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Results and Discussion
Prim ary and secondary amine exchange material (PSA) is the base sorbent used for dSPE cleanup of Qu EChERS fruit and vegetable extr acts
because it removes many organic acids and sugars that might act as instrumental interferences.
A pesticide-spiked strawberry extract (200ng/mL) subjected to dSPE with PSA was used to generate on e-point calibration curves. Spiked
strawberry extr acts subjected to additional dSPE sorbents were analyzed and the results versus PSA dSPE are shown as percent recoveries in
Table III. CIS is suggested for use when samples might conta in fats; not an issue for a strawberry extract, but it was important to verify that
gross losses of more hydrophobic pesticides (e.g. Endrin and DDT) would not occur. GCB is used to remove pigments, and when treated, the
pink/red strawberry extract became clear. However, GCB can also have a negative effect on certain pesticides, especially those that can assume
a planar shape like chlorothalon il and thiab enda zole.
Restek dSPE products in a variety of standard sizes and formats make Qu EChERS even simpler. The centrifuge tube format, available in 2mL
and 15mL sizes, contains magn esium sulfate (to partition water from organ ic solvent) and a choice of SPE sorbents, including PSA (to remove
sugars and fatty acids), CIS (to remove nonpolar interferences such as fats), and GCB (to remove pigments and sterols). Custom products
also are available by requ est. If you are frustrated by the time and cost involved with your current approach to pesticide sample cleanup, we
suggest you tr y this simple and economic al new method.
References
1. MichelangeloAnastassiades, Steven J.Lehotay, Darinka Stajnbaher,Frank J. Schenck. "Fast andEasy Multiresidue MethodEmployingAcetonitrile Extraction/Partitioning and Dispersive
Solid-Phase Extractionfor theDetermination of Pesticide Residues inProduce." J. AGACInternational, 2003, vol. 86(22), pp.412-43l.
2. AOACOfficial Method 2007.01, "PesticideResidues in Foods byAcetonitrile Extraction and Partitioning with MagnesiumSulfate."
3.
References notavailable fromRestek
Table III Pesticide percent recoveri es in strawberry extracts tre ated with C1 8 or GCBdSPE, relative to PSAonly.
action/Use
Insecticide
9.67 10265-92-6 Insecticide
11.75 7786-34-7 Insecticide
12.02 o-Phen I henol 90-43-7 Unclassified
g .14 30560-19-1 Insecticide
13.89 1113-02-6 Insecticide
97
107
130
147
119
127
GCB**
116
CASNumber
62-73-7
Organochlorine
Carbamate
Organophosphorus
Organonitrogen
Organonitrogen
Organochlorine
Insecticide
% recovery = RRF 0 8 or GCB X100
333-41-5
Metalaxyl
Dichlofluanid
Thiabendazole
Carbar I
Vinclozolin
Malathion
14.74
RRFPSA
QuEChERS SPETubes
AOAC Method 2QQZ,:L:-:--__-:-- ~~~~'__ Qlrt:...._~!f_
2mLQuEChERSSPE Micro-CentrifugeTube Cleanup of agricultural produce extracts,
Contqills 150mg MagnesiumSulfate and50mg..r ~ l mLsample volume. ....!'!lli:P
Benefits/Uses qty. cat#
P""SA ..±!!.!b..§jilllQ~Q!!dJC!l'h 100-pk. 26124
2mLQuEChERSSPEMicro-CentrifugeTube Cleanup of lm Lsample extract with
filt~..?_Q!:i:l!lJ:.?~cIjQlD9 GrilRhitized Ca bon residualpj gments and sterols. 100- k. 26123 FREE Sample
CQl!t.al.D§.)50mg MaglleslLLIJl.SlJ l ==="--"'",.r"'"' -'-""="'2mL QuEChERS SPE Micro-CentrifugeTube
Cleanup of lmL sample extract with
Contains150mg MagnesiumSulfate, 50mgPSA,and 50mg 08 residual fat. 100-pk. 261_~L Packs Available!
15mL QuEChERSSPECentrifugeTube Cleanup of 6mLsample extract with Toreceive your free sample pack,
Contains900mgMagnesium Su!tJte')..QQ.mg.E.SlI~alld_15Qm9 Graphit"'ized '"- residual pigments and sterols. 50-pk. 26126 . "'"--"'Car"'bo"'n__---'-"~""'-I add-248 to the item number.
PSA-primary and secondary amine exchange material. (One sample per customer)
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