FattyAcids (Free)
GC
Rtx®-200
FattyAcids (Free)
GC
Stabilwax®-DA
FOODS, FLAVORS, & FRAGRANCES
2
Phone: 800-356-1688 or 814-353-1300
Fats & Oils
GC_FF00653
Stabilwax
®
-DA 30m, 0.32mm ID, 0.25µm (cat.# 11024)
Sample:
1.0µL FFAMix
Solvent:
water
Conc.:
5mg/mL inmethanol
Inj.:
splitless/250°C
Splitless hold time:
0.25min.
Carrier gas:
hydrogen (constant flowmode)
Flow rate:
6.0mL/min.
Split flow:
75mL/min.
Det.:
FID/250°C
Inlet liner:
laminar cup splitter
Oven temp.:
40°C to 250°C@
10°C/min. (hold 15min.)
Peak List:
1. butyric acid
C4:0
2. caproic acid
C6:0
3. caprylic acid
C8:0
4. capric acid
C10:0
5. lauric acid
C12:0
6. myristic acid
C14:0
7. palmitic acid
C16:0
8. stearic acid
C18:0
9. oleic acid
C18:1
10. linoleic acid
C18:2
11. linolenic acid
C18:3
12. arachidic acid C20:0
13. behenic acid
C22:0
1
2
3
4
5
6
7 8
9
min.
1
2
3
4
GC_CH00282
30m, 0.25mm ID, 0.25µmRtx
®
-200 (cat.# 15023)
Sample:
0.8µL split injection of a free
fatty acid standard.
Conc.:
approximately 10 to 20ng/µL.
Oven temp.:
90°C
Inj. & det. temp.:
250°C
Carrier gas:
hydrogen
Linear velocity:
40cm/sec.
(flow rate: 1.4cc/min.)
FID sensitivity:
4 x 10
-11
AFS
Split vent:
40cc/min.
Peak List:
1. acetic acid
2. propionic acid
3. isobutyric acid
4.
n
-butyric acid
5. isovaleric acid
6.
n
-valeric acid
7. isocaproic acid
8. caproic acid
9. heptanoic acid
AnalyzingFats&Oils
In foods, fats serve several functions—providing
flavor, texture, and serving as a source of essential
fattyacids and fat-solublevitamins.Lipids are sub-
stances in foods that are soluble inanon-polar sol-
vent, such as hexane, benzene, or chloroform/
methanol. They include compounds such as glyc-
erides, free fatty acids, phospholipids, glycolipids,
terpenes, sterols, andwaxes. Lipids can be divided
into three general groups: 1) simple lipids, which
include fats andwaxes; 2) compound lipids,which
include phospholipids and glycolipids; and 3)
derived lipids, which include fatty acids, alcohols,
and sterols. Over 90% of the lipids found in food
arepresent as triglycerides–esters of fatty acids and
glycerol.
FreeFattyAcids
Free fattyacidmolecules consistof carbonchainsof
varying lengths with an acidic group (-COOH) at
one end of the molecule. Fatty acids with chain
lengths of 2–20 carbon atoms account for up to
10% of the lipid content in food. In general, these
fatty acids are straight chainmolecules, either fully
hydrogenated or with some degree of unsaturation
(i.e., double bonds). Because free fatty acids are
adsorptive and the longer chain acids lack volatility,
analysis of these compounds can be difficult. The
acidscanbeconverted tomethyl estersandanalyzed
by GC, but the additional sample preparation
required to do this increases time and cost. The
analysisof free fattyacidswithoutderivatizationcan
beaccomplishedusinga
Stabilwax®-DA
column, a
bondedCarbowax
®
column specifically deactivated
for acidic compounds. Tominimize loss from dis-
crimination in the injectionport, direct injection is
recommended, although splitless injections can be
used.Foradditional examplesof organicacidanaly-
sis, seepages 14-15.
for
more
info
Request ApplicationsNoteGCAnalysis of Free Fatty Acids on
Stabilwax
®
-DAColumns (cat.# 59155B).
Also see page 15!
