QuEChERS Sample Preparation Method
QuEChERS is a highly efficient type of dispersive solid phase extraction (dSPE) used for sample preparation, designed to be quick, easy, cheap, effective, rugged, and safe. Originally developed in 2002 for the preparation of fruit and vegetable samples for pesticide residue analysis, QuEChERS has since been expanded to accommodate a wide range of chemical classes. These include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and various flame retardants. The method has become widely adopted and is now specified in the official methods of the Association of Analytical Communities (AOAC 2007.01) and the European Committee for Standardization (EN 15662:2008), making it a standard approach in analytical laboratories worldwide.
Overview
QuEChERS Sample Extraction
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. The selection of the solvent is crucial to minimize compound co-extraction. Salts are used during extraction to facilitate phase separation, acting as buffers to adjust pH and remove water from the sample.
QuEChERS Cleanup
Sample cleanup is vital to reduce interference during subsequent analysis, as interferences can damage analytical instrumentation and complicate analyte identification and quantification. Unlike traditional cleanup methods using SPE tubes, QuEChERS facilitates cleanup by mixing bulk amounts of SPE sorbents with the sample extract. The sorbents used in cleanup remove matrix interferences that coextract with the analytes of interest. Common sorbents such as PSA, C18, or GCB (graphitized carbon black) remove substances like sugars, lipids, sterols, organic acids, proteins, carotenoids, chlorophyll, and other pigments before GC-MS/MS or LC-MS/MS analysis. Special Z-Sep sorbents may be required to clean up challenging matrices containing pigments or fats.