Gas chromatography has been developed for decades. It is a mature and widely used method for the separation and analysis of complex mixtures. GC can analyze a wide range of samples, and its application fields include the petrochemical industry, environmental protection, food analysis, medicine, health, etc.
In 1903, the Russian botanist tswitt used a column filled with calcium carbonate and petroleum ether as the mobile phase to separate the different pigments in the green leaf extract into separate bands, which gave birth to chromatography.
The appearance of capillary gas chromatography in 1957 is an important milestone in gas chromatography. Compared with the traditional packing column, it has a new improvement in separation efficiency and analysis speed. In the development of capillary gas chromatography, the tube of capillary gas chromatography column has changed several times. The variety of capillary column increases rapidly with the development of chromatographic stationary phase. From the development of gas chromatography column, we can see that chromatographic workers make the chromatographic technology constantly updated and improved, and make gas chromatography develop into one of the quite perfect technologies in chromatography at present.
Gas Chromatography is also called GC column. Its core is the chromatographic column. There are many types of gas chromatographic columns, which can be classified according to the material and shape of the column, the size and length of the inner diameter of the column, the chemical properties of the stationary liquid, etc. The materials used for chromatographic column usually include glass, quartz glass, stainless steel, and polytetrafluoroethylene. The materials used, are called glass column, quartz glass column, stainless steel column, and polytetrafluoroethylene column respectively.
At present, glass column and quartz glass column are widely used in capillary chromatography, and the latter is the most widely used. After more than 20 years of continuous improvement and development, capillary chromatographic column has greatly improved its column efficiency, column life, repeatability, inertia and thermal stability.
Development of capillary gas chromatography and capillary column
The appearance of capillary gas chromatography is an important milestone in the development of gas chromatography. It improves the separation efficiency and analysis speed to a new level than the traditional packed column.
The concept of capillary gas chromatography was first put forward by Martin. He predicted that the total efficiency of chromatographic separation would be greatly improved if the column with very thin inner diameter was used.
Golay initially investigated the separation of air peaks with a polyethylene capillary and succeeded in the separation of air peaks with an inner diameter of 250 μ The inner wall of metal capillary was coated with a thin layer of polyethylene glycol stationary solution (1% dichloromethane solution w / V). The separation of capillary gas chromatography was realized for the first time by using thermal conductivity cell detector. The result obtained by him is about 7-8 times higher than that of the filled column at that time, which shows the advantages and potential of this new method.
At the international gas chromatography Symposium in 1957, Golay reported his research results, analyzed the factors affecting column efficiency theoretically for the first time, and realized Martin’s prediction.
At the second international gas chromatography Symposium in 1958, Golay put forward the kinetic theory of wall coated capillary column chromatography and showed the chromatograms of separating m-xylene, p-xylene and hexane isomers. For the first time, capillary column was used to solve the problem of isomer separation that was difficult to solve at that time.
In 1959, Scott successfully used nylon as the column material to produce capillary columns with different lengths and inner diameters. In the 1970s, they began to use glass materials to make capillary columns.
At the second international capillary report conference in 1979, dandeneau and zerenner reported the research of using fused silica, namely elastic quartz capillary column, as capillary, and the preparation of capillary has reached a new level since then. Because elastic quartz has good flexibility, is not easy to break, is easy to operate, has good inertia on the inner surface, weak adsorption on some polar and hydrogen bonded compounds and small tailing.
Therefore, in the late 1980s, quartz capillary column has gradually replaced glass capillary column and become the best capillary column material. Whether glass or quartz capillary column, in order to obtain high column efficiency in the coating process, the stationary liquid must form a uniform and complete solid liquid film on the inner surface of the column. Therefore, in order to make the stationary liquid on the glass or quartz column have good coating, various treatments must be carried out on the inner wall of the capillary, that is, to increase the critical surface tension on its surface, so as to improve its wettability.
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