ARUNKUMAR.K breif explanation with 4 chromatographical methods RVS COLLEGE OF PHARMACEUTICAL SCIENCES

1. CHROMATOGRPHY;
It is a technique used to separate and identify the
components of the mixture .
TYPES OF CHROMATOGRAPHY;
 Paper chromatography
Column chromatography
Thin layer chromatography
High performance liquid chromatography
Ion exchange

2. Gas chromatography
Affinity chromatography
Gel permeation
Dye ligand chromatography

3. GAS CHROMATOGRAPHY
In gas chromatography gas is used as mobile phase
solid or liquid is used as stationary phase.
Two types of gas chromatography are there:
 GSC- Gas solid chromatography(absorption),
GLC - Gas liquid chromatography(partition).
GSC is not widely used because limited number of
stationary phase is available
Hydrogen,Helium,Nitrogen and Argon are used as mobile
phase.

5. SEPERATION PRINCIPLE
The principle separation in
GLC is partition.
Gas is used as mobile
phase.
Liquid which is coated on a
solid supports used as
stationary phase.
Components are separated
according to partition co
efficient.

6. CRITERIA FOR COMPONENTS TO BE
ANALYSED BY GC;
o Volatility
oThermostability
REQUIREMENTS;
Carrier gas
Flow regulator
Flow meter
Injection devices
Columns
Temperature control
devices
Detectors
Recorders&Integrations

7. CARRIER GAS;
Carrier gas determining the efficiency of
chromatographic separation.
Hydrogen,Helium,Nitrogen&Argon are commonly
used as carrier gases.
REQUIREMENTS OF CARRIER GAS;
Inertness ,
Suitable to the Detector used,
High purity,
Easily available,
Cheap,
Less risk of explosion of fire.

8. FLOW REGULATORS;
Flow regulators are used to deliver the gas with uniform
pressure/flow rate.
FLOW METERS;
Flow meters are used to measure the flow rate of
carrier gas.
They are Rota meter and Soap bubble flow meter.

9. INJECTION DEVICES;
Gases are introduced into the column by valve
devices.
Liquids can be injected through loop (or) septum
devices.
The septum is made up of silicon rubber.
COLUMNS;
Column is one of the important part of Gas
chromatography.
Which decides the efficiency of the separation.
These are made up of Glass/Stainless steal.

10. CLASSIFICATION OF COLUMNS;
Analytical column,
Preparative column,
Packed column,
Open tubular column/Capillary column/Goly column,
Support coated open tubular column(SCOT).

11. TEMPERATURE CONTROL
DEVICES;
PRE HEATERS:
Used to convert the samples into it’s vapour form and
mix them with mobile phase
THERMOSTATICALLY CONTROOLED OVEN:
Solubility of solute depends upon temperature ,
temperature maintanance in a column is highly essential
for efficient separation .

12. OPERATIONS
TWO TYPES OF OPERATIONS;
Iso thermal
programming.
Linear
programming

13. DETECTORS;
Detectors are considerd as heart of the apparatus. It can
detect the difference between a pure carrier gas and a
eluted component.
THE RIQUIREMENT OF AN IDEAL
DETECTOR;
•Applicability to wide range of sample,
•High sensitivity,
•Rapidity of response,
•Linearity,
•Non destructive,
•Inexpensive,
•Simple and easy to maintain.

14. TYPES OF DETECTORS;
There are four types of detectors are there , they are:
o Thermal conductivity detector,
o Flam ionisation detector,
o Argon ionisation detector,
o Electron capture detector.

15. THERMAL CONDUCTIVITY DETECTOR
Difference between carrier gas
and analyte . Temperature at
constant electric power depends on
the surrounding gas. The electric
resistance of the element depends
on the thermal conductivity of the
gas. Operating principle replies of
the gaseous mixture. The thermal
conductivity affects the resistance
of the thermistor as a function of
temperature

16. ADVANTAGES;
Applicable to most compounds
Linearity is good ,
Sample is not destroyed ,
Easy to maintain,
In ex[pensive.
DIS ADVANTAGES;
Low sensitivity
Affected by fluctuations
Response is only relative not absolute
Biological sample can not be analysed.

17. FLAME IONISATION DETECTOR;
The flame ionisation detector is
the most sensitive gas
chromatographic detector for
hydrocarbons such as
butane/hexane with a linear range
for 6/7 orders of magnitude and
limits of detection in the low
picogram (or) femtogram range.
The FID is the most widely and
successfully used gas
chromatographic and many
carbon containing compounds

18. ADVANTAGES;
Flame ionisation detectors are relatively inexpensive to
aquire and operative.
It requires low maintenance .
FID’s are relatively resistance of misuse.
It measure organic substance concentration at very low
and very high levels.
DIS ADVANTAGES;
It cannot detect inorganic substance and highly
oxygenated.
It oxidise all oxydizable compounds that pass through it.

19. ARGON IONISATION DETECTOR;
For argon ionisation detector
Argon gas is used as the carrier
gas. It consists of two electrodes
placed parallel to each other. A
potential difference is applied
across them. The effluent from
the column is allowed to enter the
ionisation detector.
This detector is sensitive to
most of the organic and
insensitive to H2O,O2,CO2 and
Hydrogen

20. ADVANTAGES;
It sensitive to most of the organic and inorganic
compounds.
It has a high linear dynamic range.

21. ELECTRON CAPTURE DETECTOR;
This detector operates similar
to proportional counter used for
X ray measurement. The
electron capture detector is
highly sensitive molecule
containing electro magnetive
functional groups like
Halogens, Peroxides, Nitro
groups. It insensitive to the
functional group like amines,
alcohols, and hydrocarbons.
Hence it is a powerful tool in
the determination of
chlorinated insecticides.

22. ADVANTAGES;
Highly sensitive
Non destructive to the sample
DIS ADVANTAGES;
Highly non linear response.

23. APPLICATIONS OF GAS CHROMATOGRAPHY;
Separation and identification of lipids, carbohydrates and
proteins.
Separation and identification of amino acids in urine by
GC-MS for diagnostic purpose.
Analysis of pesticides in soil, water, food.
Alcohol in blood.
Analyse the contents of chemical products.
Pharmaceutical and drug analysis.
Clinical toxicology.
Geochemical research.