Characterization of Used Cooking Oils
by High Performance Liquid Chromatography
and Corona Charged Aerosol Detection
Marc Plante, Bruce Bailey and Ian N. Acworth
Thermo Fisher Scientific, Chelmsford, MA, USA
Overview
RP-HPLC-Corona ultra R
Purpose: To develop analytical methods to characterize used cooking oils by HPLC.
Methods: High-pressure liquid chromatography (HPLC) methods using the Thermo
Scientific™ Dionex™ Corona™ ultra RS™ Charged Aerosol Detector, ultraviolet
photodiode array detector (DAD), fluorescence detector (FLD), and the Thermo
Scientific™ MSQ Plus™ mass spectrometer (MS) were developed and are detailed.
Results: A variety of cooking oils, five used oils (“gutter oils”) and two fresh oils were
analyzed, and their results are presented. The universal lipids method provided the
fastest and most differentiating results to distinguish different oil qualities, and the
HPLC-FLD-MS method provided information on aldehyde content of the samples.
Introduction
Cooking oils come from a variety of sources, including olive, rapeseed, peanut,
grapeseed, mustard, corn, and many others. Cooking oil must be monitored for quality
and contamination. When cooking oil is heated, it can undergo many chemical changes
including oxidation of unsaturated fatty acids, triglyceride decomposition, and the
formation of potentially cytotoxic oxidation products such as 4-hydroxy-trans-2-nonenal
(HNE) and other aldehydes that are purported to be associated with Parkinsonʼs,
Alzheimerʼs, Huntingtonʼs, atherosclerosis, liver diseases, and stroke. Rancidity during
long term storage can also occur and is associated with the content of polyunsaturated
fatty acid content. Although these issues make used oil unfit for use in the kitchen, and
unhealthy for human consumption, it can still act as a useful resource as a raw material
for biofuels production. As there is a significant price difference between high quality
cooking oils and lower quality biofuel raw materials, the possibility exists for
unscrupulous people to filter and decolorize used cooking oils and sell them as high
quality cooking oils. Such treated used oils are referred to as gutter oils (GO).
To provide some means of distinguishing fresh oil from gutter oil, we developed four
HPLC methods. Three of these methods used the Corona ultra RS charged aerosol
detector to determine different lipid components and ratios that were present in the
samples. A fourth method used sample derivatization, fluorescence and mass
spectrometry to determine aldehyde content.
One method, based on a universal lipids analytical method, separates the majority of
analytes by reversed phase (RP-HPLC) with focus on triacylglycerides (TAG) and their
composition, diacylglycerides, and minor components. A second RP-HPLC method
quantifies the free fatty acids resulting from base hydrolysis of the samples, with
detectable changes in fatty acid composition. A third method, using normal phase
(NP-HPLC), separates the samples by lipid class, including TAGs, free fatty acids, and
DAGs–a faster and simpler result than the first method. The charged aerosol detector
is ideal for these analyses based on its relatively uniform response factor for nonvolatile analytes, and its high sensitivity. The detector operates by nebulizing analytes
after they elute from the column, and placing a charge on the resulting analyte
particles. Peak area is proportional to the amount of analyte (mass) entering the
detector. Typical limits of quantitation are in the single-digit nanograms on column, and
replicate injection precision values are two percent relative standard deviation on peak
area.
Sample Preparation:
HPLC Column:
Column Temp.:
Mobile Phase A:
Mobile Phase B:
Mobile Phase C:
Detector:
Detector Filter:
Nebulizer Temperature:
Sample Temperature:
Flow Rates:
Injection Volume:
Flow Gradients:
1
i
4
M
A
I
C
3
2
2
E
5
Time (min
-5.0
0.0
1.0
2.0
15.0
23.0
30.0
60.0
RP HPLC-Corona ultra R
Sample Preparation: Oil
isopropanol/water (3:2) an
water bath for 1 h with oc
was removed and 25 μL o
HPLC Column:
Column Temp:
Mobile Phase A:
Mobile Phase B:
T
3
M
A
(
Detector:
C
Detector Filter:
3
Nebulizer Temperature: 1
Flow Rate:
E
I
Injection Volumes:
5
Flow Gradients:
Time (min)
0.0
1.0
13.0
22.0
24.0
A fourth method, for aldehyde determination using HPLC with fluorescence (FLD) and
mass spectrometry of derivatized oil samples, is also described with associated results.
