|Microwave Extraction Theory|
In general terms, the overall function of microwave extraction relies on a sample being heated in open or closed vessel at high temperatures . For the process to work in a controlled environment, solvent and sample are placed in closed vessels and microwave power is applied to the cavity. The solvent is chosen in a manner to best perform the extraction and absorb microwave power for the heating process. Microwave energy is absorbed by chemicals with high dielectric potential: i.e. increased polarity in a substance will absorb microwave energy as it rotates resulting in an increase in heat. When a non-polar solvent is needed, a passive heating element can be added to absorb the microwave energy and dissipate the heat to the solvent
Functionally, a solvent or combination is chosen to absorb energy and heat quickly. When performed in a closed-vessel, the power is controlled to heat the solvents above their boiling points and allow the extractions to be performed much faster than older methods. From a simple set-up of multiple vessels inside a microwave cavity, the speed and productivity enhancement has enabled a critical advancement in sample preparation for the organics field.