COLUMN CHROMATOGRAPHY  

Principle 

Column chromatography is a laboratory technique used to separate mixtures of compounds. It works by application of the absorbance of different rates at which the components of a mixture travel through a column packed with a stationary phase when driven by a solvent (the mobile phase).

Procedure 

  1. Prepare the column. Fill a glass column with a suitable stationary phase, such as silica gel or alumina. Pack the stationary phase tightly to prevent channeling, but not so tightly that it restricts the flow of solvent.
  2. Pre-elute the column. Add a small amount of solvent to the column and allow it to flow through. This will help to saturate the stationary phase and remove any air bubbles.
  3. Load the sample onto the column. The sample can be loaded onto the column in a variety of ways, but the most common method is to dissolve the sample in a small amount of solvent and add it to the top of the column using a pipette.
  4. Elute the column. Add a solvent to the column and allow it to flow through. The solvent will dissolve the compounds in the sample and carry them down the column. The different compounds will move through the column at different rates, depending on their affinity for the stationary phase. The compounds that are less strongly attracted to the stationary phase will move through the column more quickly.
  5. Collect the fractions. As the solvent flows through the column, it will elute the different compounds in the sample. The compounds can be collected in fractions by placing a collection vessel below the column and opening the stopcock when the desired compound is eluting.

APPLICATIONS 

(i)              Used to isolate Active ingredients.

(ii)            Very helpful for the separation of compound mixtures

(iii)          Used to determine drug estimation from drug formulations

(iv)           Used to remove impurities

Application of Gas Chromatography

Gas chromatography is a technique for separating and analyzing volatile compounds in a gas phase. Some of the applications of gas chromatography are:

  • Environmental analysis: Gas chromatography can be used to measure the levels of air pollutants, pesticides, and other contaminants in water, soil, and air samples.
  • Clinical analysis: Gas chromatography can be used to detect and quantify drugs, alcohol, and other substances in blood and urine samples.
  • Forensic analysis: Gas chromatography can be used to identify the presence of explosives, arson accelerants, and other trace evidence in crime scenes.
  • Consumer products: Gas chromatography can be used to analyze the volatile organic compounds in spices, fragrances, whiskey, and other products.
  • Petrochemical and chemical industry: Gas chromatography can be used to monitor the purity of solvents, the composition of gasoline, and the quality of chemicals in various industries

Application of TLC

It is based on the principle of adsorption, which is the attraction of molecules to a surface.

TLC uses a thin layer of stationary phase coated on a plate (0.03 mm thick). The mobile phase is then applied to the plate and allowed to flow by capillary action.

(i)              The qualitative testing for various medicines (such as Sedatives, Local anaesthetics, antihistaminic, analgesics) is done by TLC.

(ii)            Used to identify natural products like essential oils, volatile oils, fixed oils, waxes, alkaloids etc.

(iii)          Isolation of biochemical metabolites from blood plasma, urine.

(iv)           Septation of multicomponent pharmaceutical formulations.

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