New GC quartz-lined aluminum capillary columns coated with graphitized carbon black modified by liquid phases

Summary Fused silica is by far the best material for most kinds of GC capillary columns but in some particular conditions, when a drastic or alkaline treatment is required, this material and especially the polyimide protector layer do not possess high chemical resistance and could easily break down. In order to overcome this disadvantage, in this paper, we present a new type of column — a quartz-lined aluminum capillary coated with graphitized carbon black modified by liquid phases by using a new coating procedure. With the above material a capillary column for amine analysis, and another for the analysis of VOCs and oil products are obtained. Some characteristic applications of both columns are reported.     

Packing columns for capillary electrochromatography

Considering the current interest in capillary electrochromatography (CEC), performed in packed columns, we present the different methods used to pack capillary columns for use in CEC. General considerations on column packing are given and the column fabrication process is discussed in sufficient detail to allow instruction to those who are not experienced in the field. Five different packing methods are discussed to deliver packing material into the capillary column from a practical view point: slurry pressure packing, packing with supercritical CO2, electrokinetic packing, using centripetal forces, and packing by gravity. Entrapment of particulate material by sintering and sol-gel technology is also mentioned. Although slurry pressure packing procedures are most common, higher separation efficiencies are obtained using other packing approaches. Electrokinetic packing seems to be the simplest technique to deliver the packing material into the capillary columns. Nevertheless, as with the other packing techniques, skill and experience are required to complete all the steps involved in the fabrication of packed columns for CEC.     

Preparation of glass capillary columns

Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns. Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.     

Metal oxide monolithic columns

Metal oxide monoliths composed of ZrO2 and HfO2 have been synthesized in situ inside capillary columns. The material shows globular-like structure and through pores. Capillary electrochromatography and capillary liquid chromatography were performed in a monolithic column with the HfO2 material. Separation of a simple sample mixture showed the potential of the new metal oxide monolithic columns.     

New materials and packing techniques for micro-HPLC packed capillary columns

Summary Plastic tubing of polyetheretherketone (PEEK) is used for the preparation of HPLC packed capillary columns. The polymer is rigid but not fragile, has great resistance to chemical and physical agents and comes in standard 1/16″ O.D. These features can extend the column lifetime and facilitate the overall employment of HPLC capillary columns. Serial connection of short columns is also possible with no increase in dead volume. A new, rapid and effective packing method has been developed to be compatible with the characteristics of the material. Several C8 and C18 columns have been prepared and tested and some applications are shown.     

Preparation of High Performance Alumina PLOT Columns and Analysis of Light Hydrocarbons

With the introduction of new capillary column coating technique.It has been realized to prepare gas chromatograph of very high resolution. There has been continued interest in extending the use of GSC adsorbent to capillary chromatography. Currently the film built up on the inner surface of the capillary column can be quite homogeneous and the separation efficiency of the column is increased as well. There have been numerous papers that describe the preparation of PLOT columns in detail. However, Owing to the complexity of the preparation of porous layer for capillary GSC. It is still urgently need to extensively study the preparation process in order to get desired capillary columns of high quality and good reproducibility. This paper describe a new coating method of high performance PLOT columns with alumina by means of liquid phase deposition other than dynamic or static coating techniques. The selectivity, reproducibility and separation power of the column in analysis of light hydrocarbons were examined.     

