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QuEChERS Sample Prep and its Cleanup Effectiveness and
Efficiency – A Look at Sorbents
QuEChERS1. Extraction of Pesticides With Acetonitrile, MgSO4 and Salt
Cleanup of Fatty Acids with Primary Secondary Amine
Cleanup of Pigments with GCB
Cleanup of Sterols and Non-polar interferentswith C18 Silica
2. Dispersive Solid Phase Extraction (dSPE) Cleanup of Interferents
O
OH
O
OHH3C
H3C
Palmitic Acid
Stearic Acid
Chlorophyll a
Campesterol
Pigmented Sample Issues
• Liner Fouling• Column Retention Time
Shortens• Peak Tailing
Carrot Pea Pineapple Raspberry
Liner with 50 Injections of Spinach Extract after dSPEcleanup with GCB
Spiked spinach QuEChERS extracts (at 625 ng/mL)w/o GCB clean‐up (5 μL PTV injections)
Not OK after100 injections
Slide from Steven Lehotay, USDA-ARS
0.0 20.0 40.0 60.0 80.0 100.0 120.0
Chlorothalonil
Chlorpyrifos-methyl
DCBP
Chlorpyrifos
Folpet
Coumaphos
Recovery (%)
N
N
ClCl
Cl
Cl
N
O
O
S
C
Cl
Cl Cl
Current Solution – GCB
A New Engineered Carbon Material
CarbonX GCB Before AfterAfter
Effect of Glass Microscope Slide Weight on Particle Diameter
Intact particlesafter grinding
Crushed Particles
Pore Diameter (A)
Pore
Vol
(cm3 /g
)
Repeatable and Reproducible Pore Structure
80 A avg pore
0
0.2
0.4
0.6
0.8
1
1.2
0 100 200 300 400
Carb
onX
GCB
SPE1
Time (
min)
Time to elute 4 mL of CH2Cl2 from 3 mL SPE Cartridge under gravity flow. N= 10. GCB cartridge is commercially packed & sourced.
More Reproducible Flow Characteristics
100 um
Color results from 3 cleanup styles GCBGCB w/ Tol
CarbonX Plus
Spinach Extract
Recoveries from 3 cleanup styles
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
Dic
hlor
vos
Phen
ylPh
enol
Lind
ane
Dia
zino
n
Chl
orot
halo
nil
Chl
orpy
rifos
-met
hyl
Dic
hlor
oben
zoph
enon
e
Chl
orpy
rifos
Hep
tach
lorE
poxi
de
Folp
et
Gam
maC
hlor
dane
Alph
aChl
orda
ne
Die
ldrin
DD
E
Ethi
on
Endo
sulfa
nSul
fate
Perm
ethr
ine
Cou
map
hos
Rec
over
y (%
)
CarbonX PlusGCBGCB Toluene
Cleanup Style Affects SIM Baseline
CarbonX Plus
GCB
GCB w/Tol
Cleanup Efficiency – X and Y axis
88
90
92
94
96
98
100
102
0 5 10 15 20 25 30 35 40 45 50
Injection Number
Ave
rage
Rec
over
y of
Pes
ticid
es (N
orm
aliz
ed to
Initi
al R
ecov
erie
s)
GCBCarbonX Plus
Powdered Botanicals - Extreme Fatty Acid Cleanup
Saw Palmetto Uncleaned
Saw Palmetto 450 mg PSA added to AOAC Pigmented dSPE Tube
Powdered Botanicals - Extreme Fatty Acid Cleanup
Ginkgo Biloba Uncleaned
Ginkgo Biloba 250 mg PSA added to AOAC Pigmented dSPE Tube
Good Recoveries After Cleanup
0.0
20.0
40.0
60.0
80.0
100.0
120.0Dichlorvos
Phen
ylph
enol
Atrazine
Lind
ane
Diazino
n
Chlorothalon
il
Chlorpyrifo
s‐methyl
DCB
P
Chlorpyrifo
s
Hep
techlor Ep
oxide
Folpet
γ chlordane
α chlordane
Dieldrin
DDE
Ethion
Endo
sulfa
n Sulfa
te
Perm
ethrin
Coum
apho
s
Recovery (%
)
Ginkgo Biloba
Saw Palmetto
Miniaturize and Automate - ITSP
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
Dic
hlor
vos
Phen
ylph
enol
Atr
azin
e*
Lind
ane
Dia
zino
n
Chl
orot
halo
nil
Chl
orpy
rifos
-met
hyl
DC
BP
Chl
orpy
rifos
Hep
tech
lor E
poxi
de
Folp
et
γ ch
lord
ane
α ch
lord
ane
Die
ldrin
DD
E
Ethi
on
Endo
sulfa
n Su
lfate
Perm
ethr
in
Cou
map
hos
Rec
over
y (%
)
1. Condition with 100 µL 1% Acetic Acid ACN
2. Inject 100 µL of Sample Extract
3. Elute with 100 µL 1% Acetic Acid ACN
Conclusions• Superior QuEChERS Recoveries with
Engineered Carbon for GC/MS• Similar Color Removal• Greater than 75% recovery for planar pesiticides• Toluene Unnecessary• Decreased Liner and Column Fouling• Sometimes Extreme Issues Can Necessitate
Extreme Cleanup Solutions• Miniaturization Can Assist when Sample Volume
is an Issue or Automation is Desired
Confidential
Dr. Jon ThompsonUnited Science
Dr. Chunze LaiR&D
Dr. Li ChenR&D
Dr. Conor SmithR&D
Prof. Dwight StollGustavus
Doug FryerProduct Manager