Quechers Method

The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method of pesticide residue was developed by Michelangelo Anastassiades and Steven Lehotay in 2003 to make the analysis of pesticide residues easier and cheaper. Earlier methods were difficult and required multiple, tedious steps, which were time consuming and required the use of a considerable amount of solvent and did not always cover a wide range of pesticides, necessitating multiple analyses of a sample. Since its original development, the QuEChERS method has been standardized as the AOAC 2007.01, EN 15662 and the mini-multiresidue method. The QuEChERS method allows the analyst to extract pesticides from a homogenized sample in less than 30 minutes, using a minimal amount of solvent, without utilizing any glassware. A broad range of pesticides have been analyzed using QuEChERS, including non-polar, polar and planar pesticides. Pesticides are extracted from interfering matrix components (sugars, fatty acids, sterols, pigments), allowing analysis by GC and LC chromatography. The QuEChERS methodology thus improves the productivity of the laboratory.

Pesticide Analysis: Classical Multiresidue Methods (MRMs) attempt to cover the analysis of as many pesticides as possible from a single sample preparation. More than one analysis is required to cover all the pesticides that one is interested in testing for with the selectivity and sensitivity required for quantification. When the spectrum of the analytes (pesticides) covered in the MRM is broad, fewer additional methods are required to cover all the analytes of interest. The analysis is more efficient in regards to time, personnel and materials. Early MRM were limited to organochloride pesticides (OC) using the FDA Mill’s method (1) in which OC’s and non-polar pesticides were extracted from non-fatty foods with acetonitrile (MeCN), diluted with water and partitioned into non-polar solvent (ether) (2); relatively polar organophosphorus (OP) pesticides were lost in this method. Intermediate MRM increase the analysis range to include polar organophosphate pesticides (OP). These procedures often changed the handling of the MeCN extract with different partitioning, cleanup and determination (analyses) steps.

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