Identifications of aldehyde degradant components were made by mass spectrometry.
29.0
NP-HPLC-Corona ultra R
Methods
.
Liquid Chromatography System: Reversed Phase
HPLC System:
UltiMate 3000 DGP-3600RS pump, WPS-3000RS autosampler,
and TCC-3000RS column oven
Liquid Chromatography System: Normal Phase
HPLC System:
UltiMate 3000 LPG-3400SD pump, WPS-3000RS autosampler,
and TCC-3000RS column oven
2 Characterization of Used Cooking Oils by High Performance Liquid Chromatography and Corona Charged Aerosol Detection
Sample Preparation:
HPLC Column:
Mobile Phase A:
Mobile Phase B:
Mobile Phase C:
Detector:
PowerFunction:
Detector Filter:
Nebulizer Temp.:
Sample Temperature:
Flow Rate:
Injection Volumes:
~
G
4
I
M
i
(
C
2
5
1
1
1
1
used cooking oils by HPLC.
methods using the Thermo
Detector, ultraviolet
(FLD), and the Thermo
veloped and are detailed.
oils”) and two fresh oils were
lipids method provided the
rent oil qualities, and the
e content of the samples.
ive, rapeseed, peanut,
must be monitored for quality
dergo many chemical changes
decomposition, and the
as 4-hydroxy-trans-2-nonenal
ociated with Parkinsonʼs,
s, and stroke. Rancidity during
the content of polyunsaturated
nfit for use in the kitchen, and
eful resource as a raw material
erence between high quality
possibility exists for
g oils and sell them as high
o as gutter oils (GO).
utter oil, we developed four
a ultra RS charged aerosol
os that were present in the
orescence and mass
od, separates the majority of
acylglycerides (TAG) and their
second RP-HPLC method
sis of the samples, with
thod, using normal phase
ng TAGs, free fatty acids, and
The charged aerosol detector
response factor for nonperates by nebulizing analytes
n the resulting analyte
alyte (mass) entering the
git nanograms on column, and
ve standard deviation on peak
RP-HPLC-Corona ultra RS Universal Lipids Method
Sample Preparation:
100 µL (or equivalent mass) of sample dissolved
in 900 µL methanol /chloroform (1:1)
HPLC Column:
Thermo Scientific™ Accucore™ C8, 2.6 µm 4.6 × 150 mm HPLC
Column Temp.:
40 °C
Mobile Phase A:
Methanol/water/acetic acid (650:350:4)
Mobile Phase B:
Acetonitrile
Mobile Phase C:
Isopropyl alcohol
Detector:
Corona ultra RS
Detector Filter:
3
Nebulizer Temperature: 20 °C
Sample Temperature:
20 °C
Flow Rates:
Elution Pump: 0.8 mL/min, Inv. Grad. Pump: 1.2 mL/min
Injection Volume:
5 µL
Flow Gradients:
Elution
Inverse
Time (min)
-5.0
0.0
mp, WPS-3000RS autosampler,
%A
%B
100
2.0
30.0
0
23.0
50
100
0
35
%A
0.0
0.0
66.7
33.3
2.7
33.3
33.3
33.3
23.7
66.7
-5.0
1.7
0
15.7
0
30.7
0
100
Time (min)
0
0
55
0
60.0
0
0
50
45
0
0
100
15.0
%C
0
100
1.0
65
60.7
%B
0.0
%C
66.7
0.0
33.3
66.7
40.0
33.3
26.7
33.3
0.0
66.7
33.3
0.0
66.7
33.3
33.3
0.0
RP HPLC-Corona ultra RS Method for Omega Lipids/Free Fatty Acids
Sample Preparation: Oil samples (50 μL aliquot) were dissolved/dispersed in 5 mL
isopropanol/water (3:2) and 1 mL of 5 M KOH. All samples were heated in an 80 °C
water bath for 1 h with occasional stirring. After samples were cooled, a 500 μL aliquot
was removed and 25 μL of formic acid was added to neutralize the sample.
