If you boil a liquid of mixture of components of same group then what happened? The volume of mixture is decreasing because of some components are vaporizing.
Which type of components are vaporizing fast?
The answer is lower molecular weight components are vaporizing fast.
We need to identify them.
GC-MS work like this way.
Firstly it injects a very small amount of liquid mixture then make it vapour. There is a continuous innert gas flow for this the vaporized gas blow with it and ionized in ion source and detected, calculated.
This is a nice technology. Science has become more advanced with this invention. Life science, textile also other sectors have its intensive use.