MAE is a process of using microwave energy to heat solvents in contact with a sample in order to partition analytes from the sample matrices into the solvent. In addition to rapid heating and elevated temperature, the process involves disruption of hydrogen bonds, resulting from the dipole rotation of molecules, and migration of dissolved ions, which facilitate the penetration of solvent molecules into matrix. Thus, MAE is endowed with the rapid extraction rate
and high extraction efficiency, which becomes a promising online SP technique for solid samples. Both the static and dynamic MAE techniques have been online coupled with LC. In the static mode, the extract is obtained following the MAE procedures similar to offline methods, and then aspirated by a pump for the further treatment [48]. In the dynamic mode, the extraction is performed in a recirculating system and then the extract in the solvent reservoir is aspirated by a pump for the further treatment.