Microwave-Enhanced Solvent Extraction of Organics in Environmental Analysis

Microwave-enhanced solvent extraction is a relatively new approach for the extraction of organic pollutants from solid environmental matrices. This approach uses microwave technology to heat organic solvent in contact with the sample in either a sealed (pressurized) or open (atmospheric) vessel. The major advantage of this approach over conventional extraction procedures, such as Soxhlet extraction, is the speed of the process. As well as the principles of microwave heating, the article also describes the instrumentation required to effect the extraction process. Finally, selected applications of microwave-enhanced solvent extraction are described. Applications are divided into extraction from solid matrices and extraction from aqueous matrices. The specific analytes covered include the extraction of polycyclic aromatic hydrocarbons (PAHs), hydrocarbons, polychlorinated biphenyls (PCBs), pesticides and phenols from solid matrices; direct extraction of chlorinated benzenes from aqueous matrices; microwave elution of a range of analytes from solid-phase extraction (SPE) media and, finally, volatile compounds, e.g. benzene, toluene, ethylbenzene and xylenes (BTEX) from aqueous samples. Finally, some recommended operating conditions for the extraction of analytes from solid matrices using pressurized microwave-assisted extraction (MAE) are provided.