溶胶-凝胶法制备毛细管硅胶整体柱的研究进展

毛细管硅胶整体柱作为一种新型的分离介质,在色谱领域显示出了强大的生命力。本评述介绍了溶胶-凝胶法制备毛细管硅胶整体柱的方法,重点分析了溶胶-凝胶法制备毛细管硅胶整体柱的影响因素,总结了近几年毛细管硅胶整体柱在高效液相色谱和电色谱中的应用。     

Stimultaneous quantitative analysis using dual capillary columns of different polarities

Complex organic mixtures, such as coal liquefaction and oil shale products and by-products, are comprised of hundreds or thousands of individual components. State-of-the-art high resolution gas chromatography does not always provide sufficient resolution to allow accurate quantitation or identification of many compounds of interest. The concept of dual capillary column chromatography combines the different resolving characteristics of two capillary columns coated with different stationary phases into a single chromatographic run. In this approach, both columns are connected to the same injection port. Analysis of complex mixtures in this fashion can confirm the identification and quantitation of components on two columns of different polarity with little increased analysis time, can provide a means of obtaining quantitative data for individual components which are known to coelute on any one column, and can alert one to unknown coelution problems that would be undetected by gas chromatographic analysis on a single capillary column. Simultaneous dual column analysis was applied to three samples, the neutral polycyclic aromatic hydrocarbon (PAH) fraction of a Solvent Refined Coal-II (SRC-II) heavy distillate, the nitrogen-containing polycyclic aromatic compound (N-PAC) fraction of an SRC-II heavy distillate, and the basic fraction from a shale oil process water. Fused silica capillary columns coated with SE-54 and Durawax 3 were used for the analyses of the heavy distillate, while SE-54 an Carbowax 20M capillary columns were used for the analysis of the process water.     

Fitting adsorption isotherms to the distribution data determined using packed micro-columns for high-performance liquid chromatography

Knowing the adsorption isotherms of the components of a mixture on the chromatographic system used to separate them is necessary for a better understanding of the separation process and for the optimization of the production rate and costs in preparative high-performance liquid chromatography (HPLC). Currently, adsorption isotherms are usually measured by frontal analysis, using conventional analytical columns. Unfortunately, this approach requires relatively large quantities of pure compounds, and hence is expensive, especially in the case of pure enantiomers. In this work, we investigated the possible use of packed micro-bore and capillary HPLC columns for the determination of adsorption isotherms of benzophenone, o-cresol and phenol in reversed-phase systems and of the enantiomers of mandelic acid on a Teicoplanin chiral stationary phase. We found a reasonable agreement between the isotherm coefficients of the model compounds determined on micro-columns and on conventional analytical columns packed with the same material. Both frontal analysis and perturbation techniques could be used for this determination. The consumption of pure compounds needed to determine the isotherms decreases proportionally to the second power of the decrease in the column inner diameter, i.e. 10 times for a micro-bore column (1 mm I.D.) and 100 times for capillary columns (0.32 mm I.D.) with respect to 3.3 mm I.D. conventional columns.     

Two-Dimensional Gas Chromatography. Concepts,Instrumentation, and Applications – Part 1: Fundamentals,Conventional Two-Dimensional Gas Chromatography,Selected Applications

The writer of this review published in 1978 a three-part article on two-dimensional gas chromatography in the first three issues of this journal [1]. The review was written at a time when capillary column GC was still in its infancy. Commercial columns were (essentially) unavailable and sample introduction into capillary columns was done exclusively in the split mode. Two-dimensional separations were explored in only a few laboratories. The limitations of capillary column technology made this exercise rather difficult. The introduction of fused silica capillary columns in the early eighties drastically changed the landscape in which gas chromatography was practiced. It took the chromatographic community just a few years to convert from packed columns to capillary columns. Instrumentation and accessories specifically designed for capillary column use came onto the market. This writer had great hopes that the revolution in capillary column GC would be mirrored in the development of instrumentation for Two-Dimensional Gas Chromatography. This never materialized. On the contrary, tentative steps taken by a few manufacturers and suppliers of chromatographic equipment fizzled out. It was perhaps the introduction of relatively inexpensive and user friendly GC/MS instrumentation, in combination with nearly indestructible fused silica capillary columns that took away the incentive to develop commercially viable Two-Dimensional Gas Chromatography. Much of the thinking went like this: why insist on good chromatography if mass spectrometry can do the job without the need for complete separation. Some progress in the further development of conventional Two-Dimensional Gas Chromatography has certainly been made over the last 20 years but there has not been a great deal of excitement. Applications have also been relatively sparse and they are limited to just a few areas. Science does not remain static and chromatography is no exception. Progress in gas chromatography is driven by new technology and ideas. Substantial improvements in two-dimensional GC were not forthcoming until Phillips and his research group introduced and implemented an entirely new form of Two-Dimensional Gas Chromatography, called comprehensive two-dimensional GC, or GC×GC. This breakthrough occurred only in 1991 [2]. It does take some time before scientists change attitudes and habits. There is always a time lag between the introduction of new technology and its general acceptance. The public's attitude toward comprehensive Two-Dimensional Gas Chromatography is probably no exception. The number of scientists who are actively pursuing this new branch of gas chromatography is still very small. It is often a single individual who carries the torch. J.B. Phillips' name is synonymous with comprehensive Two-Dimensional Gas Chromatography. He is not only its inventor and proponent but his fertile mind has initiated research in other related areas. Sadly, he passed away shortly before this review was written. This contribution is dedicated to his memory.     

