亲水作用色谱及其在环境分析中的应用进展

亲水作用色谱(HILIC)是一种分离极性和亲水性化合物的液相色谱模式,其作为反相液相色谱(RPLC)的重要补充,近年来越来越受到各个领域的关注和重视。这不只是因为强极性化合物的分离问题在各个领域引起了重视,而且因为与RPLC比较,HILIC具有流动相组成黏度低、色谱柱渗透性好、与质谱联用的灵敏度高及反压较低等优势。本文简要概述了HILIC的发展历程、特点及保留机理,重点介绍了HILIC用于环境分析的最新进展,评述了HILIC及RPLC用于污染物分析的优缺点,并指出了HILIC用于环境分析的未来发展趋势。     

Hydrophilic interaction chromatography in drug analysis

Hydrophilic interaction chromatography (HILIC) is an increasingly popular alternative to conventional HPLC for drug analysis. It offers increased selectivity and sensitivity, and improved efficiency when quantifying drugs and related compounds in complex matrices such as biological and environmental samples, pharmaceutical formulations, food, and animal feed. In this review we summarize HILIC methods recently developed for drug analysis (2006–2011). In addition, a list of important applications is provided, including experimental conditions and a brief summary of results. The references provide a comprehensive overview of current HILIC applications in drug analysis.      

Stationary phases for hydrophilic interaction chromatography, their characterization and implementation into multidimensional chromatography concepts

Hydrophilic interaction chromatography (HILIC) is becoming increasingly popular for separation of polar samples on polar columns in aqueous-organic mobile phases rich in organic solvents (usually ACN). Silica gel with decreased surface concentration of silanol groups, or with chemically bonded amino-, amido-, cyano-, carbamate-, diol-, polyol-, or zwitterionic sulfobetaine ligands are used as the stationary phases for HILIC separations, in addition to the original poly(2-sulphoethyl aspartamide) strong cation-exchange HILIC material. The type of the stationary and the composition of the mobile phase play important roles in the mixed-mode HILIC retention mechanism and can be flexibly tuned to suit specific separation problems. Because of excellent mobile phase compatibility and complementary selectivity to RP chromatography, HILIC is ideally suited for highly orthogonal 2-D LC-LC separations of complex samples containing polar compounds, such as peptides, proteins, oligosaccharides, drugs, metabolites and natural compounds. This review attempts to present an overview of the HILIC separation systems, possibilities for their characterization and emerging HILIC applications in 2-D off-line and on-line LC-LC separations of various samples, in combination with RP and other separation modes.     

Sample treatment and determination of pesticide residues in fatty vegetable matrices: A review

A demanding task in pesticide residue analysis is yet the development of multi-residue methods for the determination of pesticides in vegetables with relatively high fat content (i.e. edible oils and fatty vegetables). The separation of pesticides and other chemical contaminants from high-fat food samples prior to subsequent steps in the analytical process is yet a challenging issue to which much effort in method development has being applied. This review addresses the main sample treatment methodologies for pesticide residue analysis in fatty vegetable matrices. Even with the advent of advanced hyphenated techniques based on mass spectrometry these complex fatty matrices usually require extensive sample extraction and purification. Current methods involve the use of one or the combination of some of the following techniques for both the sample extraction and clean-up steps: liquid-liquid partitioning, solid-phase extraction (SPE), gel-permeation chromatography (GPC), matrix solid-phase dispersion (MSPD), etc. An overview of methods developed for these contaminants in fatty vegetables matrices is presented. Sample extraction and purification techniques are discussed and their most recent applications are highlighted. This review emphasizes that sample preparation is a critical step, but also the determination method is, and cannot be treated separately from sample treatment. In recent years, the appearance and use of new, more polar pesticides has fostered the development of liquid chromatography/mass spectrometry (LC-MS) besides gas chromatography. The main features of LC-MS for the analysis of multi-class pesticides in fatty vegetable samples will be also underlined, with an emphasis on the multi-class, multi-residue strategy and the difficulties associated.     

