Gas chromatography is a type of chromatography that uses a gaseous mobile phase to separate compounds. It works by partitioning molecules between the gas mobile phase and a liquid stationary phase coated on a solid support. The mixture is vaporized and carried through a column by an inert gas. As the compounds interact differently with the stationary phase, they elute from the column at different times, allowing separation. Key components include the carrier gas, sample injection port, coiled column, and detectors. It has advantages such as applicability to most compounds and sample preservation, while disadvantages include low sensitivity and susceptibility to temperature/flow fluctuations.

2. GAS CHROMATOGRAPHY

3. Chromatography
Definition:
• Chromatography is the separation of a mixture
of compounds (solutes) into separate
components

4. Presented By:
Masoom Shani

5. Phases
There are two phases of chromatography:
• Stationary phase.
• Mobile phase.

6. Stationary Phase
• “A phase, which becomes adsorbed on the filter
media or a surface, is called “stationary phase”.
• It may be a liquid or a solid.
• Examples :
• Silica gel
• Alumina
• Filter paper, etc.
are some important stationary phases

7. Mobile Phase
• “The phase, which passes over stationary
phase, is called “mobile phase”.
• It may be a liquid or a gas.
• It is also called “eluent.
Examples:
• Alcohol, water, ethanol, acetic acid, acetone
or gas etc. are some important mobile phases

8. Gas Chromatography
Definition:
• A type of chromatography, in which gaseous
mobile phase is used.

9. Principle
• Partition of molecules between gas (mobile
phase) and liquid which is coated on to a solid
support is used as stationary phase.
• The mixture of components to be separated is
converted to vapour and mixed with gaseous
mobile phase.

10. Components
• Carrier gas
- He (common), N2, H2, Argon
• Sample injection port
- micro syringe
• Columns
2-50 m coiled stainless steel/glass/Teflon
• Detectors
-Flame ionization (FID)
-Thermal conductivity (TCD)
-Electron capture (ECD)
-Nitrogen-phosphorus
-Flame photometric (FPD)
-Photo-ionization (PID)

11. Working
• It involves a sample being vaporized and
injected onto the head of the
chromatographic column. The sample is
transported through the column by the flow
of inert, gaseous mobile phase. The column
itself contains a liquid stationary phase which
is adsorbed onto the surface of an inert solid.

13. Types
• Two major types
• Gas-solid chromatography
(stationary phase: solid)
• Gas-liquid chromatography
(stationary phase: immobilized
liquid)

14. Advantages
 Applicable to most compounds.
1) Applicable to most compounds.
2) The sample is not destroyed and hence
used in preparative scale.
3) Simple
4) Easy to maintain
5) Inexpensive is good.
 The sample is not destroyed and hence
used in preparative scale.

15. Disadvantages
1) Low sensitivity.
2) Affected by fluctuations in temperature
and flow rate.
3) The response is only relative and not
absolute.
4) Biological samples cannot be analysed.