Preparation and use of packed capillary columns in chromatographic and related techniques

In this paper general considerations related to the various approaches and parameters influencing the preparation of highly efficient and stable capillary columns for use in liquid chromatography and related techniques are presented and the column production process is discussed in some detail. The different packing methods available for delivering a packing material into a capillary column are discussed from a practical viewpoint. Packing with a gas (dry packing), packing with a liquid solvent or a mixture of solvents (slurry packing), packing with supercritical carbon dioxide, electrokinetic packing, and sol-gel packing technologies are introduced and discussed throughout the paper. Practical recommendations for obtaining highly efficient (high plate numbers) and stable capillary packed columns are also addressed and discussed.     

A capillary gas chromatographic column with a porous layer based on a mesoporous material

A procedure for synthesizing an MSM-41-type mesoporous mesophase material (MMM) layer, that is, a layer of a solid porous material with a regular arrangement of nanoscale calibrated pores and a unified geometry, on the inner wall of a capillary column was developed. Because of the high specific surface area of silica, capillary columns with a porous MMM layer on the basis of silica allow the amount of samples introduced to be increased by an order of magnitude compared with the known capillary porous-layer columns. An example of the separation of light hydrocarbons is described. The properties of columns with MMM porous layers are discussed.     

A novel in situ strategy for the preparation of a β‐cyclodextrin/polydopamine‐coated capillary column for capillary electrochromatography enantioseparations

Inspired by the chiral recognition ability of β‐cyclodextrin and the natural adhesive properties of polydopamine under alkaline conditions, in this study, a rapid and in situ modification strategy was developed to fabricate β‐cyclodextrin/polydopamine composite material coated‐capillary columns for open tubular capillary electrochromatography. The results of scanning electron microscopy, FTIR spectroscopy, streaming potential, and electro‐osmotic flow studies indicated that β‐cyclodextrin/polydopamine was successfully fixed on the inner wall of the capillary column. This coating can be achieved within 1 h affording a greatly reduced capillary preparation time. The performance of the β‐cyclodextrin/polydopamine‐coated capillary was validated by the analysis of seven pairs of chiral analytes, namely epinephrine, norepinephrine, isoprenaline, terbutaline, verapamil, tryptophane, carvedilol. Good enantioseparation efficiencies were achieved for all. For three consecutive runs, the relative standard deviations for the migration times of the analytes for intraday, interday, and column‐to‐column repeatability were in the range of 0.41–1.74, 1.03–4.18, and 1.66–8.24%, respectively. Moreover, the separation efficiency of the β‐cyclodextrin/polydopamine‐coated capillary column did not decrease obviously over 90 runs. The strategy should also be feasible to introduce and immobilize other chiral selectors on the inner walls surface of capillary columns.     

