The categorizes groups with Chromatography

  • November 21, 2020

Chromatography is a separation Process between two stages, stationary and mobile phase. Mixture to be examined is adsorbed in stationary phase and mobile phase is passed into it, eventually compounds of mix have separated based on rate of adsorption and solubility. Both are physical properties. Based on this, chromatography is categorized into two groups.

Adsorption chromatography:

  • Column Chromatography:

Normally, within this chromatography, a glass tube is full of adsorbent alumina or silica gel up-to one third of it is length. Then, it is saturated with selective solvent. Sometimes, column is full of slurry adsorbent + solvent. The column should have no space. This type of column is stated as ‘well packed column’. In this technique, less polar compound will be eluted first finally; more polar compound will come out.

  • Thin layer chromatography:

In TLC, a plate glass/plastic is coated with a thin layer of solid adsorbent. A little drop of mixture is seen near the bottom of plate. Then, plate is set in solvent chamber in this a way that only bottom part gets dipped into solvent mobile phase. This liquid gradually rises up to TLC. In this approach, separation is measured by RF value. Separated compounds move to various space, which can be expressed by retention factor RF worth. Compound of lower polarity will have greater RF worth than more polar ones.

Partition chromatography:

  • Paper chromatography:

Within this chromatogram, stationary phase is water adsorbed in newspaper and mobile phase is combinations of different organic solvent and water. Any fall of organic solvent on a filter paper becomes partitioned between water and solvent. Then, this paper is dipped into variety of solvent mixtures and chromatograms are developed. Ascending and descending, these two kinds of development generally occur. Like TLC, within this method too, separation is expressed by RF value. Compounds with higher RF value has lower polarity and vice versa.

  • Gas chromatography:

This is the most modern technique of chromatography. It is commonly used in analytical chemistry. In this method, sample vaporized without decomposition is injected into pillar. The sample is transferred through this column from the flow of mobile phase. Here, mobile phase is inert carrier gases Ex- He or nitrogen. Column is coated with different stationary phases. So, essentially, elements of Analyzed mix are partitioned between strong stationary phase and portable gas. Each compound elute in another time, which is called retention time. Compounds eluted at different retention period then get detected in various detectors. Finally, these are listed in a recorder and chromatograms are obtained.


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