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High Sensitivity and Rugged Pesticide
Residue Analysis in Food Samples by
GC/MS Triple Quadrupole
EPRW June 2010Dr. Finbarr O’Regan
Pesticide Control Service,
Department of Agriculture, Fisheries and Food,
Backweston Campus,
Young’s Cross,
Celbridge,
Co. Kildare
• Extraction Methods
• Compound optimisation
• Retention Time Locking
• Limits of Detection
• Linearity
Overview
Agilent 7000A Triple Quadrupole GC/MS
Fruit and veg. Extraction
• Mini-Luke extraction
• Acetone , DCM, Petroleum Ether
• Sodium Sulphate
• GPC Clean-up (also run without GPC)
• Samples made up and run in Ethyl Acetate• Based on standard multi-residue method published as "Analytical
methods for pesticide residues in foodstuffs" 6th Ed. Ministry of Health
Welfare and Sport - The Netherlands
Fat matrix Extraction
• Acetone , Acetonitrile
• Celite clean-up
• GPC Clean-up
• Samples made up and run in Ethyl Acetate
• Based on standard multi-residue method published as "Manual of Pesticide
Analysis - Vol 1" DFG - Deutsche Forschungsgemeinschaft
Milk and Egg extraction
• QuEChERS extraction
• Acetonitrile
• Sodium Acetate/Acetic Acid Buffer,
Magnesium Sulphate and Sodium
Chloride
• Samples made up and run in Ethyl Acetate
• Based on standard multi-residue method published as J. AOAC Int. 88 615-
629 - Steven J. Lehotay, Katerina Mastrovska & Alam R. Lightfield
Optimisation
• 200 compounds in two runs
• Retention Time Locking– Locked to pp-dde
• Limits of Detection– 10ppb for 178 compounds
– 20 - 50ppb for remaining 22 compounds
• Linearity– R2 = 0.999
– (captan and captafol – can be problematic)
GC-QqQ Method Overview
Internal Standard TPP
Quantitation Method
Calibration
Qualifier
Malathion LCL (10ppb)
Malathion Positive
Chlorpyriphos LCL (10ppb)
Chlorpyrifos Positive
EUPT FV11 Cauliflower Matrix
z-scores
MiniLuke
No GPC EU Median
Mini LukeGC-MSD
No GPCGC-QqQ
azinphos-methyl 0.316 0.409 0.355 -0.44 0.61
Boscalid 0.347 0.495 0.414 -0.65 0.78
buprofezin 0.477 0.681 0.638 -1.01 0.27
cadusofos 0.598 0.639 0.611 -0.09 0.18
carbofuran 0.231 0.218 0.283 -0.73 -0.92
EUPT FV11 Cauliflower Matrix
z-scores
MiniLuke
No GPC EU Median
Mini LukeGC-MSD
No GPCGC-QqQ
deltamethrin 0.144 0.162 0.157 -0.33 0.13
diazinon 1.120 1.550 1.250 -0.42 0.96
isofenphos-methyl 0.411 0.570 0.540 -0.96 0.22
l-cyhalothrin 0.213 0.252 0.266 -0.80 -0.21
metaxyl 0.519 0.460 0.450 0.61 0.09
EUPT FV11 Cauliflower Matrix
z-scores
MiniLuke
No GPC EU Median
Mini LukeGC-MSD
No GPCGC-QqQ
methamidophos 0.416 0.387 0.405 0.11 -0.18
methidathion 0.446 0.528 0.472 -0.22 0.47
monocrotophos 0.516 0.420 0.438 0.71 -0.16
sum parathion-methyl 0.358 0.226 0.320 0.48 -1.18
phosalone 0.285 0.412 0.368 -0.90 0.48
EUPT FV11 Cauliflower Matrix
z-scores
MiniLuke No GPC
EU Median
MiniLuke No GPC
procymidone 0.676 0.811 0.780 -0.53 0.16
triazophos 0.450 0.631 0.538 -0.65 0.69
Thank you for your attention …
… questions?