毛细管离子色谱分析系统研究进展

离子色谱是目前分析离子型样品的成熟技术,其水相工作介质的特点相对于液相色谱更适合于生物样品的分析。毛细管离子色谱(CIC)由于其节省样品的特点在生物分析方面的优势更为明显。CIC大体上可分为开管型、填充柱型和整体柱型3种类型。本文以填充型CIC几大关键部件技术发展为主线,综述了近年来CIC的研究进展。     

Selective capillary coating materials for in-tube solid-phase microextraction coupled to liquid chromatography to determine drugs and biomarkers in biological samples: A review

In-tube solid-phase microextraction (in-tube SPME) coupled with high performance liquid chromatography (HPLC) or liquid chromatography coupled to mass spectrometry (LC-MS) successfully determines drugs or biomarkers in biological samples by direct sample injection or by simple sample treatment. This technique uses a capillary column as extraction device. Several capillaries (wall-coated open tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with unique phases have been developed and evaluated, aiming to improve the efficiency and selectivity of the in-tube SPME-LC technique. This review describes new developments and applications occurred in recent years, and discusses future trends with emphasis on new extraction devices and current technology used for the synthesis of selective sorbents for bioanalysis, such as (i) polypyrrole, (ii) restricted-access materials, (iii) immunosorbents, (iv) molecular imprinting polymers, (v) monolithic polymers, and (vi) bi-functional materials.     

Capillary ion chromatography

This review summarizes progress in capillary ion chromatography. Theoretical aspects and practical limitations of packed and open tubular capillary columns are considered. Applications of packed and open tubular capillary IC are described. Emerging technologies such chip-scale IC and the use of monolithic columns are discussed.     

Silica monolithic membrane as separation medium. Summable property of different membranes for high-performance liquid chromatographic separation

We studied an applicability of a silica monolithic membrane as separation medium for high-performance liquid chromatography (HPLC). We prepared porous monolithic silica membranes having a three-dimensional network structure to cut and shape into a membrane separation medium. We evaluated chromatographic properties of a variety of solutes using a column containing the membranes with HPLC to elucidate summable property of the membrane separation media. In addition, we made brief study on separation of HbA1c in whole blood with the stacked" membranes having different surface characteristics in one column, which is a membrane column. We confirmed that the membrane column was able to separate HbA1c from other matrix in whole blood to some extent, and it also had an excellent ability for hydrophobic and ion exchange adsorption.     

A cation exchange resin bead-based microscale electrolytic suppressor for capillary ion chromatography

A cation exchange resin (CER) bead-based microscale electrolytic suppressor for capillary ion chromatography (CIC) has been fabricated and evaluated. Relative to common ion exchange membrane, the use of CER beads presents a simple way to fabricate a microscale suppressor due to its small surface area and spherical shape. The internal volume of the device is ∼600 nL, which matches the requirements by CIC. Continuous online regeneration is readily achieved using pure water or diluted sulfuric acid as the regenerant. The use of a cation exchange functionalized monolithic segment inserted between two CER beads greatly reduces the electrical resistance and improves the suppression efficiency. The device works well only in the electrolytic mode, chemical regeneration alone is ineffective. The suppressed background is ∼3 μS/cm for 10 mM KOH eluent generated online by a microscale KOH electrolytic generator operated at the flow rate of 3 μL/min. The preliminary application for capillary ion chromatography has been demonstrated.     

Polymethacrylate monolithic columns for capillary liquid chromatography

In recent years, continuous separation media have attracted considerable attention because of the advantages they offer over packed columns. This research resulted in two useful monolithic material types, the first based on modified silica gel and the second on organic polymers. This work attempts to review advances in the development, characterization, and applications of monolithic columns based on synthetic polymers in capillary chromatography, with the main focus on monolithic beds prepared from methacrylate-ester based monomers. The polymerization conditions used in the production of polymethacrylate monolithic capillary columns are surveyed, with attention being paid to the concentrations of monomers, porogen solvents, and polymerization initiators as the system variables used to control the porous and hydrodynamic properties of the monolithic media. The simplicity of their preparation as well as the possibilities of controlling of their porous properties and surface chemistries are the main benefits of the polymer monolithic capillary columns in comparison to capillary columns packed with particulate materials. The application areas considered in this review concern mainly separations in reversed-phase chromatography, ion-exchange chromatography, hydrophobic and hydrophilic interaction modes; enzyme immobilization and sample preparation in the capillary chromatography format are also addressed.     

