test

2. is by far the most widely used from of
chromatography , particularly by organic
chemists, and it undoubtedly ranks as one of
the most important analytical techniques since
its development in 1952. the separation of
benzene, and cyclohexane is extremely simple
by gas chromatography, but virtually
impossible by conventional distillation.

3. In gas chromatography, the sample is
converted to the vapor state and eluent is a gas.
The stationary phase is generally a nonvolatile
liquid supported on inert solid such as firebrick
or diatomaceous earth. There the mobile phase
that different separations are accomplished.

4. The sample is automatically detected as it
emerges from the column, the sampling side
relative to the reference side signal is fed to
recorder where the chromatography peak are
recorded as a function of the time. By measuring
the retention time and comparing with standard
of the pure substance, it may be possible to
identify peak the area under the peak is
proportional to the concentration and so the
amount of substance can be quantitatively
determined.

5. http://teenet.chiangmai.ac.th/eng/research_details.php?i
d=32

6. Kung khao (Litopenaeus Vannamei) have fatty
acid about 0.43-0.49%, such as ω-6 fatty acids (20:4
n6) ω-3 fatty acids that’s eicosapentaenoic acid
(EPA) and docosahexaenoic acid ( DHA )

7. Khung khao are cleaned and dehulled then chop
to mince
Lipid were extracted by the chloroform-methanol
( 2:1,v/v )
Crude lipid 100 mg were saponified by using
1 ml of 0.5 NaOH in Methanol
and heated for 15 min at 80C.

8. The saponifiable matter was then eterified
by using 2ml of BF3 ( 12% in methanol )
for 5 min at 80C
Fatty acid methyl ester was dilute in hexane by
using 1 ml of hexane for 1 min at 80C
then cooling and add 3ml of saturated NaCl
,stirring and pipette the hexane out
Add and remove hexane against for three more
time. Storage the product in vial at -15C.

9.  Columm : 15% DEGS on Chromosorp 80/120w
 Columm Temp : 150C
 Detector : FID
 Carrier gas : N2
 Detector temperature : 150C
 Standard Fatty acid : Supelco No.47045 : C17
and C18
Fatty acid methyl ester were identified by
comparing the retention time against the
standard.

10. Fig 1. Chromatographic profile of n-Heptadecanoic acid
( C17 ) and Tri-stearin ( C18 ).

11. Fig 2. Total ion Chromatograms of profile of Peneus
merguiiensis lipid sample .

12. Weight of
shrimp ( g )
Total fatty acid
extracted ( g )
% of C18 in total
fatty acid extracted
% of fatty acid C18
in shrimp ( w/w )
20.13 0.36 29.26 0.52

13. Gas Chromatography technique is
importance and rapid and accuracy
method for food science when need
to detected on isolate compound in
food. More ever this technique due
amount of sample are in limit.