Multi-class pesticides analysis
in challenging vegetable
matrices using fast 5 msec
MRM with 15 msec polarity
switching
ASMS 2012
WP27-575
Yuka Fujito1, Yusuke Inohana2, Kiyomi Arakawa2,
Ichiro Hirano2
1
Shimadzu Analytical & Measuring Center, Inc.,
Kyoto, Japan ;
2
Shimadzu Corporation, Kyoto, Japan
Multi-class pesticides analysis in challenging vegetable matrices
using fast 5 msec MRM with 15 msec polarity switching
Introduction
Many regulatory authorities have established multi-class
residual pesticides methods for the analysis of vegetables,
fruits and other food stuffs. There is, however no global
agreement on the provision of a target list of pesticides and
this presents a risk with products moving between different
regulatory requirements. In order to eliminate this risk, food
safety laboratories need to ideally screen as many
compounds as possible in a single run which may reach
maximum residual limits (MRL); typically 10 ppb in food
matrices.
In this study, we report the application of ultra-fast 5 msec
MRM with 15 msec polarity switching for the analysis of
138 pesticides in vegetable matrices (72 and 66
compounds measured by LC-QqQ and GC-QqQ in the
European Union Reference Laboratory (EURL) method) .
Materials and Methods
Sample Preparation (QuEChERS EU method)
Food sample
Analytical Conditions
Vegetables
Origin
Paprika (Sweet pepper) New Zealand
Leek (Garlic chives)
Japan
HPLC : Nexera UHPLC system
Column
: Shim-pack XR-ODSII (75 mm x 2 mmI.D., 2.2 um)
Mobile phase
: A ; 2 mM ammonium formate containing 0.1%
formic acid – water
B ; Methanol
Gradient program
: 5% B (0-2.5 min.)→55% B (2.51-6 min.)→80%
B (6.01-12 min.) →100% (12-15 min.)→5%
(15.01-20 min.)
Flow rate
: 0.2 mL / min.
Column temperature : 40°C
Step 1 : Sample Extraction
1. Homoginize vegetables with food processor and homoginizer
2. Weigh 10 g homoginized sample
1
Add 10 mL acetonitrile
Add Salt-mixture
*1
・4 g
・1 g
・0.5 g
・1 g
LC/MS/MS analysis
3
MS : LCMS-8040 Triple quadrupole mass spectrometer
MgSO4
NaCl
Na2H citrate・1.5H2O
Na3 citrate・2H2O
4
Extract 1
3. Shake vigorously by hand 1 min.
4. Centrifuge for 5 min. at 4000 rpm (Extract 1)
*1 : Citrate Extraction Tube
(SIGMA ALDRICH)
5. Transfer 6 mL Extract 1 into Dispersive SPE tube*2
containing
・900 mg
・150 mg
・45 mg
: ESI (Positive / Negative)
: +4.5 kV / -3.5 kV
: 276 MRM transitions (2 MRMs / compound)
Dwell time 5 msec. / Pause time 1 msec.
Features of LCMS-8040
5 times higher sensitivity compared to LCMS-8030
An ultra fast scan speed of 15000 u / sec.
An ultra fast polarity switching of 15 msec.
An ultra fast MRM transition speed of 555 ch./ sec.
Step 2 : Sample Clean up
6. Shake vigorously by hand 2 min.
Ionization
Ion spray voltage
MRM
6
MgSO4
PSA
ENVI-Carb
LCMS-8040
Ultra Fast Mass Spectrometer
7. Centrifuge for 5 min. at 3000 rpm (Extract 2)
8. Transfer 1 mL Extract 2 into a vial
Add 200 uL acetonitrile
9. Vortex sample to mix it
10. Filtrate sample with disposable filter
Extract 2
7
8
Yellow Red Leek
Paprika Paprika
*2 : PSA/ENVI-Carb SPE Clean Up Tube 2 (SIGMA ALDRICH)
Fig. 1 LCMS-8040 Triple Quadrupole Mass Spectrometer
2
Multi-class pesticides analysis in challenging vegetable matrices
using fast 5 msec MRM with 15 msec polarity switching
Results
MRM of pesticide standards
Table 1 LOQs of 138 pesticides in the EURL method by LCMS-8040
Technique
(on the EURL method)
by LC-QqQ
by GC-QqQ
LOQs < 10 ppb
LOQs > 10 ppb
Not Ionization
72 (100%)
47 (71%)
0 (0%)
6 (9%)
0 (0%)
13 (20%)
・71 % of pesticides measured by GC-QqQ in the EURL method could achieved excellent LOQs (0.08-10 ppb) .