电填充毛细管色谱柱性能的评价

报道了一种毛细管色谱柱的电填充技术,并进行了柱性能的评价研究。实验表明新的填充方法确保了色谱柱的柱效和重现性。     

Capillary liquid chromatography and capillary electrochromatography using silica hydride stationary phases

A hydride-based octadecyl stationary phase on both 4.0 and 1.8 microm silica particles is tested in both the capillary LC and the pressurized capillary electrochromatography (pCEC) modes. These two materials are compared to standard C18 stationary phase made by organosilanization and to the hydride material packed into a convention 4.6mm I.D. column. The performance of the capillary columns is evaluated in terms of analysis times for various mixtures as well as efficiency. Of particular interest are the differences between the LC mode where only laminar flow is present and pCEC operation where a flat electrodriven flow profile is superimposed on the parabolic pressurized flow. Differences in performance between columns packed with 4.0 and 1.8 microm particle silica are also evaluated.     

不锈钢宽口径填充毛细管液相色谱柱

 设计了一种零死体积的二通式柱尾结构和一种使匀浆填料均匀进入色谱柱管内的储料池 ,研究了制备内径在 0 5mm～ 1 0mm的不锈钢宽口径填充毛细管液相色谱柱的方法。详述了以不同牌号、规格的反相ODS类固定相制备的不同柱长的色谱柱的性能。通过折合板高 /折合流速关系和不对称因子对柱性能进行了评价 ,结果表明 ,该方法制备的色谱柱柱效达到理论值的 75 %以上、RSD为 6% ,稳定性也很好。将其应用于抗癫痫药物和氯苯类化合物的分析 ,结果令人满意。     

Ultrahigh-pressure liquid chromatography using a 1-mm id column packed with 1.5-microm porous particles

The evolution of chromatography has led to the reduction in the size of the packing materials used to fabricate HPLC columns. The increase in the backpressure required has led to this technique being referred to as ultrahigh-pressure liquid chromatography (UHPLC) when the column backpressure exceeds 10000 psi (approximately 700 bar). Until recently, columns packed with sub-2-microm materials have generally fitted into two classes; either short (less than 5 cm) columns designed for use on traditional HPLC systems at pressures less than 5000 psi (350 bar), or capillary columns (inner diameters less than 100 microm). By using packing materials with diameters <2 microm to fabricate UHPLC columns, there is an increase in efficiency and a decrease in the analysis time that are directly proportional to the size of the packing material. In order to realize and exploit the increase in efficiency, however, the columns must maintain lengths typically associated with analytical columns (15-25 cm). We have packed 1 mm diameter, 150 mm in length columns with 1.5 microm packing material, and evaluated their performance in UHPLC. The pressure required to achieve optimum linear velocities in plots of plate height versus linear velocity was in the vicinity of 1104 bar (16000 psi). The 1.5 microm particle-packed column was compared with the more traditional 150 mm long analytical columns packed with 3 microm materials. This column showed an efficiency that was approximately twice that observed with the 3 microm packed column and a concomitant reduction in the analysis time, theoretically predicted.     

Two‐Dimensional Gas Chromatography. Concepts,Instrumentation, and Applications – Part 2: Comprehensive Two‐Dimensional Gas Chromatography

