Monolithic Silica Columns for HPLC,Micro‐HPLC,and CEC

Two types of monolithic silica columns derivatized to form an ODS phase, one prepared in a fused silica capillary (SR‐FS) and the other prepared in a mold and clad with an engineering plastic (poly‐ether‐ether‐ketone) (SR‐PEEK), were evaluated. The column efficiency and pressure drop were compared with those of a column packed with 5‐μm ODS‐silica particles and of an ODS‐silica monolith prepared in a mold and wrapped with PTFE tubing (SR‐PTFE). SR‐FS gave a lower pressure drop than a column packed with 5‐μm particles by a factor of 20, and a plate height of 20 μm at a linear velocity below 1 mm/s. SR‐PEEK showed higher flow‐resistance than the other monolithic silica columns, but they still showed a minimum plate height of 8–10 μm and a lower pressure drop than popular commercial columns packed with 5‐μm particles. The evaluation of SR‐FS columns in a CEC mode showed much higher efficiency than in a pressure‐driven mode.     

Chromatographic Properties of Monolithic Silica Capillary Columns for Polar and Nonpolar Compounds in Reversed-Phase HPLC

Retention properties of monolithic silica C₁₈ columns were examined for polar and nonpolar compounds. Monolithic silica columns were prepared from two kinds of starting materials, tetramethoxysilane (abbreviated as TMOS) or a mixture of TMOS and methyltrimethoxysilane (abbreviated as Hybrid), and modified with dimethyloctadecylchlorosilane (C₁₈). Retention factors of various compounds on Hybrid-C₁₈ are about twice as much as that on TMOS-C₁₈. The two types of columns showed very similar retention selectivity with few exceptions. TMOS-C₁₈ showed slight preference toward planar polynuclear aromatic hydrocarbons (PAHs) compared to bulky aromatic hydrocarbons, while Hybrid-C₁₈ showed opposite tendency. Some TMOS-C₁₈ columns showed peak tailing for PAHs, and also for basic compounds in an acidic mobile phase, while Hybrid-C₁₈ and majority of TMOS-C₁₈ columns resulted in good peak shape for these compounds.     

高效液相色谱整体柱技术研究进展

高效液相色谱整体柱作为一种新型的分离介质,由于其制备工艺简单、易于修饰改性和分离性能优异,近年来引起了人们的广泛关注。聚合物整体柱具有生物相容性好、柱效高、寿命长、选材范围广、重现性好及使用不受p H限制等优势,广泛应用于食品、化工、农业、环境及生物医学领域小分子化合物及蛋白质的分离和检测,显示出较好的应用前景。本文就近10年液相色谱整体柱的制备、改性方法及应用的研究成果进行综述,并对其在不同应用领域的发展前景作了展望。     

毛细管硅胶基质整体柱的制备及其电色谱性能研究

采用热引发一步法制备了毛细管电色谱硅胶基质整体柱。通过使用表面活性剂(十二烷基磺酸钠)增加了反应液中两相之间的相互溶解,使得反应液最终成为均相溶液,实现了硅胶整体柱的均相聚合制备。所制备的均相硅胶整体柱内部结构更加均匀,大大提高了分离度。评价了该整体柱的电色谱性能,深入探讨了有机溶剂比例、pH值、电压以及温度等电色谱操作条件对电渗流、保留机理和柱效的影响。在该均相硅胶基质整体柱上成功地分离了9种中性物质(硫脲、苯、甲苯、乙基苯、正丙苯、萘、正丁基苯、芴和蒽)以及7种中性、酸性和碱性物质(硫脲、邻氨基酚、苯酚、苯、邻甲苯胺、α-萘胺和2,4-二氯苯胺)。该柱对硫脲的柱效超过110000塔板/m。     

Tailoring Mesopores in Monolithic Macroporous Silica for HPLC

Mesopore formation in silica gels having continuous macropores has been investigated. The macroporous wet silica gel prepared by the sol‐gel process including phase separation was aged in a basic solvent making use of hydrolysis of urea in a closed condition. The mesopore structure was finally obtained by subsequent evaporation drying of solvent and heat‐treatment at 600°C for 2 h. The dissolution‐reprecipitation kinetics at the interfaces between wet gel skeletons and an external solvent affected the size and volume of pores formed within the skeletons. Below 120°C, mesopores suitable for various chromatographic applications have been formed typically within 24 h. On the other hand, at 200°C, the pore size attained the macropore dimensions (>50 nm), and the whole macroporous morphology was significantly modified.     

