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Easy Identification of
Fraudulent Product
Excellent chromatographic separation of choles-
terol, squalene, diglycerides, and triglycerides was
obtained (Figure 1). Once separated, these frac-
tions can be used to confirm the addition of egg fat
by comparing the glyceride profiles of the egg pasta
extract with those from the egg sample. Egg pasta
products adulterated with non-egg sources of cho-
lesterol will not show comparable patterns. Note,
while cholestane often is used as an internal stan-
dard in cholesterol testing, the use of squalene
instead in this method is advantageous as it allows
both cholesterol and the glyceride profiles to be
analyzed. Squalene is highly stable and similar to
cholesterol, but the compounds are well-resolved
on the Rtx®-65TG column. Cholestane is not suf-
ficiently separated from cholesterol on this polar
phase, however, for methods that recommend
cholestane, separations can be accomplished on
the less polar Rxi®-5ms column (Figure 2). In fact,
for methods with a goal of high throughput cho-
lesterol determination, rather than source authen-
tication, using the Rxi®-5ms column under isocratic
conditions can cut analysis time by nearly 50%.
In summary, estimating cholesterol in food prod-
ucts is often part of the authentication testing of
label claims regarding egg content. However, the
presence of cholesterol in a product may be due to
a non-egg source, and the natural variability of
cholesterol levels in eggs further complicates quan-
titative conclusions. The method shown here sim-
plfies fraud detection by incorporating glyceride
testing. Easy comparision of the chromatographic
profiles of egg and egg product (pasta) samples
can be made using an Rtx®-65TG column, which
is specifically tested to assure excellent separations
and a reliable performance for glycerides.
Figure 2
5-minute run times benefit cholesterol methods
requiring high sample throughput instead of source confirmation.
Product Listing
Fraudulent label claims of egg content in egg
pasta can be detectedmore accurately by eval-
uating glycerides and cholesterol, compared
to analyzing cholesterol alone. This simple
method determines both in a single run.
GC_FF00881
GC_FF00882
Column:
Rxi
®
-5ms, 15m, 0.25mm ID, 0.25µm (cat.# 13420)
Sample:
1,000µg/mL cholesterol in DMF, 1,000µg/mL 5-
α
-cholestane in hexane;
25ng cholesterol, 150ng 5-
α
-cholestane on column
Inj.:
1.0µL, split (20:1), single gooseneck inlet liner w/wool (cat.# 22405)
Inj. temp.:
250°C
Carrier gas:
helium, constant pressure (9.7psi @ 200°C)
Linear velocity: 24cm/sec.
Oven temp.:
see above
Det.:
FID @ 340°C
1. 5-
α
-cholestane (IS)
2. cholesterol
A. Isothermal conditions maximize
sample throughput
Oven temp.:
300°C (hold 10 min.)
B. Temperature program conditions
Oven temp.:
200°C (hold 1 min.) to 330°C @
20°C/min. (hold 7.5 min.)
Rtx®-65TG Columns (fused silica)
(Crossbond
®
65% diphenyl/35% dimethyl polysiloxane)
ID df (µm)
temp. limits
length cat. #
price
0.25mm 0.10
40 to 370°C
30-Meter 17008
Rxi®-5ms Columns (fused silica)
(Crossbond
®
5% diphenyl/95% dimethyl polysiloxane)
ID df (µm)
temp. limits
length cat. #
price
0.25mm 0.25 -60 to 330/350°C 15-Meter 13420
QuEChERS
For more information on
Restek’s line of QuEChERS
products visit us at:
www.restek.com/quechers