HPLC Column:
Column Temp:
Mobile Phase A:
Mobile Phase B:
Thermo Scientific™ Acclaim™ C30, 3 µm, 3.0 × 250 mm
30 °C
Methanol/MP B/acetic acid (900:100:3.6)
Acetone/acetonitrile/tetrahydrofuran/acetic acid
(675:225:100:4)
Detector:
Corona ultra RS
Detector Filter:
3
Nebulizer Temperature: 10 °C
Flow Rate:
Elution Pump: 1.0 mL/min,
Inv. Grad. Pump: 1.0 mL/min
Injection Volumes:
5 µL
Flow Gradients:
Elution
Inverse
Time (min)
%A
%B
Time (min)
40
60
1.0
0.0
100
13.0
30
70
24.0
5
95
1.0
22.0
with fluorescence (FLD) and
scribed with associated results.
made by mass spectrometry.
mp, WPS-3000RS autosampler,
Flow Gradient:
29.0
5
100
0
95
0
0.0
2.0
14.0
23.0
%A
%B
5
95
5
65
75
100
25.0
100
29.0
5
25.0
5
Mobile Phase A:
Mobile Phase B:
Mobile Phase C:
Detector:
PowerFunction:
Detector Filter:
Nebulizer Temp.:
Sample Temperature:
Flow Rate:
Injection Volumes:
0.0
0.0
2.0
6.0
12.0
13.0
13.5
13.7
15.0
16.0
Flow Rate
(mL/min)
1.0
1.0
1.0
1.0
1.0
1.2
1.2
1.2
1.2
1.2
Aldehydes Analyzed by Rev
Sample preparation: A 500 µ
tetrahydrofuran), was mixed w
tube. The solution was heated
(10,000 g for 3 mins), and the
The Hantzsch reagent was pre
of water was mixed prior to the
a 1 mL volume of formic acid a
solution was brought to a 20 m
HPLC Column:
Mobile Phase A:
Mobile Phase B:
Detector 1:
Wavelengths:
Sensitivity:
Detector 2:
Probe Temperature:
Ionization:
Dwell Times:
Flow Rate:
Injection Volumes:
Flow Gradient:
Accla
Wate
n-pro
UltiM
Excita
2, Da
MSQ
400 °
+mod
1.00
0.5 m
1 µL
Tim
95
35
25
0
0
95
95
NP-HPLC-Corona ultra RS Method for Acylglycerols and Free Fatty Acids
Sample Preparation:
HPLC Column:
Time (min)
~40 µL/mL of oil was dissolved in iso-octane/isopropanol (95:5)
Glass-lined, titanium fritted, non-endcapped CN, 3 µm,
4.0 × 150 mm, at 40 °C
Iso-octane
Methyl-t-butyl ether, 0.4% acetic acid
iso-Octane/n-butyl acetate/methanol/acetic acid
(500:167:333:4)
Corona ultra RS charged aerosol detector
2.0
5
15 °C
15 °C
1.0–1.2 mL/min
1–5 µL
Data Analysis
All HPLC chromatograms were
Dionex™ Chromeleon™ Chrom
Results
RP-HPLC-Corona ultra RS d
Qualitative comparisons were
and the chromatogram overlay
differences between gutter oil
acid peak area), monoglycerid
and there was a change in the
indicated by the relative amou
is calculated using C-2n, wher
double bonds in the alkyl chain
used oils. Levels of analytes th
and GOs are highlighted in red
oleic acid, DAG, and TAG com
chromatogram, and the ECN a
Thermo Scientific Poster Note • PN70536_AOCS_2014_E_05/14S 3
ethod
Flow Gradient:
ass) of sample dissolved
oroform (1:1)
ucore™ C8, 2.6 µm 4.6 × 150 mm HPLC
cid (650:350:4)
in, Inv. Grad. Pump: 1.2 mL/min
Time (min)
-5.0
0.0
Inverse
%A
%B
0.0
%C
66.7
33.3
0.0
66.7
33.3
2.7
33.3
33.3
33.3
23.7
66.7
0.0
1.7
0.0
15.7
66.7
40.0
30.7
26.7
66.7
60.7
33.3
33.3
33.3
0.0
66.7
33.3
33.3
0.0
Lipids/Free Fatty Acids
were dissolved/dispersed in 5 mL
samples were heated in an 80 °C
amples were cooled, a 500 μL aliquot
d to neutralize the sample.
