Recent advances of online coupling of sample preparation techniques with ultra high performance liquid chromatography and supercritical fluid chromatography

Ultra high performance liquid chromatography and supercritical fluid chromatography techniques are favored because of their high efficiency and fast analysis speed. Although many sample preparation techniques have been coupled with common liquid chromatography online, the online coupling of sample preparation with the two popular chromatography techniques have gained increasing attention owing to the increasing requirements of efficiency and sensitivity. In this review, we have discussed and summarized the recent advances of the online coupling of sample preparation with ultra high performance liquid chromatography and supercritical fluid chromatography techniques. The main sample preparation techniques that have been coupled with ultra high performance liquid chromatography online are solid‐phase extraction and in‐tube solid‐phase microextraction, while solid‐phase extraction and supercritical fluid extraction are the main techniques that have been coupled with supercritical fluid chromatography online. Especially, the strategies for online coupling of sample preparation with chromatography techniques were summarized. Typical applications and growing trends of the online coupling techniques were also discussed in detail. With the increasing demands of improving the efficiency, throughput, and analytical capability toward complex samples of the analysis methods, online coupling of sample preparation with chromatography techniques will acquire further development.     

Ultrasound: A subexploited tool for sample preparation in metabolomics

Metabolomics, one of the most recently emerged “omics”, has taken advantage of ultrasound (US) to improve sample preparation (SP) steps. The metabolomics–US assisted SP step binomial has experienced a dissimilar development that has depended on the area (vegetal or animal) and the SP step. Thus, vegetal metabolomics and US assisted leaching has received the greater attention (encompassing subdisciplines such as metallomics, xenometabolomics and, mainly, lipidomics), but also liquid–liquid extraction and (bio)chemical reactions in metabolomics have taken advantage of US energy. Also clinical and animal samples have benefited from US assisted SP in metabolomics studies but in a lesser extension. The main effects of US have been shortening of the time required for the given step, and/or increase of its efficiency or availability for automation; nevertheless, attention paid to potential degradation caused by US has been scant or nil. Achievements and weak points of the metabolomics–US assisted SP step binomial are discussed and possible solutions to the present shortcomings are exposed.     

State of the art of environmentally friendly sample preparation approaches for determination of PBDEs and metabolites in environmental and biological samples: A critical review

Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003–2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed.     

基于色谱-质谱联用的脂质分析样品前处理技术研究进展

脂质作为细胞膜和亚细胞膜的主要结构成分,在能量来源、细胞信号传导等多种生物学过程中发挥着重要作用。近年来,脂质分析受到越来越多的关注,其中色谱-质谱联用技术在脂质分析中占据主导地位。由于样品基质复杂,样品前处理有富集痕量物质和减少基质干扰的作用,成为脂质分析中的一个关键步骤。该文综述了近年来基于色谱-质谱联用技术的脂质分析中样品前处理技术的研究进展和应用,对各种样品前处理技术进行了阐述和总结。基于液相的萃取方法有液-液萃取和单一有机溶剂萃取。基于固相的萃取方法包括固相萃取和固相微萃取。场辅助萃取方法包括超临界流体萃取、加压流体萃取、微波辅助萃取和超声辅助萃取。此外,还介绍了在线联用样品前处理方法和用于活体分析的样品前处理方法。最后,对基于色谱-质谱联用的脂质分析样品前处理技术存在的问题及发展趋势进行了探讨。样品前处理技术的发展将提高脂质分析的灵敏度、选择性和分析速度。     

Electrical field-induced extraction and separation techniques: Promising trends in analytical chemistry – A review

Sample preparation is an important issue in analytical chemistry, and is often a bottleneck in chemical analysis. So, the major incentive for the recent research has been to attain faster, simpler, less expensive, and more environmentally friendly sample preparation methods. The use of auxiliary energies, such as heat, ultrasound, and microwave, is one of the strategies that have been employed in sample preparation to reach the above purposes. Application of electrical driving force is the current state-of-the-art, which presents new possibilities for simplifying and shortening the sample preparation process as well as enhancing its selectivity. The electrical driving force has scarcely been utilized in comparison with other auxiliary energies. In this review, the different roles of electrical driving force (as a powerful auxiliary energy) in various extraction techniques, including liquid-, solid-, and membrane-based methods, have been taken into consideration. Also, the references have been made available, relevant to the developments in separation techniques and Lab-on-a-Chip (LOC) systems. All aspects of electrical driving force in extraction and separation methods are too specific to be treated in this contribution. However, the main aim of this review is to provide a brief knowledge about the different fields of analytical chemistry, with an emphasis on the latest efforts put into the electrically assisted membrane-based sample preparation systems. The advantages and disadvantages of these approaches as well as the new achievements in these areas have been discussed, which might be helpful for further progress in the future.     

