Difference between solvent extraction and chromatography | Solvent extraction | Chromatography

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By chempeers.com

Difference between solvent extraction and chromatography

Solvent Extraction:

  • This process was used before the concept of chromatography.
  • This is the separation technique in which the solvent layers are immiscible with each other.
  • The extraction of solute is based upon the solubility of solute between two immiscible liquids which are usually water (polar) and organic solvent (non-polar).
  • Mixture of solutes cannot be easily separated by this method of separation. We have to provide much specific conditions to separate one solute such as by use of masking agent etc. but this method is also not much useful.
  • This process is called ancestor of chromatography. Because concept of chromatography was originated through this process.
  • We have to use a lot of solvent to separate solute and its disposal problems are also present because the organic solvents may be harmful for environment.
  • There is a very less chance that two immiscible liquids should be present and solute must move in large quantity from one phase to another. So, this process is limited.
  • This is not so much economic process because we have to use large quantity of solvents in this.
  • This is not a time taking process because equilibrium between two immiscible is formed earlier.
  • If we have found two immiscible solvents and solute can also be separated through them but we are still not much assuring that we would get a good quantity of solute after extraction because this process depends upon distribution ratio D and distribution coefficient KD of solute separated. This also depends that solute if a weaker acid is not present in dissociated form. If it is present in dissociated form, then it could not be separated easily.
  • There are not so much types of solvent extraction that if one type does not match to our desire then we could use another type.
  • Charged solute particles such as (cations or anions) could not be separated by this easily. And if we use a chelating group to neutralize charge them it would not be economic process.
  • This process is usually used in labs but not in industry usually.
  • This process can be done on micro-level.

Chromatography:

  • This process was introduced after solvent extraction.
  • This is separation technique in which solvent layers are miscible with each other.
  • In this solute mixture moves with mobile phase in stationary phase and each solute moves with varying interactions with stationary phase. Mobile phase and stationary phase are miscible with each other here.
  • Mixture of solutes can be easily separated by this procedure because every solute has different interactions with stationary phase.
  • This process is called descendent of solvent extraction.
  • We have not to be use much quantity of solvent to separate the mixture of solutes.
  • There are a lot of such miscible solvents present through which mixture of solutes can be separated easily.
  • This is economic process because small amount of solvents is used to separate a good quantity of solute.
  • This process may be time taking because of use of two miscible liquids. Time also depends upon number of theoretical plates and plate length but this also increases resolution of mixture of solutes separated.
  • In this there is not any concept of distribution ratio or coefficient. Every solute can be separated easily even if it is present in dissociated form.
  • Many types of chromatography are present through which we could separate our solute mixture.
  • By using stationary phase of opposite charge than that of solute, charged solutes could also be separated through this procedure easily.
  • This process is usually use in both laboratory and industry.
  • This process cannot be done on micro-level.

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