毛细管离子色谱进展

从毛细管离子色谱柱制备和毛细管离子色谱仪器研制两方面评述了毛细管离子色谱目前的发展状况。毛细管离子色谱柱包括开管离子色谱柱，毛细管颗粒填充离子色谱柱以及最近几年发展起来的整体毛细管离子色谱柱。对毛细管离子色谱仪的总结包括微流量泵、小体积进样器、适合毛细管离子色谱系统的小体积抑制器、电导和光学检测器等。     

Applications of monolithic columns in gas chromatography and supercritical fluid chromatography

Porous monoliths are well‐known stationary phases in high‐performance liquid chromatography and capillary electrochromatography. Contrastingly, their use in other types of separation methods such as gas or supercritical fluid chromatography is limited and scarce. In particular, very few studies address the use of monolithic columns in supercritical fluid chromatography. These are limited to silica‐based monoliths and will be covered in this review together with an underlying reason for this trend. The application of monoliths in gas chromatography has received much more attention and is well documented in two reviews by Svec and Kurganov published in 2008 and 2013, respectively. The most recent studies, covered in this review, build on the previous findings and on further understanding of the influence of preparation conditions on porous properties and chromatographic performance of poly(styrene‐co‐divinylbenzene), polymethacrylate, and silica‐based monolithic columns while expanding to polymer‐based monoliths with incorporated metal organic frameworks and to vinylized hybrid silica monoliths. In addition, the potential application of porous layer open tubular monolithic columns in low‐pressure gas chromatography will be addressed.     

离子色谱整体固定相的最新进展

整体固定相是近年来新兴的一种多孔性固定相介质,它在离子态及极性化合物的分离中得到了越来越广泛的重视。本文就离子色谱领域整体固定相的发展以及最新的研究动向进行了综述,讨论了离子色谱整体固定相的优点、分类以及在分离分析离子态物质方面的应用等。     

Review on recent and advanced applications of monoliths and related porous polymer gels in micro-fluidic devices

This review critically summarises recent novel and advanced achievements in the application of monolithic materials and related porous polymer gels in micro-fluidic devices appearing within the literature over the period of the last 5 years (2005-2010). The range of monolithic materials has developed rapidly over the past decade, with a diverse and highly versatile class of materials now available, with each exhibiting distinct porosities, pore sizes, and a wide variety of surface functionalities. A major advantage of these materials is their ease of preparation in micro-fluidic channels by in situ polymerisation, leading to monolithic materials being increasingly utilised for a larger variety of purposes in micro-fluidic platforms. Applications of porous polymer monoliths, silica-based monoliths and related homogeneous porous polymer gels in the preparation of separation columns, ion-permeable membranes, preconcentrators, extractors, electrospray emitters, micro-valves, electrokinetic pumps, micro-reactors and micro-mixers in micro-fluidic devices are discussed herein. Procedures used in the preparation of monolithic materials in micro-channels, as well as some practical aspects of the micro-fluidic chip fabrication are addressed. Recent analytical/bioanalytical and catalytic applications of the final micro-fluidic devices incorporating monolithic materials are also reviewed.     

Recent developments of monolithic and open‐tubular capillary electrochromatography (2017–2019)

Capillary electrochromatography, which combined the high selectivity of high‐performance liquid chromatography and the high separation efficiency of capillary electrophoresis, is an attractive separation tool. In this review, the developments on monolithic and open tubular capillary electrochromatography during 2017 to August 2019 are summarized. Considering the development of novel stationary phases is the most active research field in capillary electrochromatography, monolithic capillary electrochromatography is classified according to the polymer‐based and hybrid monolithic columns, while open‐tubular capillary electrochromatography is categorized by cyclodextrin, silica, polymer, nanomaterials, microporous materials, and biomaterials‐based open tubular columns.     

Developments in ion chromatography using monolithic columns

The focus of this review is on current status and on-going developments in ion chromatography (IC) using monolithic phases. The use and potential of both silica and polymeric monoliths in IC is discussed, with silica monoliths achieving efficiencies upwards of 10(5) plates/m for inorganic ions in a few minutes or less. Ion exchange capacity can be introduced onto the monolithic columns through the addition of ion interaction reagents to the eluent, coating of the monolith with ionic surfactants or polyelectrolyte latexes, and covalent bonding. The majority of the studies to date have used surfactant-coated columns, but the stability of surfactant coatings limits this approach. Applications of monolithic IC columns to the separation of inorganic anions and cations are tabulated. Finally, a discussion on the recent commercialization of monolithic IC columns and the use of monolithic phases for IC peripherals such as preconcentrator columns, microextractors and suppressors is presented.     