Comparison of extraction techniques of robenidine from poultry feed samples

In this paper, effectiveness of six different commonly applied extraction techniques for the determination of robenidine in poultry feed has been compared. The sample preparation techniques included shaking, Soxhlet, Soxtec, ultrasonically assisted extraction, microwave – assisted extraction and accelerated solvent extraction. Comparison of these techniques was done with respect to the recovery extraction, temperature and time, reproducibility and solvent consumption. Every single extract was subjected to clean – up using aluminium oxide column (Pasteur pipette filled with 1 g of aluminium oxide), from which robenidine was eluted with 10 ml of methanol. The eluate from the clean-up column was collected in a volumetric flask, and finally it was analysed by HPLC–DAD–MS. In general, all extraction techniques were capable of isolating of robenidine from poultry feed, but the recovery obtained using modern extraction techniques was higher than that obtained using conventional techniques.

In particular, accelerated solvent extraction was more superior to other techniques, which highlights the advantages of this sample preparation technique. However, in routine analysis, shaking and ultrasonically assisted extraction is still the preferred method for the solution of robenidine and other coccidiostatics.     

Analysis of emerging organic contaminants in environmental solid samples

Spreading sewage sludge on agricultural lands has been actively promoted by national authorities as an economic way of recycling. However, as by-product of wastewater treatment, sewage sludge may contain toxic substances, which could be incorporated into agricultural products or be distributed in the environment. Moreover, sediments can be contaminated by the discharge of wastewater effluents into rivers. This article reviews the determination of emerging contaminants (surfactants, flame retardants, pharmaceuticals and personal care products) in environmental solid samples (sludge, soil and sediment). Sample preparation, including extraction and clean-up, as well as the subsequent instrumental determination of contaminants are discussed. Recent applications of extraction techniques, such as Soxhlet extraction, ultrasound assisted extraction, pressurised liquid extraction, microwave assisted extraction and matrix solid-phase dispersion to the analysis of emerging contaminants in environmental solid samples are reviewed. Determination of these contaminants, generally carried out by gas chromatography and liquid chromatography coupled with different detectors, especially mass spectrometry for the identification and quantification of residues, is also summarised and discussed.      

水产品中有害物质分析样品前处理技术研究进展

水产品含有丰富的蛋白、维生素和多种微量元素,是人们摄取动物性蛋白质的重要来源之一,我国是世界上最大的水产品消费国,其质量安全问题一直备受关注。但水产样品基质复杂,有害物质的含量低,须对其进行分离富集后才能进行检测,传统的液-液萃取、固相萃取和快速固相分散萃取等样品前处理技术在水产品分析中得到广泛应用,同时针对一些挥发性和超痕量有害物质检测时,固相微萃取同样体现出巨大优势。这些样品前处理技术可以有效去除基体对分析对象的干扰,提高检测方法的灵敏度和准确度。根据目标分析物性质的不同,选择合适的样品前处理技术,是水产品中有害物质分析的关键步骤。该文以水产品中有害物的来源不同,将其分为3类:(1)水产品中环境污染物的分析;(2)养殖运输和加工过程中有害物的分析;(3)水产品中生物毒素的分析。以这3类有害物质的分析为主线,综述了近10年水产品中有害物质分析的样品前处理技术,包括液-液萃取、固相萃取、固相微萃取、快速固相分散萃取和磁性固相萃取等。此外,还对各种技术的优缺点进行了探讨,并对其未来发展方向进行了展望。     

新型样品前处理材料在环境污染物分析检测中的研究进展

针对复杂样品的分析和痕量目标物的检测,样品前处理是必不可少的,高效的样品前处理技术不仅可以去除或减小样品基质干扰而且能够实现分析物的富集,提高分析检测的准确性和灵敏度.近年来,固相萃取、磁分散固相萃取、枪头固相萃取、搅拌棒萃取、固相微萃取等高效的样品前处理技术已在环境污染物分析检测中获得广泛关注,萃取效率主要取决于萃取...     