Monolithic Silica for Fast HPLC: Current Success and Promising Future

As an approach for fast HPLC, monolithic silica has proven to be highly effective. It is especially successful for routinely obtaining fast isocratic HPLC analyses of small drug molecules. The low cost of monolithic compared with other approaches, such as UPLC, makes it more convenient for everyday application. It is also the more developed and widely applied technique compared with superficially porous particles. It offers the possibility for gaining high plate numbers through column coupling, but not at the expense of run time if a proper flow program is subsequently applied. Good precision and batch reproducibility are now achieved with commercially available monolithic silica columns. The application of monolithic silica columns is already well developed in various fields. It invades the field of bio-analysis and proteomics. Hundreds of analytical methods have already been successfully transferred to or developed on monolithic silica columns. An updated strategy based on Snyder??s method for rapid method development using monolithic column has been provided. However, more is still to be expected from monolithic silica in term of chemistry variation, application, and instrument compatibility. The future of monolithic silica is promising when considering the high demand for fast chromatographic analysis.     

HPLC Phospholipid Separation Mechanisms on Silica,Amino, and Diol Columns

Abstract

The HPLC separation of phospholipid mixtures was investigated on silica, amino, and diol columns, using mobile phases consisting of acetonitrile, methanol, and phosphoric or trifluoroacetic acids in varying proportions. An explanation of the mechanism of these separations is given with regard to the individual column types.     

Separation of Polar and Basic Compounds in Hydrophilic Interaction Pressurized CEC Using Diethylenetriaminopropyl Silica Monolithic Columns

A novel silica-based monolithic column possessing diethylenetriaminopropyl ligands for hydrophilic interaction pressurized capillary electrochromatography is described. The preparation of monolithic stationary phase was based on the individual silica matrix forming and subsequent chemical bonding. The triamino groups on the surface of the novel stationary phase generated a sustainable anodic electroosmotic flow under acidic conditions. A variety of neutral and basic analytes were used to evaluate the column performance. The monolithic silica stationary phase exhibited hydrophilic interaction chromatographic behavior toward neutral solutes. For basic tetracycline antibiotics, hydrophilic interaction as well as electrophoretic migration process with the monoliths was observed and peak tailing was avoided.     

离子交换整体柱材料的研究进展

综述了近几年来离子交换整体柱材料(包括涂敷型和键合型)的研究进展,重点介绍其制备方法和在环境及生物领域中的应用,分析了离子交换整体柱目前存在的问题,展望了其将来的发展方向。引用参考文献50篇。     

高效液相色谱整体柱技术的进展

高效液相色谱整体柱（又名连续床）具有制备相对简单、原料易得以及聚合组分在一定范围内可调节的优点,是近年来得到迅速发展的新型色谱柱。本文综述了目前高效液相色谱（HPLC）制备整体柱的典型高聚物体系、制备各种整体柱时反应条件的影响,并简要介绍了它的表征方法和应用。     

Monolithic Molecularly Imprinted Columns for Chromatographic Separation

Monolithic molecularly imprinted columns are a new class of column that emerged in the early 1990s. These monolithic materials are typically prepared directly inside stainless steel columns or capillary columns without the tedious procedures of grinding, sieving, and column packing. Furthermore, the preparation of this type of MIP is more cost-efficient, because the amount of template molecules required is much lower. In recent years monolithic supports as stationary phases in high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) have attracted significant interest because of their ease of preparation, high reproducibility, versatile surface chemistry, and rapid mass transport.     

