GAS CHROMATOGRAPHY, complete details

1. A N A LY T I C A L
P R E S E N T A T I O N
TOPIC − GAS CHROMATOGRAPHY
INTRODUCTION.
SAMPLE INJECTION SYSTEMS
COLUMN TYPES
DETECTORS
APPLICATION
Portfolio
Designed

2. Process of separating
component(s) from
crude by using mobile
phase
PRINCIPLE
Partition (Partition coefficient)
GAS CHROMATOGRAPHY

3. INSTRUMENTATION
He,N2 ,H2, Argon
Carrier Gas−micro syringe.
Sample Injection Columns

4. It splits the volume of sample stream
into two unequal flows by means of
needle valve, and allow the smaller
flow to pass on to the columns and
the bigger part is allowed to be vented
to the atmosphere
Split Injections :
 They allow all of the sample to
pass through the column for
loading
 Dilute to avoid overloading
Split less Injections :
SAMPLE INJECTION SYSTEMS

5. ON COLUMN INJECTION
A liquid sample is
introduced
directly into the column
with a thin injection
needle

6. AUTOMATIC INJECTORS
The solid sample are
introduced as a solution
in a sealed ampoule ,
crushed in gas stream
with help of plunger and
sample gets vaporized
and flows to column

7.  In GLC, they are densely packed,
with finely divided, inert , solid
support material coated with
liquid stationary phase.
 In GSC , with adsorbents or
porous polymers.
 Length- 1.5-10m
 Internal diameter- 2-4mm
COLUMN TYPES
Packed column Capillary column
Length ranges from
10-100m
Inner diameter-0.1-0.5mm

8.  PLOT columns contain a porous
layer of a solid adsorbent such
as alumina, molecular sieves, or
Porapak
 PLOT columns are well suited
for the analysis of light, fixed
gases, and other volatile
compounds. The typical
structure of a porous layer open
tubular column
POROUS LAYER OPEN TUBULAR
COLUMN

9.  In WCOT columns, the wall is
directly coated with the
stationary-phase layer at a
film thickness of 0.05–3 μm
 A typical wall-coated open
tubular column.
COLUMN TYPES
Wall-Coated Open Tub
ular
Column
Support-Coated Op
en
Tubular Column
These columns contain an
adsorbed layer of a very fine
solid support (such as Celite)
coated with the liquid phase
It can hold more liquid phase
and have a higher sample
capacity than the thin films
of early wall-coated open
tubular (WCOT) columns
had

10.  The fused silica tubes have much
thinner walls than glass capillary
columns, and are strengthened by
the polyimide coating
 These columns are flexible and can
be wound into coils
 They offer the advantages of
physical strength, flexibility, and low
reactivity
FUSED SILICA OPEN TUBULAR COLUMN

11.  Commonly used support
material in solid phase are:
diatomaceous earth or
kieselguhr, glass beads,
porous polymers, sand
etc.
COLUMN TYPES
Support material Liquid
It should be non volatile
Should have high decomposition
temperature
Should be chemically inert.
Should posses low vapor
pressure at column temperature
Should be chemically and
structurally similar to that of the
solute.

12. DETECTORS
The ideal detector for GC has the following
characteristics:
 Adequate sensitivity
 Good stability and reproducibility
 A linear response that extends over several orders
of magnitude
 A temperature range from room temperature to at
least 400°C
 A short response time independent of flow rate
 High reliability and ease of use
 The detector should be foolproof in the hands of
inexperienced operators
 It should be highly predictable and selective
response toward one or more classes of solutes
 The detector should be nondestructive

13. THERMIONIC DETECTORS
 The thermionic detector is selective toward organic
compounds
 Its response to a phosphorus atom is
approximately 10 times greater than to a nitrogen
atom and 104 to 106 times larger than to a carbon
atom
 Compared with the FID, the thermionic detector is
approximately 500 times more sensitive to
phosphorus-containing compounds and 50 times
more sensitive to nitrogen-bearing species
 These properties make thermionic detection
particularly useful for sensing and determining the
many phosphorus-containing pesticides.

14. MASS SPECTROMETRY DETECTORS
 The combination of GC with mass spectrometry is
known as GOMS
 The flow rate from capillary columns is generally
low enough that the column output can be fed
directly into the ionization chamber of the mass
spectrometer
 Capillary columns are invariably used in GC/MS
instruments, and such separators are no longer
needed
 Thermal degradation of components can be a
difficulty in GC/MS.

15. APPLICATIONS
01
02
QUALITATIVE ANALYSIS
The peak height or peak area of an
elate from a GC column has been
widely used for quantitative and
semi quantitative analyses
Gas chromatograms are widely used to
establish
the purity of organic compounds
QUANTITATIVE ANALYSIS

16. TEMPERATURE PROGRAMMING
 Temperature programming involves
increasing the temperature of a GC
column as a function of time
 Temperature programming is usually
applied to samples containing a
mixture of components that have
boiling points within a narrow
range
 Temperature programming keeps the
temperature of a GC column at a fixed
value as the separation proceeds

17. REFERENCE
Principles of Instrumental
Analysis
6th Edition
by Douglas A. Skoog , F. James
Holler , Stanley R. Crouch.
Basic Gas
Chromatography 2nd Edition
by Harold M. McNair , James M.
Miller

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