Dispersive SPE (dSPE), often referred to as the "QuEChERS"
method (Quick, Easy, Cheap, Effective, Rugged, and Safe), is modern
sample prep technique that is becoming increasingly popular in the area
of multi-residue pesticide analysis in food and agricultural products.
the QuEChERS method, food/agricultural samples are first extracted with
an aqueous miscible solvent (e.g., acetonitrile) in the presence of
high amounts of salts (e.g., sodium chloride and magnesium sulfate)
and/or buffering agents (e.g. citrate) to induce liquid phase separation
and stabilize acid and base labile pesticides, respectively. Upon
shaking and centrifugation, an aliquot of the organic phase is subjected
to further cleanup using SPE. Unlike traditional methods using SPE
tubes, in dispersive SPE, cleanup is facilitated by mixing bulk amounts
of SPE (e.g., Supelclean PSA, ENVI-Carb, and/or Discovery DSC-18) with
the extract. After sample cleanup, the mixture is centrifuged and the
resulting supernatant can either be analyzed directly or can be
subjected to minor further treatment before analysis.
carries a line of vials and centrifuge tubes containing pre-determined
amounts of salts and SPE sorbents to support the most common method
configurations used today.
Suitable for extracting 10-15 g food/agricultural sample. The
high level of salts (e.g. magnesium sulfate) is to induce phase
separation between the acetonitrile and aqueous sample layer.
Supel is a trademark of Sigma-Aldrich Co. LLC