Sorptive extraction of pesticides from food and environmental samples using metal organic framework-based adsorbents

Sorptive pre-concentration of pesticide residues in food and environmental samples is increasingly gaining momentum. This can be attributed to fact that most sorptive extraction techniques are solvent-free as well as the availability of emerging sorbents with relatively high adsorption capacities. Metal organic frameworks (MOFs) are among the emerging sorbents that have captured the interests of many researchers during pesticide analysis. There are many types of MOFs that have been used by researchers to pre-concentrate pesticides in food and environmental samples. Some researchers have successfully used MIL-based MOFs during sorptive extraction of pesticides in complex matrices. This review gives a detailed discussion of their application during pesticide pre-concentration. Other researchers have used the ZIF series of MOFs for the sorptive pre-concentration of pesticides in food and environmental samples. The utilisation of the ZIF series of MOFs during pesticide pre-concentration is well-articulated in this review. The review also devoted to the application of UiO and HKUST series of MOFs during the pre-concentration of pesticides in food and environmental samples. In addition, the challenges associated with the use of MOFs during sorptive pre-concentration of pesticides are also discussed in this review.     

Retention and selectivity of stationary phases for hydrophilic interaction chromatography

More and more polar stationary phases have become available for the separation of small polar compounds in the past decade as hydrophilic interaction chromatography (HILIC) continues to find applications in new fields (e.g., metabolomics and proteomics). Bare silica phases remain popular, especially in the bio-analytical area. A wide range of functional groups (e.g., amino, amide, diol, sulfobetaine, and triazole) have been employed as polar stationary phases for HILIC separation. This review provides a survey of the popular stationary phases commercially available and discusses the retention and selectivity characteristics of the polar stationary phases in HILIC. The purpose of the review is not to provide a comprehensive overview of literature reports, but rather focuses on findings that demonstrate retention and selectivity of the polar stationary phases in HILIC.     

分子印迹聚合物在极性农药残留检测中的应用进展

极性农药包括杀菌剂、除草剂、杀虫剂等,种类丰富,成本低廉,在农业中应用广泛,其滥用易导致水资源和土壤等环境污染,人类通过间接接触动植物源性食品和环境中的极性农药残留也增加了农药暴露风险。极性农药的物理化学性质差异大,通常痕量存在于食品和环境样品等复杂基质中,这对其准确检测分析带来了挑战。分子印迹聚合物(MIPs)作为一种人工制备的选择性吸附剂,具有与模板分子在空间结构、大小尺寸和功能基团上互补的特定识别位点,且易于制备,成本低,稳定性好,重复利用率高,已被广泛用于极性农药残留的样品前处理和分析检测中。MIPs可以作为固相萃取(SPE)、固相微萃取(SPME)、磁性固相萃取(MSPE)、搅拌棒固相萃取(SBSE)等前处理方法的吸附剂,还可用于制备光、电、化学传感器,作为质谱检测的离子源基底和拉曼光谱的增强基底。目前针对极性农药残留的检测,已有许多研究报道了多种分子印迹材料用于高效分离分析各种复杂基质中的极性农药残留,但未见此方面的综述报道。该文首先介绍了MIPs的印迹策略、聚合策略,并针对传统MIPs制备和应用中存在的问题,简要概括了一些新型的分子印迹策略和制备技术;然后从极性农药残留分析的角度出发,总结归纳了分子印迹材料近年来特别是近5年来在各种极性农药残留(包括新烟碱类、有机磷类、三嗪类、唑类、脲类等)检测中的应用,并针对现存问题展望了其未来的发展方向和趋势。     

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.     

硅胶色谱柱的亲水作用保留机理及其影响因素

亲水作用色谱（HILIC）是替代反相色谱（RPLC）分离强极性及亲水性化合物的另一色谱模式,其分离机理与RPLC有很大不同,具有和RPLC互补的选择性。在HILIC模式中,采用正相色谱（NPLC）中的极性固定相及含高浓度有机溶剂（通常为乙腈）的水溶液为流动相。硅胶是开发最早、研究最为深入及应用最为广泛的HILIC固定相,本文介绍了硅胶色谱柱的HILIC保留机理,详细概述了操作条件如硅胶柱类型、流动相组成及柱温对HILIC分离的影响,并对硅胶填料色谱柱的HILIC模式的发展方向与应用前景进行了展望。     

The advantages of ESI-MS detection in conjunction with HILIC mode separations: Fundamentals and applications