硅胶整体柱的研究进展

自液相色谱技术创立以来,色谱填充材料经历了4个发展阶段[1],包括从形状不规则的填充颗粒到球形颗粒填料、从大的颗粒到小的填充颗粒、从不纯的填充材料到高纯的球形硅胶颗粒以及目前整体柱的产生,一直在向着提高柱效和实现快速分离的方向发展。与整体柱相比,传统的液相色谱柱存在种种弊端和限制[2,3],人们为了提高颗粒型填充柱的柱效而使用越来越小的填料,但柱压降随填料粒度的减小却急剧上升。因此,综合柱效和分离速度两方面因素,较为折中的5μm填料被广泛使用。换句话讲,传统的高效液相色谱(HPLC)填充柱对分离对象很难同时实现既高…     

硅胶整体柱芯的制备方法研究

目前,新型色谱填充材料发展很快,但传统的高效液相色谱(HPLC)颗粒型填充柱存在缺陷,难以实现既高效又快速的分离,Minakuchi等制备了连续的硅胶整体柱,该柱同时具有通孔和中孔双孔结构,孔容量大大高于填充柱,因此,该柱具有高速、低压、高效、适于溶剂及流速梯度洗脱等优点,适合高通量分析和快速分离,     

One-Step Synthesis of Monolithic Silica Nanocomposites in Fused Silica Capillaries

The ideal way to prepare efficient, yet robust stationary phases for microanalytical high-resolution methods such as capillary chromatography and electrochromatography remains to be defined. In this contribution a one step sol-gel process is proposed for the production of monolithic, macroporous nanocomposite phases in fused silica capillaries, which require no additional derivatization, since they already bear the interactive (C8) moieties. The effect of the catalyst, the water content, the pH, as well as that of certain additives on monolith formation and porosity is investigated. Volume shrinkage and a tendency to crack were the major obstacles to overcome. Homogeneous stationary phases could be produced by applying a pH gradient during sol formation, thereby changing the catalytic principle from acidic (0.1 M HCl) to basic (gradual formation of OH^– as a consequence of the hydrolysis of N-methylformamide). Gelation/coacervation of suchgels could be induced by the addition of N,N-diethylamine. The water content during sol formation was determined as decisive for pore formation, with 250% of the amount theoretically needed for complete hydrolysis of all precursors giving optimal results. The volume shrinkage problem during xerogel formation was resolved by integrating dialkyldialkoxysilane units (dimethyldiethoxysilane 35 mol%) into the silica network.     

毛细管硅胶整体柱的研究进展

硅胶整体柱由于具有高的机械强度、良好的耐溶剂性能及通透性等优点,在近几年受到了越来越多的关注,并已应用于微柱液相色谱和毛细管电色谱.该文从分离模式的角度,对近两年毛细管硅胶整体柱的制备方法及其应用进行了系统的综述,并展望了这一领域未来的发展趋势.     

阴离子交换整体柱对蛋白质的分离与纯化

分别用乙二胺、二乙胺、三乙胺将自制的以甲基丙烯酸缩水甘油酯(GMA)为单体、乙二醇二甲基丙烯酸酯(EDMA)为交联剂的整体柱修饰为弱、强阴离子交换整体柱。考察了该整体柱的性能,选择出分离蛋白质(牛血清白蛋白、溶菌酶和谷胱甘肽)的最佳实验条件,并在最佳分离条件下考察了这些蛋白质在整体柱上的色谱行为和该整体柱对纤维素降解酶的分离纯化情况。实验结果表明,该整体柱性能良好,可以实现对纤维素降解酶的快速分离与纯化。同时,实验也证明采用梯度洗脱可以实现对某些蛋白质的分离纯化。     

Rapid Preparation of Monolithic Columns for Capillary Electrochromatography Separation

Sol-gel technology can provide a versatile approach to the synthesis of organic polymers and organic-inorganic hybrid materials applied in HPLC, micro-HPLC and capillary electrochromatography (CEC)1. It can take place under extraordinarily mild thermal co…     

Synthesis of Monolithic Silica Gel in Alkaline Medium

The influence exerted by the basicity and nucleophilicity of a number of organic amines on the formation of a monolithic silica gel by the organic sol-gel method was studied.