The development of gas chromatography technology has a history of several decades. It is a fairly 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 petrochemical, environmental protection, food analysis, medicine and health, etc.
In 1903, the Russian botanist Tswett used a column filled with calcium carbonate and petroleum ether as the mobile phase to separate different pigments in the green leaf extract into separate bands, and chromatography was born.
The appearance of capillary gas chromatography in 1957 was another important milestone in gas chromatography. Compared with traditional packed columns, it has new improvements in separation efficiency and analysis speed. During the development of capillary gas chromatography, the tube material of capillary gas chromatography column has changed several times. The variety of capillary columns increases rapidly with the development of chromatographic stationary phases. From the development history of gas chromatographic columns, we can see that chromatographic workers are constantly updating and improving chromatographic technology, making gas chromatography one of the most complete technologies in current chromatography.
Gas chromatography (referred to as GC) is also known as gas chromatography, gas chromatography. At its heart is the column.
There are many types of gas chromatography columns, which can be classified according to the material, shape, size and length of the inner diameter of the column, and the chemical properties of the stationary liquid. The materials used for chromatographic columns are usually glass, quartz glass, stainless steel and polytetrafluoroethylene, etc., which are called glass columns, quartz glass columns, stainless steel columns and polytetrafluoroethylene columns, etc. according to the materials used.
Currently, glass columns and quartz glass columns are commonly used in capillary chromatography, with the latter being the most widely used. After more than 20 years of continuous improvement and development of capillary chromatographic columns, its column efficiency, column life, repeatability, inertness and thermal stability have been greatly improved and improved.
Development of Capillary Gas Chromatography and Capillary Columns
The emergence of capillary gas chromatography is an important milestone in the development of gas chromatography. Compared with traditional packed columns, it has improved a new level in terms of separation efficiency and analysis speed.
The concept of capillary gas chromatography was first proposed by Martin, who predicted that the overall efficiency of chromatographic separation would be greatly improved if a column with a very thin inner diameter was used.
Golay initially investigated the separation of air peaks with a polyethylene capillary, and successfully coated the inner wall of a metal capillary with an inner diameter of 250 μm with a thin layer of polyethylene glycol fixative (1% dichloromethane solution w/ v), Separation by capillary gas chromatography was achieved for the first time using a thermal conductivity cell detector. The results obtained by him are about 7-8 times higher than the column efficiency of the packed column at that time, showing the advantages and potential of this new method.
Golay reported his research results at the International Gas Chromatography Symposium in 1957, and for the first time theoretically analyzed the factors affecting column efficiency, realizing Martin’s prediction.
At the Second International Gas Chromatography Symposium in 1958, Golay proposed the kinetic theory of wall-coated capillary column chromatography, and showed the chromatograms for the separation of m-, p-xylene and hexane isomers. For the first time, capillary columns were used Solved the separation problem of isomers which was difficult to solve at that time.
In 1959, Scott successfully used nylon as the column material to produce capillary columns of different lengths and different inner diameters. In the 1970s, glass materials were used to make capillary columns.
In 1979, at the Second International Capillary Report Conference, Dandeneau and Zerenner reported the research on using fused silica, that is, elastic quartz capillary column, as a capillary. Since then, the preparation of capillary has reached a new level. Because elastic quartz has good flexibility, is not easy to break, is easy to operate, has good inner surface inertness, has weak adsorption to some polar and hydrogen bond compounds, and has small tailing.
Therefore, in the late 1980s, the quartz capillary column has gradually replaced the glass capillary column and has become the best capillary column material today. Regardless of glass or quartz capillary column, in order to obtain high column efficiency during the coating process, the fixative must form a uniform, complete and firm liquid film on the inner surface of the column. Therefore, in order to make the fixative on the glass or quartz column have a good coating, various treatments must be carried out on the inner wall of the capillary, that is, to increase the critical surface tension of its surface in order to improve its wettability.