What is the separation mechanism of the chromatographic column?

Date:2021-11-11 16:27:06 Thursday

Summary:　　 Chromatography column is a chromatographic technique used to improve the retention behavior of strongly polar substances that are poorly retained in reversed-phase chromatography. It achieves this goal by using a strong polar immobility and combin......

　　 Chromatography column is a chromatographic technique used to improve the retention behavior of strongly polar substances that are poorly retained in reversed-phase chromatography. It achieves this goal by using a strong polar immobility and combining a mobile phase composed of a high proportion of organic phase/low proportion of aqueous phase. Such a mobile phase composition is particularly beneficial to improve the sensitivity of electrospray ionization mass spectrometry.
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　　 Column separation mechanism
The separation mechanism of is still controversial at present, mainly including the following three aspects:
　　 (1) Distribution mechanism
　　 (2) ion exchange
　　 (3) Dipole-dipole interaction. More experimental phenomena indicate that the retention mechanism of the chromatographic column includes multiple secondary effects such as hydrogen bonding, dipole, and electrostatic, which are difficult to distinguish.
　　 The main factors affecting the retention of the chromatographic column
　　 It is generally believed that the retention behavior of a chromatographic column is affected by many parameters, such as the functional group of the stationary phase, the content of organic modifiers, the flow rate, the column temperature, the pH value of the mobile phase buffer system, and the type and concentration of buffer salts.
"The main factor that affects the retention behavior of the sample on the stationary phase is the ratio of the organic phase in the mobile phase. For example, an increase in the content of acetonitrile will significantly increase the retention factor of the sample. In the column separation mode, the solvent elution ability is from weak to strong: acetone<acetonitrile<isopropanol<ethanol<methanol<water, and water in the mobile phase is a strong elution solvent. Generally, acetonitrile-water system is used as the mobile phase, and the proportion of the water phase is 5%-40% to ensure its significant hydrophilic effect. Replace the aqueous phase in the mobile phase with methanol, ethanol, or isopropanol. As the polarity of the mobile phase decreases, the retention of the analyte on the chromatographic column will increase.
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