aim™
C30, 3 µm, 3.0 × 250 mm
cid (900:100:3.6)
ahydrofuran/acetic acid
Time (min)
0.0
0.0
2.0
6.0
12.0
13.0
13.5
13.7
15.0
16.0
Flow Rate
(mL/min)
1.0
1.0
1.0
1.0
1.0
1.2
1.2
1.2
1.2
1.2
HPLC Column:
Mobile Phase A:
Mobile Phase B:
Detector 1:
Wavelengths:
Sensitivity:
Detector 2:
Probe Temperature:
Ionization:
Dwell Times:
Flow Rate:
Injection Volumes:
Flow Gradient:
1.0
5
2.0
14.0
23.0
65
75
100
25.0
100
29.0
5
25.0
5
%B
Time (min)
95
25
0
0
95
95
cerols and Free Fatty Acids
solved in iso-octane/isopropanol (95:5)
ed, non-endcapped CN, 3 µm,
% acetic acid
ate/methanol/acetic acid
d aerosol detector
0
0
0
0
0
60
80
0
0
0
%A
%B
98
2
98
98
45.0
65
62.0
5
52.0
95
35
0
0
5
7
40
0
0
80
60
0
Acclaim 120 C18, 3 µm, 3.0 × 150 mm at 50 °C
Water
n-propanol
UltiMate 3000 FLD-3400RS Fluorescence detector
Excitation: 388 nm Emission: 455 nm
2, Data Collection: 5 Hz
MSQ Plus mass spectrometer
400 °C
+mode ESI, Cone potential: +75 V
1.00 s for SIM, 4.00 s for FSM
0.5 mL/min, flow split (1:1) between FLD and MS
1 µL
2.0
Inverse
5
100
100
95
93
60
40
20
20
40
100
FIGURE 1. HPLC-Coro
gutter oils, normalized
The Hantzsch reagent was prepared as follows: 15 mL of denatured alcohol and 1 mL
of water was mixed prior to the addition of 2 g of ammonium fromate. Once dissolved,
a 1 mL volume of formic acid and 50 mg of 1,3-cyclohexanedione was added. The
solution was brought to a 20 mL volume through the addition of denatured alcohol.
0.0
0.0
%C
Sample preparation: A 500 µL aliquot of oil sample solution (10 mg/mL in
tetrahydrofuran), was mixed with 1000 µL of Hantzsch reagent in a 1.5 mL centrifuge
tube. The solution was heated at 75 °C for 1 hour. Samples were centrifuged
(10,000 g for 3 mins), and the supernatant was transferred to an HPLC vial.
-5.0
%A
%B
Aldehydes Analyzed by Reversed-Phase HPLC with FLD and MS Detection
in,
L/min
Time (min)
%A
From a qualitative obser
being a cloudy, rancid ge
triglycerides, and highes
65.0
5
98
2
2
35
95
95
2
Data Analysis
All HPLC chromatograms were obtained and compiled using Thermo Scientific™
Dionex™ Chromeleon™ Chromatography Data System software, 7.1 SR 1.
Results
RP-HPLC-Corona ultra RS detector Universal Lipids Method
Qualitative comparisons were made between gutter oil samples and fresh soybean oil,
and the chromatogram overlays are shown in Figure 1. Relative to the fresh oil, a few
differences between gutter oil and soybean oil were found: fatty acid (measured by oleic
acid peak area), monoglyceride, and DAG amounts increased, while TAGs decreased;
and there was a change in the triglyceride distribution to heavier triglycerides, as
indicated by the relative amounts of equivalent carbon number triglycerides (ECN). ECN
is calculated using C-2n, where C is the number of carbon atoms and n is the number of
double bonds in the alkyl chains. Other unidentified analyte peaks were also noted in the
used oils. Levels of analytes that showed significant differences between soy bean oils
and GOs are highlighted in red in Table 1. For comparison purposes the values for the
oleic acid, DAG, and TAG component areas are relative to total peak area in the
chromatogram, and the ECN amounts are relative to the total TAG peak area.