‘Fast atom bombardment’—A rediscovered method for mass spectrometry

In 1966, Devienne and co-workers studied extensively the sputtering of various target materials by a high energy molecular beam obtained by charge exchange. They obtained secondary ions that characterized for instance, organic and biological materials. These ions were analysed by mass spectrometry. This method was developed to be patented and many devices were studied. The principle of the apparatus constructed is very simple. An ion source produces an ion current of some microamperes. The ions are accelerated at some keV, and injected into a collision chamber in order to obtain a neutral beam by resonant charge exchange. The residual ions are deflected and this beam bombards the target. The target itself is surrounded by a small metal cylinder which is held at an appropriate potential to extract the positive or negative secondary ions formed. The ion beam is accelerated and focused into the entrance slit of a mass spectrometer. After the first devices, two types of apparatus were built in 1973 and 1975. With the first one, the analysis of the masses was obtained only by an electromagnet. The energy range of the secondary ions varied from 1 to 10 keV. The second apparatus was formed by an electromagnet, a dissociation chamber, and an electrostatic analyser. With this apparatus, it was possible to measure directly masses as large as 6000 daltons. With the first apparatus it was possible to study the adsorption of oxygen on silicon, and to obtain spectra, of many organics such as camphor, nitrodiphenylamine and, as in the earlier device, the spectrum of a non-volatile organic liquid diethylhexyl azelate, was obtained. After studies on different uranium compounds and their dissociations, the second apparatus was devoted to the formation and study of the chemical properties of clusters.     

High‐throughput gas chromatography for volatile compounds analysis by fast temperature programming and adsorption chromatography

The synergy of combining fast temperature programming capability and adsorption chromatography using fused silica based porous layer open tubular columns to achieve high throughput chromatography for the separation of volatile compounds is presented. A gas chromatograph with built‐in fast temperature programming capability and having a fast cool down rate was used as a platform. When these performance features were combined with the high degree of selectivity and strong retention characteristic of porous layer open tubular column technology, volatile compounds such as light hydrocarbons of up to C₇, primary alcohols, and mercaptans can be well separated and analyzed in a matter of minutes. This analytical approach substantially improves sample throughput by at least a factor of ten times when compared to published methodologies. In addition, the use of porous layer open tubular columns advantageously eliminates the need for costly and time‐consuming cryogenic gas chromatography required for the separation of highly volatile compounds by partition chromatography with wall coated open tubular column technology. Relative standard deviations of retention time for model compounds such as alkanes from methane to hexane were found to be less than 0.3% (n = 10) and less than 0.5% for area counts for the compounds tested at two levels of concentration by manual injection, namely, 10 and 1000 ppm v/v (n = 10). Difficult separations were accomplished in one single analysis in less than 2 min such as the characterization of 17 components in cracked gas containing alkanes, alkenes, dienes, branched hydrocarbons, and cyclic hydrocarbons.     

无机-有机复合聚合物:材料研究的一个新领域

无机-有机复合聚合物特别是类分子筛聚合物、类多层钙钛矿和仿生物材料的合成及其应用研究成为近几年来一个热门的研究领域。我们瞄准了这一前沿领域并合成和表征了以下四个系列具有纳米孔洞的分子笼和一维、二维或三维的新型无机聚合物:(1)带有纳米尺寸空腔和孔状结构的新型过渡金属和稀土金属聚合物;(2)含有螺旋链的一维链状聚合物;(3)具有石墨形态层状结构和优异导电性能的聚合物;(4)以强金属-金属相互作用为核心、有机分子为稳定外壳的纳米线聚合物。本文总结这四个系列化合物的合成结构和特性。     

Carbon nanotubes in emulsion‐templated porous polymers: Polymer nanoparticles,sulfonation, and conductivity

Sulfonated polymers are of interest for ion exchange resins, reaction supports, and membranes for separation, filtration, fuel cells, and electrochemical devices. Sulfonic groups have been introduced into polystyrene (PS) through exposure to sulfuric acid, and carbon nanotubes (CNTs) have been added to polymers to enhance proton conductivity without creating an electronic percolation pathway. PolyHIPEs, emulsion‐templated porous polymers with highly interconnected hierarchical open‐cell porous structures, are synthesized through polymerization in the external phases of high internal phase emulsions (HIPEs). In this article, the synthesis of PS‐based CNT‐filled polyHIPEs, their structure, sulfonation, and conductivity are described. Adding CNT dispersions to the HIPEs produced polymer nanoparticle–covered polyHIPEs from polymerization within the water‐soluble surfactant micelles in the internal aqueous phase droplets. The CNTs migrated from the HIPE's aqueous phase droplets into the HIPE's organic phase and formed interconnected bundles within the polyHIPE walls, reflecting a reduction in the surfactant's ability to disperse the CNTs. The water adsorption in the hygroscopic sulfonated polyHIPEs increased the conductivity by several orders of magnitude. The conductivity of the sulfonated polyHIPE containing CNTs was more than an order of magnitude greater than that of the sulfonated polyHIPEs with no CNTs. The CNTs act as “bridges,” enhancing the connection between existing conductive pathways. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4369–4377     

Electrochemistry of capillary systems with narrow pores. VI. Convection conductivity (theoretical considerations)

Generally, the electrical convection current and the electrical convection conductivity (Smoluchowski's surface conductivity) have to be taken into account to describe transport phenomena across membranes with narrow pores although the electrical charge distribution within the pores cannot be described as a Helmholtz electrical double layer. In collodion membranes, which have a comparatively low fixed ion concentration, the contribution of the convection conductivity to the electrical conductivity of the pore fluid may be neglected. This assumption was made tacitly in the analysis of our data obtained with this type of membrane.