The writer of this review published in 1978 a three‐part article on two‐dimensional gas chromatography in the first three issues of this journal [1]. The review was written at a time when capillary column GC was still in its infancy. Commercial columns were (essentially) unavailable and sample introduction into capillary columns was done exclusively in the split mode. Two‐dimensional separations were explored in only a few laboratories. The limitations of capillary column technology made this exercise rather difficult. The introduction of fused silica capillary columns in the early eighties drastically changed the landscape in which gas chromatography was practiced. It took the chromatographic community just a few years to convert from packed columns to capillary columns. Instrumentation and accessories specifically designed for capillary column use came onto the market. This writer had great hopes that the revolution in capillary column GC would be mirrored in the development of instrumentation for Two‐Dimensional Gas Chromatography. This never materialized. On the contrary, tentative steps taken by a few manufacturers and suppliers of chromatographic equipment fizzled out. It was perhaps the introduction of relatively inexpensive and user friendly GC/MS instrumentation, in combination with nearly indestructible fused silica capillary columns that took away the incentive to develop commercially viable Two‐Dimensional Gas Chromatography. Much of the thinking went like this: why insist on good chromatography if mass spectrometry can do the job without the need of complete separation. Some progress in the further development of conventional Two‐Dimensional Gas Chromatography has certainly been made over the last 20 years but there has not been a great deal of excitement. Applications have also been relatively sparse and they are limited to just a few areas. Science does not remain static and chromatography is no exception. Progress in gas chromatography is driven by new technology and ideas. Substantial improvements in two‐dimensional GC were not forthcoming until Phillips and his research group introduced and implemented an entirely new form of Two‐Dimensional Gas Chromatography, called comprehensive GC×GC. This breakthrough occurred only in 1991 [2]. It does take some time before scientists change attitudes and habits. There is always a time lag between the introduction of new technology and its general acceptance. The public's attitude toward comprehensive Two‐Dimensional Gas Chromatography is probably no exception. The number of scientists who are actively pursuing this new branch of gas chromatography is still very small. It is often a single individual who carries the torch. J.B. Phillips' name is synonymous with comprehensive Two‐Dimensional Gas Chromatography. He is not only its inventor and proponent but his fertile mind has initiated research in other related areas. Sadly, he passed aware shortly before this review was written. This contribution is dedicated to his memory.     

Advances in sol-gel based columns for capillary electrochromatography: sol-gel open-tubular columns

The development of sol-gel open-tubular column technology in capillary electrochromatography (CEC) is reviewed. Sol-gel column technology offers a versatile means of creating organic-inorganic hybrid stationary phases. Sol-gel column technology provides a general approach to column fabrication for microseparation techniques including CEC, and is amenable to both open-tubular and monolithic columns. Direct chemical bonding of the stationary phase to the capillary inner walls provides enhanced thermal and solvent stability to sol-gel columns. Sol-gel stationary phases inherently possess higher surface area, and thus provide an effective one-step alternative to conventional open-tubular column technology. Sol-gel column technology is applicable to both silica-based and transition metal oxide-based hybrid stationary phases, and thus, provides a great opportunity to utilize advanced material properties of a wide range of nontraditional stationary phases to achieve enhanced selectivity in analytical microseparations. A wide variety of stationary phase ligands can be chemically immobilized on the capillary inner surface using a single-step sol-gel procedure. Sol-gel chemistry can be applied to design stationary phases with desired chromatographic characteristics, including the possibility of creating columns with either a positive or a negative charge on the stationary phase surface. This provides a new tool to control electroosmotic flow (EOF) in the column. Column efficiencies on the order of half a million theoretical plates per meter have been reported for sol-gel open-tubular CEC columns. The selectivity of sol-gel stationary phases can be easily fine-tuned by adjusting the composition of the coating sol solution. Open-tubular columns have significant advantages over their packed counterparts because of the simplicity in column making and hassle-free fritless operation. Open-tubular CEC columns possess low sample capacity and low detection sensitivity. Full utilization of the analytical potential of sol-gel open-tubular columns will require a concomitant development in the area of high-sensitivity detection technology.     

开管毛细管色谱柱的制备及其在蛋白质组学研究中的应用进展

近年来随着生命科学等领域的深入发展,人们对微量样本分离分析的需求越来越高,液相色谱系统的微量化受到了更多的关注。由于开管毛细管色谱柱具有较低的反向压力,可通过采用更长的色谱柱提高柱效,从而实现对复杂生物样本的高效分离,因而成为液相色谱柱新的发展方向。本文对开管毛细管色谱柱的制备方法及应用进展进行了综述。