4 Characterization of Used Cooking Oils by High Performance Liquid Chromatography and Corona Charged Aerosol Detection
TABLE 1. Relative peak
gutter oil samples.
Oil
Soybean-1
Soybean-2
GO1
GO2
GO3
GO4
GO5
Oleic Acid
(Area-%)
0.02
0.03
1.21
0.93
0.02
1.46
2.47
RP HPLC-Corona ultra
Samples were hydrolyze
acid profiles of the differ
chromatogram overlays
the fatty acid profile of th
-55V) revealed saturated
the results found in the U
acids compared to oleic
FIGURE 2. HPLC-Coron
oil (red) and a gutter oil
%B
%C
0
0
5
7
40
0
0
80
60
0
0
0
0
0
0
60
80
0
0
0
From a qualitative observation, the gutter oils GO4 and GO5 were of the least quality,
being a cloudy, rancid gel. This is reflected in the high free oleic acid content, low
triglycerides, and highest ECN 52:ECN 40 ratios.
FIGURE 1. HPLC-Corona detector chromatogram of unused soybean oil and five
gutter oils, normalized to the ECN 46 peak.
NP-HPLC-Corona ultra
Oil samples were prepa
separates by the polar/h
separated from the trigly
acids and less triglyceri
summarized in Table 2.
diglyceride content relat
TABLE 2. Relative pea
normal phase chroma
Oil
Soybean-2
GO2
C with FLD and MS Detection
Aldehydes Analyzed
mple solution (10 mg/mL in
tzsch reagent in a 1.5 mL centrifuge
r. Samples were centrifuged
ransferred to an HPLC vial.
15 mL of denatured alcohol and 1 mL
ammonium fromate. Once dissolved,
yclohexanedione was added. The
the addition of denatured alcohol.
, 3.0 × 150 mm at 50 °C
0RS Fluorescence detector
mission: 455 nm
z
ometer
ntial: +75 V
or FSM
:1) between FLD and MS
%B
2
2
2
35
95
95
2
mpiled using Thermo Scientific™
ystem software, 7.1 SR 1.
TABLE 1. Relative peak area analysis of two unused soybean samples and five
gutter oil samples.
Oil
Soybean-1
Soybean-2
GO1
GO2
GO3
GO4
GO5
Oleic Acid
(Area-%)
0.02
0.03
1.21
0.93
0.02
1.46
2.47
DAG
(Area-%)
3.37
1.10
8.70
14.35
4.50
11.76
11.76
TAG
(Area-%)
96.12
98.77
80.99
82.77
91.82
79.01
79.40
ECN 40
(Area-%)
9.23
7.66
5.62
4.12
11.06
6.38
1.50
ECN 48
(Area-%)
14.29
13.96
24.04
22.81
13.96
23.75
27.90
ECN 52
(Area-%)
2.06
1.39
3.72
4.29
2.33
6.42
6.90
Lipids Method
FIGURE 3. HPLC-FLD-
6,606,897
counts
6,000,000
1.
2.
3.
4.
5.
6.
7.
8.
9.
5,500,000
5,000,000
4,500,000
4,000,000
1
3,500,000
3,000,000
Pea
2,500,000
RP HPLC-Corona ultra RS detector method for Omega Lipids/Free Fatty Acids
2,000,000
Samples were hydrolyzed and analyzed to investigate any differences in the free fatty
acid profiles of the different oil samples. In Figure 2, HPLC-Corona detector
chromatogram overlays of soybean oil (#1) and a gutter oil (GO #5), showing changes in
the fatty acid profile of the two oils as indicated by the arrows. MS analysis (-ve, ESI,
-55V) revealed saturated and unsaturated fatty acids found in soybean oils. Agreeing with
the results found in the Universal method, there were decreases in linoleic and linolenic
acids compared to oleic acid with gutter oil compared to the soybean oil.
