divinylbenzene (PDMS/DVB), were evaluated in this study to determine the optimal fiber and extraction conditions. Better results were obtained with the PDMS fiber. SPME-IMS offered good repeatability and detection of the precursor and degradation products in spiked soil at concentrations as low as 10 μg/g. Sample analysis time was less than 30 min for all the precursor and degradation products.     

Determination of trace level chemical warfare agents in water and slurry samples using hollow fibre-protected liquid-phase microextraction followed by gas chromatography-mass spectrometry

A simple and solvent-minimised sample preparation technique based on hollow fibre-protected liquid-phase microextraction was investigated for the gas chromatography/mass spectrometric analysis of chemical warfare agents in water and slurry samples. The chemical warfare agents included four nerve agents and a blister agent. Parameters such as extraction solvent, salt concentration, stirring speed and extraction time were optimised using spiked deionised water samples. The technique provided a linear range of two orders of magnitude, good repeatability (RSDs < 10%, n = 6), good linearity (r2 >or= 0.995) and limits of detection (LODs) in the range of 0.02-0.09 microg l(-1) (S/N = 3) under full scan mode. The optimised technique was also applied to more complex slurry samples and similar precision (RSD < 15%, n = 3) and limits of detection (0.02-0.2 microgl(-1), S/N = 3) were obtained.     

Trace level detection and identification of chemicals related to the chemical weapons convention from complex organic samples

A solid-phase extraction (SPE) method involving selective usage of solvents has been developed for trace level identification of chemical warfare agents (CWAs) present in a complex organic background. The total ion chromatograms obtained from direct gas chromatography-electron ionization mass spectrometric analysis of samples spiked with CWAs in the presence of diesel are very complex and dominated by hydrocarbon peaks and the same after treatment with SPE show distinct peaks corresponding to spiked chemicals. The recovery of samples from SPE is found to be 70-85% at the 10 ppm level.     

Determination of chemical warfare agents and related compounds in environmental samples by solid-phase microextraction with gas chromatography

Solid phase microextraction (SPME) is an increasingly common method of sample isolation and enhancement. SPME is a convenient and simple sample preparation technique for chromatographic analysis and a useful alternative to liquid-liquid extraction and solid phase extraction. SPME is speed and simply method, which has been widely used in environmental analysis because it is a rather safe method when dealing with highly toxic chemicals. A combination of SPME and gas chromatography (GC) permits both the qualitative and quantitative analysis of toxic industrial compounds, pesticides and chemical warfare agents (CWAs), including their degradation products, in air, water and soil samples. This work presents a combination of SPME and GC methods with various types of detectors in the analysis of CWAs and their degradation products in air, water, soil and other matrices. The combination of SPME and GC methods allows for low detection limits depending on the analyte, matrix and detection system. Commercially available fibers have been mainly used to extract CWAs in headspace analysis. However, attempts have been made to introduce new fiber coatings that are characterized by higher selectivities towards different analytes of interest. Environmental decomposition of CWAs leads to the formation of more hydrophilic products. These compounds may be isolated from samples using SPME and analyzed using GC however, they must often be derivatized first to produce good chromatography. In these cases, one must ensure that the SPME method also meets the same needs. Otherwise, it is helpful to use derivatization methods. SPME may also be used with fieldportable mass spectrometry (MS) and GC-MS instruments for chemical defense applications, including field sampling and analysis. SPME fibers can be taken into contaminated areas to directly sample air, headspaces above solutions, soils and water.     

Sorbent- and liquid-phase microextraction techniques and membrane-assisted extraction in combination with gas chromatographic analysis: A review

Approaches are described for on-line and off-line sample pretreatment of liquid samples utilising liquid- and adsorbent- and sorbent-phase microextraction methodologies with GC analysis. Solid-phase microextraction (SPME), stir-bar sorptive extraction (SBSE), on-line solid-phase extraction (SPE), liquid-phase microextraction (LPME) and membrane-assisted methods are critically evaluated and the applicability of each technique is demonstrated with examples.     

Membrane-based microextraction techniques in analytical chemistry: A review

The use of membrane-based sample preparation techniques in analytical chemistry has gained growing attention from the scientific community since the development of miniaturized sample preparation procedures in the 1990s. The use of membranes makes the microextraction procedures more stable, allowing the determination of analytes in complex and “dirty” samples. This review describes some characteristics of classical membrane-based microextraction techniques (membrane-protected solid-phase microextraction, hollow-fiber liquid-phase microextraction and hollow-fiber renewal liquid membrane) as well as some alternative configurations (thin film and electromembrane extraction) used successfully for the determination of different analytes in a large variety of matrices, some critical points regarding each technique are highlighted.     

Microporous silica with nanolayer structure coated with renewable organic solvent film as a novel extracting phase: A combination of solid- and liquid-phase microextraction

A new method based on combination of solid- and liquid-phase microextraction was developed. For the first time, porous flower-like silica microstructures with nanometric layers were created on the surface of the stainless steel wire by a new facile hydrothermal process. The fiber, coated with a suitable organic solvent, was applied for microextraction of some organophosphorus pesticides from aqueous samples followed by gas chromatography-nitrogen phosphorous detection. Method detection limits were between 0.6 and 3 ng L⁻¹. Relative standard deviations for intra- and inter-day precision were 4.4–7.3% and 5.1–7.8%, respectively. Fiber-to-fiber reproducibility for five prepared fibers was 6.3–8.4%. Tap, river and waste water samples were analyzed for evaluation of the method in real sample analysis. Relative recoveries for spiked tap, river and waste water samples were in the range of 94–101%, 89–97% and 82–103%, respectively. In addition, the method was compared with two commercial solid-phase microextraction (SPME) fibers, single drop microextraction (SDME) and liquid-phase microextraction (LPME). The present method showed higher extraction efficiency as compared with SDME, LPME and commercial SPME fibers.