The analysis of highly hydrophilic, ionic, and polar compounds has been performed by HILIC-ESI-MS for the last few years. The use of low aqueous/high polar organic solvent content in HILIC separation mobile phase is almost ideal for ESI-MS detection in many cases, resulting in increased sensitivity. Although the addition of modifiers such as acids or salts is necessary in some circumstances for a good separation, the optimum concentrations used are still highly amenable for ESI-MS analysis, showing few deleterious effects. In this review, the mechanism of HILIC separation and ESI ion generation will be briefly discussed, followed by a summary of method development and applications in several fields of research including pharmaceutical, biomolecular, food, metabolic, and environmental analysis.     

A survey of polar stationary phases for hydrophilic interaction chromatography and recent progress in understanding retention and selectivity

Various polar stationary phases are available for hydrophilic interaction chromatography (HILIC) and help drive continuous applications in biomedical, environmental, and pharmaceutical areas in the past decade. Although the stationary phases for HILIC have been reviewed previously, it is an appropriate time to take another look at the progresses made during the past 5 years. The current review provides an overview of the polar stationary phases commercially available for HILIC applications in an effort to assist scientists in selecting suitable columns. New types of stationary phases that were published in literature in the past 5 years are summarized and discussed. The trend in stationary phase research and development is also highlighted. Of particular interest is the experimental evidence for direct interactions of polar analytes with the ligands of the stationary phases under HILIC conditions. In addition, two different approaches have been developed to delineate the relative significance of the partitioning and adsorption mechanisms in HILIC, representing an important advancement in our understanding of the retention mechanisms in HILIC.     

Review of the QuEChERS method for the analysis of organic pollutants: Persistent organic pollutants,polycyclic aromatic hydrocarbons,and pharmaceuticals

In multi-residue pesticide analysis, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method has replaced less efficient traditional extraction methods due to its many advantages. In addition to pesticide analysis, this method has been widely used for the detection and analysis of pharmaceuticals, polycyclic aromatic hydrocarbons (PAHs), and several persistent organic pollutants (POPs), including dioxins, polychlorinated biphenyls, perfluoroalkyl substances, and brominated flame retardants in food, biological, and environmental matrices. The analysis of PAHs and POPs is challenging due to the properties of the target compounds and their low concentrations in complex matrices. This review summarizes previously reported the QuEChERS extraction approaches to the analysis of a wide range of analytes. The QuEChERS approaches, which include dispersive solid phase extraction (d-SPE), have generally been combined with either gas chromatography–mass spectrometry (GC–MS) or liquid chromatography–mass spectrometry (LC–MS) analysis. Further on, in recent years, GC and LC-tandem mass spectrometry has been utilized with the QuEChERS extraction due to its high selectivity, sensitivity, and specificity. This enables the extraction methods for target analytes to be modified through the selection of different extraction solvents, salt formulations, and buffers for salting-out partitioning and the selection of different d-SPE and SPE sorbents for the clean-up process. The most significant advantage of this method is that concentration steps are not required. This review aims to provide an up-to-date overview of information regarding the modification of extraction techniques based on target compounds and sample matrices.     

Clean-up techniques for pesticides in fatty foods

The separation of pesticides and other chemical contaminants from high-fat food samples prior to subsequent steps in the analytical process (usually gas chromatography) is a problem to which much effort in method development has been applied. Early methods involved liquid-liquid partitioning, adsorption chromatography and chemical destruction of lipids with strong base and acid. These techniques had limited applicability, especially with the advent of more polar and labile pesticides. Later developments involving sweep codistillation, gel-permeation chromatography and reversed-phase liquid chromatography on alkyl-bonded microparticulate silica are applicable to a wider range of analytes and are generally faster and more efficient and consume less reagents. Supercritical fluid extraction should prove useful in this regard. A brief overview of methods developed for isolating trace levels of environmental contaminants from lipids is presented.     

Recent trends in the liquid chromatography–mass spectrometry analysis of organic contaminants in environmental samples

An overview of liquid chromatography–mass spectrometry methods used for the determination of trace organic contaminants in environmental samples is presented. Among the organic contaminants the focus is given on five groups of emerging contaminants that raised most concern as environmental contaminants and therefore attracted attention of a research community: pharmaceuticals, drugs of abuse, polar pesticides, perfluorinated compounds and nanoparticles. Various aspects of current LC–MS methodology, using tandem and hybrid MS instruments, including sample preparation, are discussed.     