1,000,000
FIGURE 2. HPLC-Corona detector chromatogram of fatty acids in unused soybean
oil (red) and a gutter oil (#5) (blue).
tter oil samples and fresh soybean oil,
gure 1. Relative to the fresh oil, a few
ere found: fatty acid (measured by oleic
nts increased, while TAGs decreased;
ution to heavier triglycerides, as
arbon number triglycerides (ECN). ECN
of carbon atoms and n is the number of
ed analyte peaks were also noted in the
ant differences between soy bean oils
mparison purposes the values for the
relative to total peak area in the
e to the total TAG peak area.
Aldehydes in the sampl
Hantzsch synthesis. Ald
used to obtain a molecu
A chromatogram of GO4
Figure 3. Molecular wei
peaks were identified by
shown in this figure are
in unused soybean oil, i
was found in the sample
undergoing analysis.
1,500,000
2
500,000
-200,000
10.0 11.3 12.5 13.8 15.0 16.3
Conclusions
• Four separate HPLC m
unused soybean oil con
• Different “qualities” of g
unused soybean oil and
• The universal lipids met
seen as an increased am
• Of the four methods dev
method provided the mo
• The second method of c
derivatized aldehydes.
• The normal phase meth
samples with DAG and
References
1.
Zarkovic, N. 4-Hydro
Molecular Aspects o
© 2014 Thermo Fisher Scie
property of Thermo Fisher S
encourage use of these pro
of others.
Thermo Scientific Poster Note • PN70536_AOCS_2014_E_05/14S 5
4 and GO5 were of the least quality,
high free oleic acid content, low
am of unused soybean oil and five
NP-HPLC-Corona ultra RS detector method for Acylglycerols and Free Fatty Acids
Oil samples were prepared and analyzed by normal phase chromatography, which
separates by the polar/hydrophilic moieties on the analytes. The free fatty acids were
separated from the triglycerides, and the gutter oils were found to contain more free fatty
acids and less triglycerides than the fresh soybean oil. The results of two oils are
summarized in Table 2. Like the universal lipids method, increases in fatty acid and
diglyceride content relative to the triglycerides was evident in the gutter oil samples.
TABLE 2. Relative peak area analysis for gutter oil #2 and soybean oil #2 by
normal phase chromatography
Oil
Soybean-2
GO2
Free Fatty
Acid
(Area-%)
0.0
0.3
DAG
(Area-%)
TAG
(Area-%)
Other
(Area-%)
0.04
6.8
99.4
91.5
0.56
2.6
Aldehydes Analyzed by Reversed-Phase HPLC and FLD-MS
nused soybean samples and five
ECN 40
(Area-%)
9.23
7.66
5.62
4.12
11.06
6.38
1.50
ECN 48
(Area-%)
14.29
13.96
24.04
22.81
13.96
23.75
27.90
ECN 52
(Area-%)
2.06
1.39
3.72
4.29
2.33
6.42
6.90
Omega Lipids/Free Fatty Acids
gate any differences in the free fatty
2, HPLC-Corona detector
gutter oil (GO #5), showing changes in
the arrows. MS analysis (-ve, ESI,
ids found in soybean oils. Agreeing with
ere decreases in linoleic and linolenic
red to the soybean oil.
m of fatty acids in unused soybean
Aldehydes in the samples were derivatized to their fluorescent acridine forms by the
Hantzsch synthesis. Aldehyde derivatives were measured using HPLC-FLD; MS was
used to obtain a molecular weight and possible identity of each aldehyde derivative.
A chromatogram of GO4, showing a number of aldehyde derivatives is presented in
Figure 3. Molecular weights (m/z) of the acridine derivatives are also given. Aldehyde
peaks were identified by fluorescence and presence of a sodium adduct. All of the peaks
shown in this figure are significantly larger or altogether new, compared to those found
in unused soybean oil, indicating that aldehydes are produced upon heating. No 4-HNE
was found in the samples, possibly due to its reactivity and the age of the samples
undergoing analysis.
