This document compares gas chromatography (GC) and high performance liquid chromatography (HPLC). GC uses a gas mobile phase and separates compounds based on volatility, while HPLC uses a liquid mobile phase under high pressure and separates compounds based on interactions with the stationary phase. Some key differences discussed are that GC uses simpler, less expensive equipment than HPLC but can only analyze more volatile compounds, whereas HPLC can analyze a wider range of compounds including thermolabile ones. Both techniques have different instrumentation requirements and a variety of detectors can be used for analysis.

1. DERIVATIZATION OF GAS CHROMATOGRAPHY
&
COMPARISION OF GAS CHROMATOGRAPHY & HPLC
GUDIED BY:
Mr. UTTAM PRASAD PANIGRAHY
PRESENTED BY:
M.Srilatha
Pharmaceutics

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22. COMPARISION OF GC&HPLC

GAS CHROMATOGRAPHY
 In this technique a stream of
carrier gas that act as mobile
phase is passed over a fixed
stationary phase placed inside
the column.
 Principle:-
GLC=Partition chromatography.
Gsc=Adsorption
chromatography
HIGH PERFORMANE
LIQUID
CHRROMATOGRAPHY
 In this technique a liquid
mobile phase is pumped
at a high pressure
through a suitably
modified column that
acts as a stationary phase.
 Principle:-
separation in HPLC is
adsorption.

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 Depending upon the nature
of stationary phase used.
1) Gs-liquid chromatography:
 Mobile phase-Gas
 Stationary phase-Thin layer
of non-volatile liquid or a
polymer coated innert solid
 Ex;Porous polymer, sand
glass beads.
2)Gas-solid chromatography:-
Mobile phase-Gas
Stationary phase-solid
adsorbent
Ex; silicon rubber,poly
ethylene glycol
 Techniques of HPLC are
classified based on
I. Modes of chromatography
II. Normal phase mode:-
Mobile phase-Non polar-
Ex; hydrocarbon solvent alcohols
. Stationary phase-silica gel
3)Reverse phase mode:-
Mobile phase-polar-
Ex; methanol with water aqueous
buffer
Stationary phase-non polar-
Ex; alcohol chlorinated, solvents.

24. 2)HPLC-principle of separation:-
1. Adsorption chromatography:- Adsorption
2. Ion- exchange chromatography:-Reversible

exchange of ions.
3. Gel permeation chromatography:-Molecular filtration
4. Affinity chromatography:-Affinity of analytic towards
stationary phase
3)Elution technique:- Isocratic separation
Gradient separation
4)Scale of operation:- Analytical HPLC
Pre-operative HPLC
5)Type of analyse:- Qualitative analysis
Quantitative analysis

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 The concept of gas
chromatography between
1941&’1943
 Instruments used are
simple, less expensive.
 Equipment cost is 8 lacks
above
 pore size-
 Gaseous and volatile
compounds can be easily
separated and analysed
 The concept of the HPLC
between 1967&’1969
 HPLC columns are
expensive&eqiupment
cost is high.
 Equipment cost is 15-
20lacks above
 Pore size-3-10μm
 Gaseous and volatile
compounds cannot be
easily separated and
analysed

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 Thermo stable compounds
can be analysed
 Preparation of mobile phase
is easy. Ex;H2gas
 Mobile phase cannot be
recovered
 It requires temperature
programming.Ex;Linearmod
e
 Samples need to be heated
at elevated temperatures. If
it is not in the gaseous state
 Ex;Thermostable
 Thermo labile compounds
can be easily separated and
analysed
 Preparation of sample and
solvent is laborious& time
consuming process.
 Mobile phase can be
recovered
 Temperature. programming
is not essential
 Sample treatment is not
required when aqueous or
non aqueous samples are to
be analysed

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 Instrumentation
includes:-
a) Gas supply unit
b) Sampling unit
c) Columns units
d) Injection device
e) Detectors
f) Recorders
 Precolumn is not
required.
 Instrumentation
includes:-
a) Solvent delivery system
b) Injection
c) Columns
d) Analytical columns
e) Solvent degassing
gradient controller
f) Detector
g) Recorders
 A pre column is essential
that increases the
efficiency of
chromatographic
separation.
 Ex; Guard columns

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 Glass columns are most
commonly used because
they can withstand
higher temperature
 Sampleunit,column&dete
ctor needs an oven to
maintain higher
temperature
 Column length few
centimetres to several
hundred meters
 Column used-packed
columns
 Capillary &open tubular
 Analytical& preparative
 Stainless steel columns
are commonly used
because they can
withstand high pressure.
 Only column unit needs
an oven
 Column length 25cm-
100cm
 Columns used-conventional
columns
Micro bore columns

29. Detectors used are 2 types-
 A. Bulk property:-
Refractive indexdectors
Conductivity detectors
B. Solute property:-
UV-visible detector
Fluorescence detectors
Electro chemical detectors
A. Concentration dependent:-
 Thermal conductivity detector
 Electron capture detector
 Argon ionization detector
B. Mass flow dependent
 Nitrogen phosphorous
detector
 Flame photometric detectors

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