Hydrophilic interaction chromatography

Separation of polar compounds on polar stationary phases with partly aqueous eluents is by no means a new separation mode in LC. The first HPLC applications were published more than 30 years ago, and were for a long time mostly confined to carbohydrate analysis. In the early 1990s new phases started to emerge, and the practice was given a name, hydrophilic interaction chromatography (HILIC). Although the use of this separation mode has been relatively limited, we have seen a sudden increase in popularity over the last few years, promoted by the need to analyze polar compounds in increasingly complex mixtures. Another reason for the increase in popularity is the widespread use of MS coupled to LC. The partly aqueous eluents high in ACN with a limited need of adding salt is almost ideal for ESI. The applications now encompass most categories of polar compounds, charged as well as uncharged, although HILIC is particularly well suited for solutes lacking charge where coulombic interactions cannot be used to mediate retention. The review attempts to summarize the ongoing discussion on the separation mechanism and gives an overview of the stationary phases used and the applications addressed with this separation mode in LC.     

亲水作用色谱填料的研究进展

亲水作用色谱是一种新型的色谱分离模式.此类色谱模式集反相色谱的经济廉价与正相色谱的优点于一体,有效补充了反相色谱的不足.简单介绍实验室中合成的新型亲水色谱固定相.     

Residue analysis of organophosphorus pesticides in food with two-dimensional gas chromatography using capillary columns and flame photometric detection

Two-dimensional gas chromatography with two capillary columns of different polarity (SP 2100 and OV 225) is used for pesticide residue analysis in food samples. By means of “live chromatography” applying pneumatic switching technique according to Deans, unequivocal identification of 57 organophosphorus pesticides in food samples is achieved at trace concentrations. The instrument is equipped with only one injection port and one flame photometric detector. On-line data processing is very helpful, especially in calibration and checking the system's reliability with the multitude of test compounds. The complete pesticide residue analysis including clean-up of about six food samples can be completed by one person in 8 hours.     

Fingerprint analysis of Ligusticum chuanxiong using hydrophilic interaction chromatography and reversed-phase liquid chromatography

Fingerprint analysis is considered one of the most powerful approaches to quality control in traditional Chinese medicines (TCMs). In this study, a binary chromatographic fingerprint analysis was developed using hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) to gain more chemical information about polar compounds and weakly polar compounds. This method was used to construct a chromatographic fingerprint of Ligusticum chuanxiong. The two chromatographic methods demonstrated good precision, reproducibility, and stability, with relative standard deviations of <2% for retention time and 7% for peak area for both HILIC and RPLC separations. Data from the analysis of 14 samples by HILIC and RPLC were processed with similarity analysis, with correlation coefficients and congruence coefficients. This binary fingerprint analysis, using two chromatographic modes, is a powerful tool for characterizing the quality of samples, and can be used for the comprehensive quality control of TCMs.     

Hydrophilic interaction liquid chromatography in food analysis

The use of hydrophilic interaction liquid chromatography (HILIC) in food analysis in the last decade is reviewed. The HILIC mechanism is briefly discussed, but main emphasis is put on the use of HILIC for separation of different food matrices. The food matrices are divided into food of animal origin and related products, vegetables, fruits and related compounds, and other food-related matrices. A list on important applications is provided for each category including experimental conditions and a brief summary of the results. The 100 references included will provide the reader a comprehensive overview and insight into HILIC applications to food analysis.     

以亲水作用色谱为核心的液相色谱联用技术及其应用研究

亲水作用色谱(HILIC)是近年来色谱领域研究的热点之一。本文围绕复杂体系样品中亲水性组分的分离分析,综述了国际上近年 来发展的以HILIC为核心的多种液相色谱联用技术及其应用。简要介绍了HILIC的起源、定义、分离特点及其常用固定相;比较了HILIC和反相色谱(RPLC)的选择特性;针对不同层次的分离对象和分离要求,讨论了多种基于HILIC的液相色谱以及液相色谱-质谱联用技术的分离特点和适用范围。