FIGURE 3. HPLC-FLD-MS analysis of acridine-derivatized aldehydes found in GO4.
6,606,897
counts
5,500,000
5,000,000
4,500,000
4,000,000
3,500,000
380 nm /455 nm
Peaks
Possible Aldehyde (R-CHO)
1.
m/z 264.23
Glycoaldehyde
2.
m/z 276.05
3.
m/z 281.13
6-hydroxy-2,4-dienal
4.
m/z 322.02
5.
m/z 274.11
6
6.
m/z 288.15
7.
m/z 267.10
8.
m/z 336.93
N/A
9.
6,000,000
1
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
-200,000
5
2
3 4
7
8
9
min
10.0 11.3 12.5 13.8 15.0 16.3 17.5 18.8 20.0 21.3 22.5 23.8 25.0 26.3 27.5 28.8 30.0 31.3 32.5 33.8 35.0 36.3 37.5 38.8 40.0
Conclusions
• Four separate HPLC methods were used to characterize gutter oil compared to
unused soybean oil controls.
• Different “qualities” of gutter oil were also evident, with GO3 consistently closest to
unused soybean oil and GO5 being the worst.
• The universal lipids method still provided some distinguishing characteristic of GO3,
seen as an increased amount of DAG content.
• Of the four methods developed and investigated for this study, the universal lipids
method provided the most consistent determination between used and fresh cooking oils.
• The second method of choice was the aldehyde method, using HPLC-FLD-MS of
derivatized aldehydes.
• The normal phase method would best serve as a fast screening tool for detection of
samples with DAG and free fatty acids present.
References
1.
Zarkovic, N. 4-Hydroxynonenal as a bioactive marker of pathophysiological processes,
Molecular Aspects of Medicine, 2003, 24, 281–291.
© 2014 Thermo Fisher Scientific Inc. All rights reserved. All products and trademarks are the
property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is not intended to
encourage use of these products in any manners that might infringe the intellectual property rights
of others.
PN70536_E 04/14S
6 Characterization of Used Cooking Oils by High Performance Liquid Chromatography and Corona Charged Aerosol Detection
42.0
differences in the free fatty
-Corona detector
(GO #5), showing changes in
ws. MS analysis (-ve, ESI,
d in soybean oils. Agreeing with
eases in linoleic and linolenic
e soybean oil.
y acids in unused soybean
1,000,000
500,000
-200,000
2
3 4
7
8
9
min
10.0 11.3 12.5 13.8 15.0 16.3 17.5 18.8 20.0 21.3 22.5 23.8 25.0 26.3 27.5 28.8 30.0 31.3 32.5 33.8 35.0 36.3 37.5 38.8 40.0
Conclusions
• Four separate HPLC methods were used to characterize gutter oil compared to
unused soybean oil controls.
• Different “qualities” of gutter oil were also evident, with GO3 consistently closest to
unused soybean oil and GO5 being the worst.
• The universal lipids method still provided some distinguishing characteristic of GO3,
seen as an increased amount of DAG content.
• Of the four methods developed and investigated for this study, the universal lipids
method provided the most consistent determination between used and fresh cooking oils.
• The second method of choice was the aldehyde method, using HPLC-FLD-MS of
derivatized aldehydes.
• The normal phase method would best serve as a fast screening tool for detection of
samples with DAG and free fatty acids present.
References
1.
Zarkovic, N. 4-Hydroxynonenal as a bioactive marker of pathophysiological processes,
Molecular Aspects of Medicine, 2003, 24, 281–291.
© 2014 Thermo Fisher Scientific Inc. All rights reserved. All products and trademarks are the
property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is not intended to
encourage use of these products in any manners that might infringe the intellectual property rights
of others.
PN70536_E 04/14S
www.thermoscientific.com
©2014 Thermo Fisher Scientific Inc. All rights reserved. ISO is a trademark of the International Standards Organization.
All other trademarks are the property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is presented as
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