CHROMATOGRAPHY-TYPES

DIFFERENT TYPES OF CHROMATOGRAPHY

Basically the chromatography procedures are classified into two types:

(a) COLUMN CHROMATOGRAPHY: in column chromatography The stationary phase is located in a narrow pipe and the mobile phase is enforced through the pipe under pressure or by gravity.

COLUMN-CHROMATOGRAPHY

(b) PLANAR CHROMATOGRAPHY: In planar chromatography the stationary phase is supported on a flat plate or in the pores of a paper. The mobile phase moves through the stationary phase by Capillary action or under the influence of gravity.

planar-chromatography

Based on the type of the stationary phase  used in chromatography  the chromatography is classified into following types.

(1)  GAS CHROMATOGRAPHY (GC): The specific method may be gas - liquid (GLC) or gas - solid. In GLC, liquid is adsorbed or bond to a solid surface. There exists an equilibrium between gas or liquid. In gas-solid system solid is the stationary phase and the equilibrium is due to adsorption.

(2) LIQUID CHROMATOGRAPHY (LC): There are liquid-liquid (partition), liquid - solid (adsorption), ion exchange methods.

(3)SUPER CRITICAL FLUID CHROMATOGRAPHY (SFC): In this type superficial fluid is the mobile phase.

Chromatography procedure was first discovered by M. Tswette in 1903 to isolate the green pigment of green plant leaves. The property of differential adsorption of the component on a stationary support is applied in this procedure. When the mixture is poured down along column of packed adsorbing material the complex with greatest affinity to the adsorbent will be adsorbed first. Compounds with less affinity will accumulate below the first successively in the decreasing order of ease of being adsorbed.

This method is now known as "ADSORPTION CHROMATOGRAPHY" Depending upon the various physical properties involved in the separation procedure, different names have been given to this procedure. Some of them are

(1)   Column Chromatography

(2)   Adsorption Chromatography

(3)   Paper Chromatography

(4)   Two Dimensional Paper Chromatography

(5)   Thin Layer Chromatography

(6)   Ion Exchange or Displacement Chromatography

(7)   Paper Electrophoresis or Zone Electrophoresis.