Food Safety Sample Preparation: QuEChERS Method for Pesticides

Grind the food sample as much as possible to increase surface area and break down cell structure. Keep the sample cold during grinding, preferably using cryogenic milling, to prevent analyte breakdown.

Add the internal standard and extraction solvent (typically acetonitrile) to the centrifuge tube containing the ground sample. Shake the tube vigorously to begin the extraction process.

Add extraction salts and buffers to the centrifuge tube and shake again. These salts and buffers aid partitioning of analytes and control pH to protect sensitive compounds.

Centrifuge the tube to separate the organic layer from the aqueous phase. Transfer the organic layer to a fresh centrifuge tube for the cleanup step.

Add dispersive SPE (dSPE) sorbent to the tube containing the organic extract to remove fats, proteins, chlorophyll, and other unwanted matrix components. Shake the tube to mix thoroughly.

Centrifuge the tube again to separate the cleaned extract from the sorbent. Transfer the final clean, particle-free liquid to a sample vial for analysis.

Consider important recommendations such as hydrating dry samples, using pH buffers for pH-sensitive pesticides, selecting appropriate dSPE sorbent combinations for sample type, and adding analyte protectants before analysis. Consult method specifications for your specific application.