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How to realize gas-liquid chromatography separation in laboratory equipment operation

Apr 04, 2018

The gas-liquid chromatography stationary phase is a fixed liquid on the surface of the carrier. The sample gas is brought into the column by the laboratory equipped carrier gas, and when it is in contact with a certain liquid, each gas phase is dissolved into the fixed liquid.

As the laboratory equipment carrier gas is continuously introduced, the dissolved components are volatilized from the fixative solution, and the volatilized components are moved forward with the carrier gas and dissolved again by the fixative solution. As the carrier gas flows, the process of dissolution and volatilization is repeated.

Due to the difference in the nature of the components, the dissolving power of the fixative solutions is different. The components that are easily dissolved are difficult to evaporate. They move slowly in the lab equipment column and have a long residence time (ie, a long retention time). Conversely, components that are not easily dissolved, which evaporate quickly and move with the carrier gas. Fast, short stay in the laboratory equipment column.

After a certain time interval (the length of the column), the components with different properties are separated from each other.

The process of adsorption-desorption and dissolution-volatilization that occurs between the stationary phase and the mobile phase of matter is called the distribution process.

Obviously, the two components with the same distribution coefficient or distribution ratio, their peaks always overlap and cannot be separated; and the greater the difference between the partition coefficient or distribution ratio, the longer the corresponding peak distance and the slower the separation.

In general, for gas-solid chromatography, the first thing that comes out is the one with low adsorption capacity and large desorption capacity: For gas-liquid chromatography, the first one is the material with small solubility and high volatility. In general, substances with a small distribution coefficient come out first, followed by peaks with a large distribution coefficient.