In this communication equations are derived which take the convection conductivity into account. They are in agreement with the phenomenological transport equations developed by Staverman on the basis of the thermodynamics of irreversible processes.

The electrical convection conductivity can be considered to be the contribution of the fixed ion concentration to the electrical conductivity. It is argued that this contribution cannot be neglected in ion exchange membranes with a high fixed ion concentration and a high mechanical permeability. Neglecting the electrical convection conductivity in such systems could lead to considerable differences between experimental conductivity data and the theoretical predictions. An electrical conductivity term for the fixed ions is proposed which can be used as a correction factor in the equations in which the contribution of the electrical convection conductivity has been neglected. Suggestions are made for the measurement of the electrical convection conductivity in systems with narrow pores and high electrical conductivity (e.g. ion exchange resins). The consequences of the electrical convection conductivity in practical applications of ion-exchange resins are discussed (acceleration of the rates of ion exchange; improvement of the separation properties by the application of a direct electrical current flow).     

开管离子色谱柱的制备与表征

近年来,开管离子色谱(OTIC)的研究已取得重大进展,尤其是兼容OH^-淋洗液的OTIC柱的成功研制使OTIC梯度洗脱得以实现。该文介绍了各种OTIC柱的制备和表征方法,涵盖早期的二氧化硅开管柱和新近出现的有机聚合物基质开管柱,对静电乳胶附聚的OTIC柱的一系列表征方法进行了系统阐述,包括开管柱柱容量的实验测定和理论计算方法、固定相相同时填充柱与开管柱之间的联系、柱效改善方法以及开管柱均一性表征等。     

Electrochemistry of capillary systems with narrow pores. VI. Convection conductivity (theoretical considerations)

Generally, the electrical convection current and the electrical convection conductivity (Smoluchowski's surface conductivity) have to be taken into account to describe transport phenomena across membranes with narrow pores although the electrical charge distribution within the pores cannot be described as a Helmholtz electrical double layer. In collodion membranes, which have a comparatively low fixed ion concentration, the contribution of the convection conductivity to the electrical conductivity of the pore fluid may be neglected. This assumption was made tacitly in the analysis of our data obtained with this type of membrane.In this communication equations are derived which take the convection conductivity into account. They are in agreement with the phenomenological transport equations developed by Staverman on the basis of the thermodynamics of irreversible processes.The electrical convection conductivity can be considered to be the contribution of the fixed ion concentration to the electrical conductivity. It is argued that this contribution cannot be neglected in ion exchange membranes with a high fixed ion concentration and a high mechanical permeability. Neglecting the electrical convection conductivity in such systems could lead to considerable differences between experimental conductivity data and the theoretical predictions. An electrical conductivity term for the fixed ions is proposed which can be used as a correction factor in the equations in which the contribution of the electrical convection conductivity has been neglected. Suggestions are made for the measurement of the electrical convection conductivity in systems with narrow pores and high electrical conductivity (e.g. ion exchange resins). The consequences of the electrical convection conductivity in practical applications of ion-exchange resins are discussed (acceleration of the rates of ion exchange; improvement of the separation properties by the application of a direct electrical current flow).     

Manipulating adenoviral vector ion‐exchange chromatography: Hexon versus fiber

The serotype specificity of adenovirus ion‐exchange chromatography has previously been studied using standard particle‐based columns, and the hexon protein has been reported to determine retention time. In this study, we have submitted Adenovirus type 5 recombinants to anion‐exchange chromatography using methacrylate monolithic supports. Our experiments with hexon‐modified adenoviral vectors show more precisely that the retention time is affected by the substitution of amino acids in hypervariable region 5, which lies within the hexon DE1 loop. By exploring the recombinants modified in the fiber protein, we have proven the previously predicted chromatographic potential of this surface constituent. Modifications that preserve the net charge of the hexon protein, or those that cause only a small charge difference in the fiber protein, in addition to shortening the fiber shaft, did not change the chromatographic behavior of the adenovirus particles. However, modifications that include the deletion of just two negatively charged amino acids in the hexon protein, or the introduction of a heterologous fiber protein, derived from another serotype, revealed recognizable changes in anion‐exchange chromatography. This could be useful in facilitating chromatography‐approach purification by creating targeted capsid modifications, thereby shifting adenovirus particles away from particular interfering substances present in the crude lysate.