Compounds for LC-QqQ
Compounds for GC-QqQ
Carbofuran
Azoxystrobin
Ethion
Area(x100,000,000)
Area(x10,000,000)
Area(x10,000,000)
9.0
Methidathion
Area(x10,000,000)
1.00
7.5
7.5
8.0
0.75
7.0
6.0
5.0
5.0
0.50
5.0
4.0
3.0
2.5
2.0
1.0
1-1000 ppb
r2=0.9992
0
500
Conc.
0
1.75
10 ppb
S/N 38
(1ppb)
1.50
1.25
1.00
500
2.0
2.00
S/N 82
(1ppb)
Conc.
5 ppb
S/N 73
(1ppb)
1.75
0.5
0.25
0.00
0.0
6.0
7.0
5.0
6.0
Conc.
S/N 73
(1ppb)
1.75
1.50
1.25
1.00
0.75
0.75
1 ppb
500
(x100,000)
1.00
1.0
0
(x100,000)
1.25
0.75
0.50
500
1.50
1.5
1-1000ppb
r2=0.9996
0.0
0
Conc.
(x100,000)
(x100,000)
2.00
1-1000ppb
r2=0.9999
0.00
0.0
0.0
2.5
0.25
1-1000 ppb
r2=0.9999
0.50
0.50
0.25
0.25
0.00
0.00
9.0
10.0
6.0
7.0
Fig. 2 Calibration curves and MRM chromatograms of typical pesticides
3
Multi-class pesticides analysis in challenging vegetable matrices
using fast 5 msec MRM with 15 msec polarity switching
Recovery of pesticides in vegetable matrices
Recovery (%)
Clothianidin
▲ (622 %)
240
220
▲ (11439 %)
Fludioxonil
■ Red paprika
◆ Yellow paprika
(out of range)
▲ Leek
200
180
Imidacloprid
Trichlorfon
Azoxytrobin
Kresoxim
160
-methyl
140
120
100
80
60
40
Dichlorvos
Triacloprid
Flutriafol
20
0
Fig. 3 Recovery of pesticides in the vegetable matrices (5 ppb spiked)
Approximately 90% of pesticides represented good recoveries in the range of 70-120% in all studied matrices.
Some pesticides indicating up to 120% of recovery were also detected in the matrix blank (Fig. 4）.
20000
80000
17500
70000
15000
60000
12500
50000
10000
40000
150000
7500
30000
100000
5000
20000
25000
2500
10000
0
0
0
150000
5 ppb standards spiked
Matrix blank
125000
100000
75000
50000
6.0
6.5
4.0
4.5
Imidacloprid
5ppb standards spiked
Matrix blank
MRL (Japan)
250000
200000
50000
3.5
7.0
Azoxystrobin
300000
Azoxystrobin
8.19 ppb
3.77 ppb
5 ppm
0
3.5
4.0
4.5
6.5
Clothianidin
Imidacloprid
8.99 ppb
3.19 ppb
3 ppm
Clothianidin
21.39 ppb
25.78 ppb
15 ppm
7.0
7.5
Fludioxonil
Fludioxonil
556.58 ppb
550.92 ppb
10 ppm
Fig. 4 MRM Chromatograms and quantitative results of 4 pesticides
Conclusion
MRL of pesticide in vegetable matrices pre-treatment by
QuEChERS method could be measured successfully using
fast 5 msec MRM with 15 msec polarity switching.
Majority of pesticides being suggested to GC-QqQ
technology on the EURL method was successfully covered
by LC-QqQ.
4
First Edition: May, 2012
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