Microwave Assisted Extraction

solvent, MAE is very fast since the heat is transferred directly to the solvent (provided that the solvent absorbs microwaves). MAE is promising because: it is fast (e.g. 20-30 min per batch of as many as 12 samples); MAE uses small amounts of solvents as compared to Soxhlet and sonication extraction (30 mL in MAE versus 300-500 mL in Soxhlet extraction); it allows full control of extraction parameters (time, power, temperature); stirring of the sample is possible in MAE; allows high temperature extraction; and no drying agents are needed in MAE since water absorbs microwaves very fast and thus can be used to heat up the matrix. MAE has several drawbacks that contributed to its slow acceptance such as: extracts must be filtered after extraction, which slows down the operation; polar solvents are needed; cleanup of extracts is needed because MAE is very efficient (e.g. 'everything' gets extracted); and the equipment is moderately expensive.

Accelerated solvent extraction is a fairly new extraction method that was approved recently by the U.S. Environmental Protection Agency (EPA) as Method 3545. The extraction is done in a closed-vessel at elevated temperatures (50° to 200°C) and pressures (1500-2000 psi). This technique is attractive because it is fast (e.g. extraction time is approximately 15 min per sample), uses minimal solvent (15-40 mL), no filtration is required after the extraction, and the instrumentation allows extraction in unattended operation. At least 24 samples can be processed sequentially and different sample sizes can be accommodated (e.g. 11, 22, and 33-mL vessels are available).

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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