QuEChERS is a type of dispersive solid phase extraction (dSPE) used for sample preparation. QuEChERS stands for ‘Quick, Easy, Cheap, Effective, Rugged and Safe’. Originally developed to prepare fruit and vegetable samples for pesticide residue analysis, this method is now used to analyze other chemical classes, including PAHs (polycyclic aromatic hydrocarbons), PCBs (polychlorinated biphenyls), PBDEs (polybrominated diphenyl ethers), and flame retardants. The concept was introduced in 2002 and is now specified in official methods of the Association of Analytical Communities (AOAC 2007.01) and European Committee for Standardization (EN 15662:2008).
Solvent extraction techniques are designed to achieve maximum analyte yield from the base matrix. Analytes of interest are extracted from the sample matrix using water-miscible solvents (usually acetonitrile) and high concentrations of salt and/or buffering agents. Solvent selection is important to minimize compound co-extraction. Salts are used in the extraction step to create phase separation. They act as buffers to adjust the pH and remove water from the sample.
Sample cleanup reduces interference during subsequent analysis, as interference can damage analytical instrumentation and complicate analyte identification and quantification. Unlike traditional sample cleanup methods using SPE tubes, in QuEChERS, cleanup is facilitated by mixing bulk amounts of SPE sorbents with the sample extract. Sorbents used in clean up remove matrix interferences that coextract with analytes of interest. The use of PSA, C18 or GCB (graphitized carbon black) sorbents remove sugars, lipids, sterols, organic acids, proteins, carotenoids, chlorophyll, and other pigments prior to a GC-MS/MS or LC-MS/MS analysis. Special Z-Sep sorbents may be needed to cleanup difficult matrices containing pigments or fat.