Tuesday, June 2, 2020

Factors affecting column chromatography

Column chromatography is one of the most effective methods for isolating and purifying of solids and liquid compounds. It is a solid-liquid method in which the mobile phase is a liquid and the stationary phase is a solid. The basic principle of column chromatography is adsorption. The sample mixture is placed over the column and dissolved in the solvent or mobile phase and travels through the stationary phase. Based on their relative affinities of analytes are separated into a different fraction. The separation process or mobile phase is optimized using thin-layer chromatography (TLC) before performing column chromatography. There are 4 types of column chromatography are available such as partition chromatography, adsorption chromatography, ion-exchange chromatography, and gel chromatography.
The separation, resolution, retention time, and efficiency of column chromatography is dependent on different factors, some of the key factors include.
The polarity of the mobile phase: The polarity of the mobile phase is related to the resolution, Rf value, and separation of analytes, the drastic variations in the polarity of the solvent can affect the result of column chromatography.
Nature of the solvent: The flow rate of the solvent can be affected by its viscosity. Thus, the solvent has a low viscosity that is efficient compared to a more viscous solvent.
Quality of solvents: High-quality solvents can give much better reproducibility than low-quality solvents.
Solvents selection: The solvents or mobile phase used must be compatible with the matrix; in this case, the TLC is a very effective way to optimize the mobile phase.
Flow rate: Changes in the flow rate between the processes can affect column efficiency; hence the components need to be isolated with a suitable flow rate.
Packing of the column: Column packing is an essential aspect of resolution, proper packing of columns is very crucial to obtain better performance. 
Column dimension: Chromatographers use different dimensions of a column, it depends on the process and usage. Length, height, and width of columns are important factors for the separation of molecules, hence appropriate column dimensions need to be selected.
The particle size of the adsorbent: The movement of the adsorbent is dependable on their surface area, for enhancing the surface area of adsorbent, the particle size can be decreased, and therefore the activity of the adsorbent increases.
Pressure: The increase or decrease of pressure between the separation can affect the results.
The temperature: Temperature is also an important factor in chromatographic separation because variations in temperature can affect the separation process and in some cases, it degrades the sample.

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