The detector generates a voltage that isproportional to the amount of the substance. The signal from the detector is then displayed by a chartrecorder and/or fed into a computer.Modern gas chromatographs are connected to a computer which displays the peaks of all the substances in thesample. This is called the chromatogram.
It does interact less with the stationary phase, hence the retention time is shorter, but the quality of separation deteriorates.The trade-off is that the retention time increases proportionally to the column length. There is also a significant broadening of peaks observed, because of increased back diffusion inside the column.
Most detectors are relatively sensitive and do not need a lot of material
GAS CHROMATOGRAPH MAIN
WORKING PRINCIPLE OF GC
PROCEDURE OF GC
FACTORS AFFECTING GC
•Greek word “CHROMA” and
•Process of separation and
analyzation of complex mixture
It works on the basis of rate at
which the types of components
flow. As the mixture of various
components enter the
chromatograph we will observe
that the different components
of a mixture move/flow at
different rate. This different
rate of flowing is responsible for
Gas chromatography is separation
Gas chromatography is
a chromatographic technique that can
be used to separate volatile organic
Gas Chromatography consists of
GAS CHROMATOGRAPH MAIN
This is the mobile phase and
should be inert gas(he, ar etc)
The injection port consist of
rubber septum through which a
syringe needle is inserted to
inject the sample.
Column is the most important
component where separation takes
Oven is also an important
component in which column is
Detector is to indicate the
presence and measure the amount
of component eluted out from the
The mixture of components
which is to be analyzed.
WORKING PRINCIPLE OF
It works on the principle that the
organic compounds are separated due
to differences in their partitioning
behavior between Mobile phase and
The mobile phase is comprised of
The stationary phase consists of
GC Sample is injected in column.
Oven heats the system to
vaporize the sample and speed
its passage through the column.
The different components of
the sample will be separated by
the column because each of the
components “sticks” to the liquid
coating that on the column
When a substance leaves the
column, it is sensed by a detector.
The detector generates the
voltage that is proportional to the
amount of the substance.
Temperature: T he higher the
temperature, the more of the
compound is in the gas phase.
Carrier gas flow: If the carrier
gas flow is high, the molecules do not
have a chance to interact with the
Column length: The longer the
column is the better the separation
Amount of material injected: The
injection of too much sample causes
Conclusion: High temperatures and
high flow rates decrease the retention
time, but also deteriorate the quality of