Sample handling strategies for the determination of persistent trace organic contaminants from biota samples

Even after emergence of most advanced instrumental techniques for the final separation, detection, identification and determination of analytes, sample handling continues to play a basic role in environmental analysis of complex matrices. In fact, sample preparation steps are often the bottleneck for combined time and efficiency in many overall analytical procedures. Thus, it is not surprising that, in the last two decades, a lot of effort has been devoted to the development of faster, safer, and more environment friendly techniques for sample extraction and extract clean up, prior to actual instrumental analysis. This article focuses on the state of the art in sample preparation of environmental solid biological samples dedicated to persistent organic pollutants (POPs) analysis. Extraction techniques such as Soxhlet extraction, sonication-assisted extraction, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), pressurised liquid extraction (PLE) and matrix solid-phase dispersion (MSPD) are reviewed and their most recent applications to the determination of POPs in biota samples are provided. Additionally, classical as well as promising novel extraction/clean-up techniques such as solid phase microextraction (SPME) are also summarized. Finally, emerging trends in sample preparation able to integrate analytes extraction and their adequate clean-up are presented.     

Evolution of dispersive liquid–liquid microextraction method

Dispersive liquid–liquid microextraction (DLLME) has become a very popular environmentally benign sample-preparation technique, because it is fast, inexpensive, easy to operate with a high enrichment factor and consumes low volume of organic solvent. DLLME is a modified solvent extraction method in which acceptor-to-donor phase ratio is greatly reduced compared with other methods. In this review, in order to encourage further development of DLLME, its combination with different analytical techniques such as gas chromatography (GC), high-performance liquid chromatography (HPLC), inductively coupled plasma-optical emission spectrometry (ICP-OES) and electrothermal atomic absorption spectrometry (ET AAS) will be discussed. Also, its applications in conjunction with different extraction techniques such as solid-phase extraction (SPE), solidification of floating organic drop (SFO) and supercritical fluid extraction (SFE) are summarized. This review focuses on the extra steps in sample preparation for application of DLLME in different matrixes such as food, biological fluids and solid samples. Further, the recent developments in DLLME are presented. DLLME does have some limitations, which will also be discussed in detail. Finally, an outlook on the future of the technique will be given.     

样品前处理-色谱分析在线联用技术的研究进展

样品前处理是色谱分析中耗时最多、最容易引起误差的关键环节,因此有关样品前处理技术与色谱分析的在线联用的研究已成为分析化学的前沿课题。本文综述了近年来各种样品前处理技术与色谱分析在线联用的研究进展,包括固相萃取、固相微萃取与液相微萃取、膜辅助萃取、场作用辅助萃取、气相萃取、热解吸以及微芯片分离技术。     

Advances in sample preparation in chromatography for organic environmental pollutants analyses

Many pollutants are present at trace level in our environment, which are beyond the scope of the detection by advance instruments too. Therefore, there is urgent need to develop advance sample preparation methods to determine the concentrations of the pollutants even at trace levels. Keeping this into consideration, many extraction techniques have been developed and applied for the analysis of organic pollutants in environmental samples. This review presents the sate-of-the-art of sample preparation methods in environmental samples. The extraction techniques discussed are headspace, liquid based extraction, supported liquid, homogeneous liquid–liquid, homogeneous liquid–liquid, single drop micro-extraction, membrane assisted solvent, solid-phase, molecularly imprinted solid-phase, monolithic spin column, matrix solid-phase, dispersive solid-phase, disposable pipette, magnetic solid-phase, solid-phase micro-extraction, micro-extraction by packed sorbent and stir bar sorptive. The article will be highly useful for environmental chromatographers.     

磁性纳米材料在样品前处理中的应用进展与展望

在样品前处理技术中,吸附剂材料起关键作用。随着纳米材料的发展,越来越多的纳米材料被用作吸附剂以提高对目标物的萃取效率。磁性纳米材料因其具有易于分离、表面可修饰、吸附能力强和良好的生物相容性等优异性能,已广泛应用于分析方法的样品前处理技术中。该文通过对磁性纳米材料在磁性固相萃取和在其他样品前处理技术中的研究与应用展开总结和论述,对磁性纳米材料的稳定性、作用力、比表面积及孔径调控的制备进行了阐述,展望了磁性纳米材料在分离科学中的应用前景,为进一步研究磁性纳米材料的应用提供了参考。     

