Advantages and disadvantages of chromatographic tray theory and chromatographic rate theory in chromatographic research

Tray theory is based on thermodynamic approximation theory. Although it can well explain the peak type and peak height of chromatographic peaks and objectively evaluate the column efficiency of chromatographic columns, it can not well explain some phenomena related to kinetic processes.

Such as the deformation of chromatographic peak shape, the relationship between theoretical plate number and mobile phase velocity, etc. The rate theory is considered from the perspective of dynamics and can be complementary to the tray theory. So these two theories are very useful in the field of chromatography research.

The U-shaped curve equation of chromatographic flow is derived from the tray theory, which successfully explains the shape of the outflow curve and the position of the maximum concentration point, and can evaluate the column efficiency of the chromatographic column, thus indicating that the peak height of normal peak can be used for quantitative analysis, and improving the column efficiency and sensitivity of chromatographic analysis.

Extended data:

In the packed chromatographic column, when the gas stream hits the packing particles, it will constantly change direction, thus making the sample components form a chaotic vortex flow in the gas phase. Therefore, molecules of the same component have different path lengths, so their residence time in the chromatographic column is also different. They reach the end of the chromatographic column within a certain time interval, so the chromatographic peak expands due to diffusion.

This kind of diffusion is called eddy diffusion, and a is called eddy diffusion term, which is related to the average particle size of filler and the uniformity of filler.

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