Gas Chromatography

1. Chromatography
(Gas Chromatography)
Presented By:-
Ruta Satoskar
&
Suman Muthu

2. THE CHROMATOGRAPHIC PPRROOCCEESSSS -- PPAARRTTIITTIIOONNIINNGG
(gas or liquid)
MMOOBBIILLEE PPHHAASSEE
SSTTAATTIIOONNAARRYY PPHHAASSEE
Sample
out
Sample
in
(solid or heavy liquid coated onto a solid or support system)

3. OOrriiggiinnaall CChhrroommaattooggrraapphhyy EExxppeerriimmeenntt
Later
An EtOH extract
of leaf pigments
is applied to the
top of the column.
EtOH is used to
flush the pigments
down the column.

4. Common Types of Chromatography
Tswett’s technique is based on Liquid Chromatography. There
are now several common chromatographic methods. These
include:
1. Paper Chromatography
2. Thin Layer Chromatography (TLC)
3. Liquid Chromatography (LC)
4. High Pressure Liquid Chromatography (HPLC)
5. Ion Chromatography
6. Gas Chromatography (GC)

5. How Does Chromatography
Work?

6. EEqquuaattiioonn ffoorr PPaarrttiittiioonn RRaattiioo
A A
A
A
A
A
A
A
A
A
A
A
K = distribution
coefficient or
partition ratio
K =
CS
CM
Where CS is the molar
concentration of the
solute in the stationary
phase and CM is the
molar concentration in
the mobile phase.
Cross Section of Equilibrium in a column.
“A” are adsorbed to the stationary phase.
“A” are traveling in the mobile phase.

8. GGaass CChhrroommaattooggrraapphhyy
• TThhee ffaatthheerr ooff mmooddeerrnn
ggaass cchhrroommaattooggrraapphhyy iiss
NNoobbeell PPrriizzee wwiinnnneerr JJoohhnn
PPoorrtteerr MMaarrttiinn,, wwhhoo aallssoo
ddeevveellooppeedd tthhee ffiirrsstt
lliiqquuiidd--ggaass
cchhrroommaattooggrraapphh.. ((11995500))

9. BB..DD ooff GG..CC..

10. Criteria for CCoommppoouunnddss ttoo bbee AAnnaallyyzzeedd bbyy GG..CC
1.VOLATILITY.
2.THERMOSTABILITY.

11. CChhrroommaattooggrraapphhiicc SSeeppaarraattiioonn
--DDeeaallss wwiitthh bbootthh tthhee ssttaattiioonnaarryy pphhaassee aanndd
tthhee mmoobbiillee pphhaassee..
• MMoobbiillee –– iinneerrtt ggaass uusseedd aass ccaarrrriieerr..
• SSttaattiioonnaarryy –– lliiqquuiidd ccooaatteedd oonn aa ssoolliidd oorr
aa ssoolliidd wwiitthhiinn aa ccoolluummnn..

12. CChhrroommaattooggrraapphhiicc SSeeppaarraattiioonn
• CChhrroommaattooggrraapphhiicc SSeeppaarraattiioonn
– IInn tthhee mmoobbiillee pphhaassee,, ccoommppoonneennttss ooff tthhee ssaammppllee
aarree uunniiqquueellyy ddrraawwnn ttoo tthhee ssttaattiioonnaarryy pphhaassee aanndd
tthhuuss,, eenntteerr tthhiiss pphhaassee aatt ddiiffffeerreenntt ttiimmeess..
– TThhee ppaarrttss ooff tthhee ssaammppllee aarree sseeppaarraatteedd wwiitthhiinn tthhee
ccoolluummnn..
–CCoommppoouunnddss uusseedd aatt tthhee ssttaattiioonnaarryy pphhaassee rreeaacchh
tthhee ddeetteeccttoorr aatt uunniiqquuee ttiimmeess aanndd pprroodduuccee aa
sseerriieess ooff ppeeaakkss aalloonngg aa ttiimmee sseeqquueennccee..

13. Se Chromatographic Seppaarraattiioonn AA((ccoonnttiinnuueedd))
– TThhee ppeeaakkss ccaann tthheenn bbee rreeaadd aanndd aannaallyyzzeedd bbyy
aa ffoorreennssiicc sscciieennttiisstt ttoo ddeetteerrmmiinnee tthhee eexxaacctt
ccoommppoonneennttss ooff tthhee mmiixxttuurree..
–RReetteennttiioonn ttiimmee iiss ddeetteerrmmiinneedd bbyy eeaacchh
ccoommppoonneenntt rreeaacchhiinngg tthhee ddeetteeccttoorr aatt aa
cchhaarraacctteerriissttiicc ttiimmee..

14. CChhrroommaattooggrraapphhiicc AAnnaallyyssiiss
– TThhee nnuummbbeerr ooff ccoommppoonneennttss iinn aa ssaammppllee iiss
ddeetteerrmmiinneedd bbyy tthhee nnuummbbeerr ooff ppeeaakkss..
– TThhee aammoouunntt ooff aa ggiivveenn ccoommppoonneenntt iinn aa ssaammppllee iiss
ddeetteerrmmiinneedd bbyy tthhee aarreeaa uunnddeerr tthhee ppeeaakkss..
– TThhee iiddeennttiittyy ooff ccoommppoonneennttss ccaann bbee ddeetteerrmmiinneedd
bbyy tthhee ggiivveenn rreetteennttiioonn ttiimmeess..

15. GRAPHICAL ANALYSIS

16. CARRIER GAS
» Hydrogen
• Better thermal conductivity
• Disadvantage: it reacts with unsaturated compounds
& inflammable
» Helium
• Excellent thermal conductivity
• It is expensive
» Nitrogen
• Reduced sensitivity
• It is inexpensive

17. RReeqquuiirreemmeennttss ooff aa ccaarrrriieerr ggaass
Inertness
Suitable for the detector
High purity
Easily available
Cheap
Should not cause the risk of fire
Should give best column performance

18. AADDVVAANNTTAAGGEESS OOFF GG..CC
1. Very high resolution power, complex mixtures can be
resolved into its components by this method.
2. Very high sensitivity with TCD, detect down to 100
ppm
3. It is a micro method, small sample size is required
4. Fast analysis is possible, gas as moving phase-rapid
equilibrium
5. Relatively good precision & accuracy
6. Qualitative & quantitative analysis is possible

19. Disadvantages of G.C.
1. The samples analysed are limited to those that
are volatile or can be made volatile.
2. The samples must be thermally stable to
prevent degradation when heated.
3. Cannot be used to prepare samples for further
analysis once separated.
4. Problems can be encountered when injecting
the sample

20. Applications of G.C
• G.C is capable of separating, detecting & partially
characterizing the organic compounds , particularly
when present in small quantities.
1, Qualitative analysis
Rt & RV are used for the identification & separation
2, Checking the purity of a compound
Compare the chromatogram of the std. & that of the
sample

21. Applications of G.C
3, Quantitative analysis
It is necessary to measure the peak area or peak
height of each component
4, Used for analysis of drugs & their metabolites.

22. The Next Generation in Gas
Chromatography