Electromembrane extraction from biological fluids

Electro-assisted extraction of ionic drugs from biological fluids through a supported liquid membrane (SLM) and into an aqueous acceptor solution was recently introduced as a new sample preparation technique termed electromembrane extraction (EME). The applied electrical potential across the SLM has typically been in the range of 1-300 V. Successful extractions have been demonstrated even with common batteries (9 V) instead of a power supply. The chemical composition of the SLM has been crucial for the selectivity and for the recoveries of the extraction. Compared to other liquid-phase microextraction techniques (LPME), extraction times have been reduced by a factor of 6-17, and successful extractions have been obtained at extraction times of 1-5 min, and even down to a few seconds with online microfluidic EME devices. The technique has provided very efficient sample clean-up and has been found well suited for the extraction of sample sizes in the low μL range. Extractions have been performed with both rod-shaped hydrophobic porous fibers and with flat hydrophobic porous sheets as SLM support. The technique has been successfully downscaled into the micro-chip format. The nature of the SLM has been tuned for extraction of drugs with different polarity allowing extractions to be tailored for specific applications depending on the analyte of interest. The technique has been found to be compatible with a wide range of biological fluids and extraction of drugs directly from untreated human plasma and whole blood has been demonstrated. EME selectively extracts the compounds from the complex biological sample matrix as well as allowing concentration of the drugs. With home-built equipment fully acceptable validation results have been obtained.     

Monolith as a new sample preparation material: recent devices and applications

Monolith was first used as a material for chromatographic separation two decades ago and solid-phase extraction over 10 years, and since then, separation science has undergone a dramatic change owing to advancements in analytical technology. Recently, monolith has been modified to suit various devices for the extraction and enrichment of analytes in any matrices of environmental, food, and biological analyses. This approach has contributed to miniaturization and automation for sample preparation, and it can reduce the time and cost requirements of sample preparation. Recently, numerous applications have been demonstrated for online and inline preconcentration coupled with monolith, and many kinds of devices have been designed and developed for offline devices. In this review, these applications and devices are listed and discussed in reference to other fields.     

The role of graphene‐based sorbents in modern sample preparation techniques

The application of graphene‐based sorbents in sample preparation techniques has increased significantly since 2011. These materials have good physicochemical properties to be used as sorbent and have shown excellent results in different sample preparation techniques. Graphene and its precursor graphene oxide have been considered to be good candidates to improve the extraction and concentration of different classes of target compounds (e.g., parabens, polycyclic aromatic hydrocarbon, pyrethroids, triazines, and so on) present in complex matrices. Its applications have been employed during the analysis of different matrices (e.g., environmental, biological and food). In this review, we highlight the most important characteristics of graphene‐based material, their properties, synthesis routes, and the most important applications in both off‐line and on‐line sample preparation techniques. The discussion of the off‐line approaches includes methods derived from conventional solid‐phase extraction focusing on the miniaturized magnetic and dispersive modes. The modes of microextraction techniques called stir bar sorptive extraction, solid phase microextraction, and microextraction by packed sorbent are discussed. The on‐line approaches focus on the use of graphene‐based material mainly in on‐line solid phase extraction, its variation called in‐tube solid‐phase microextraction, and on‐line microdialysis systems.     

样品前处理技术在气相色谱分析中的应用进展

气相色谱法是当前应用最广泛的分析技术之一。使用气相色谱对复杂基体进行分析时的样品前处理步骤往往繁琐耗时,易引起误差,已成为制约分析效率和准确度提升的关键环节。本文综述了2009-2013年几种主要的样品前处理技术,包括吹扫捕集、固相萃取、固相微萃取、液相微萃取技术以及微波辅助萃取、超声波辅助萃取等场辅助萃取技术在气相色谱分析中的应用研究进展。     

基于电驱动在线快速分离富集技术的研究进展

样品前处理能将待测物从复杂基质中预先分离富集出来,以提高分析方法的灵敏度、选择性和准确性,是复杂样品分析的关键步骤。样品前处理是一个非自发的、从无序到有序的熵减过程,不仅费时费力,还极易引起误差。向体系输入能量和降低体系熵值可以增强分离富集效果,加快样品制备过程。将电场引入在线样品前处理,既能向体系做功,又能驱动样品定向迁移,使前处理的熵减过程快速顺利进行,是快速样品制备的有效途径。基于电驱动的在线分离富集技术综合了多种加速策略：（1）以电场形式向体系输入能量,加速传质和传热过程;（2）采用电渗流、电泳等电驱动定向流实现样品在分离、富集、检测各步骤之间的定向迁移,保证样品前处理与检测顺利进行;（3）利用在线联用技术集成样品前处理与分析检测各步骤,从而提高自动化程度,减少人为误差;（4）通过微型化装置或微萃取方法提高样品制备效率,缩短样品制备时间。该文总结了近10年与基于电驱动的在线快速分离富集技术相关的90多篇文献,综述了该技术领域的研究进展,探讨了电驱动毛细管在线快速分离富集技术、电驱动芯片在线快速分离富集技术和电驱动膜萃取在线分离富集技术各自的优势和潜力,并展望了该类技术的发展与应用趋势。