Capillary Gas chromatography (GC) is a simple insulating device with a narrow tube with an insulation coating in its interior side.
Overall there are three types of capillary Gas cylinder available in the market which can be used for this purpose. They generally have tube -like structure and are differentiated on the basis of their coating; they are wall coated, support coated and porous coated.
- Wall coated or WCOT are open tube chambers.
- Support coated or SCOT are open coated tubes having liquid in it.
- Porous coated or PLOT are open coated tubes having poros absorbent.
Characteristics of capillary Gas chromatography are:
- They are used in GC.
- They can provide high resolution
- They are capable of low sample capillary.
- They have shorter analysis time.
- Flow rate goes to 10-20ml/min in packed chambers
- Flow rate goes to 0.5- 2ml/min in capillary.
What is chromatography?
Gas Chromatography Column is just a simple process of sorting compounds which are generated due to the striking of solid surface to mobile surface. For instance if you take water or alcohol and throw it on a paper it will move on it. But what you will observe is that the rate at which it is moving directly depends on how heavy or sticky are the compounds of the flowing substance. If it is heavy it will flow slowly or sticky it will flow slowly but if they are lighter then the situation will definitely go vice versa.
This situation can differ in gases as Gases are the mobile substance and can move where they want.
How does the movement take place inside the capillary column?
In the capillary column the gases move inside the column due to the presence of high pressure between the inlet and Outlet.
However the speed of this can totally vary as it is based on how quickly and speedy they have traveled as mentioned above the rate at which it is moving directly depends on how heavy or sticky are the compounds of the flowing substance. If it is heavy it will flow slowly or sticky it will flow slowly but if they are lighter then the situation will definitely go vice versa.
One thing which needs to be noted according to experts is that it doesn’t contain coated particles and if we are trying to do so then it can result in forever blockages. Coating is always done into the interior side of the chamber
What are the dimensions of capillary?
Capillary columns are narrow tubes which can vary from 12m to 60m in length and can have internal variations as well.
But in general their dimensions are from 30m -60m in length x 0.24 um ID x 0.25 um film thickness.
However, the ideal thickness for capillary is from 0.1 mm to 0.53 mm. These columns give much seperate as company to packed ones.
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