Introduction to Soxhlet extractor

2009-06-13 20:49 by Ian

My extractor was delivered today, and I chose to test it by extracting essence of eucalyptus using methanol as a solvent.

There are four major pieces of glass in this setup:

Here are some pictures of the device in operation:
Here is depicted the entire extractor setup. You can see the 2000mL boiling flask (dual neck) with the thermometer in the second neck. At the base is the hot plate powering the system.

A close-up of the inside of the extractor body after the first cycle has completed. You can see the thimble and the fact that the foliage is noticeably less-green. Also visible on the left-hand side of the image is the siphon tube and the larger tube that forms the vapor path.

Here is the same thing, but after the second cycle.

Here is a macro shot of the bottom of the siphon tube while the solvent in the extractor body is being returned to the boiling flask. This joint is the top of the boiling flask.

This is what the sample looks like after three complete cycles. What was once wet, oily foliage now looks to be sawdust wet with methanol. This picture was taken after the sample was dried. It is very flammable.

After running four thimbles through the extractor, the boiling point of the solvent was raised to 78°C. It was 68°C when I began. I disassembled the extractor and setup for the distillation to recover the solvent. I recovered 1050mL of solvent for the 1600mL that entered the apparatus. You can see the apothecary jar containing the solvent on the left-hand side of the image.

Roughly 500g of fresh foliage reduced down to about 250mL of extract. The 250mL is comprised of what appears to be an aqueous suspension of formed elements and insoluble oils. I am willing to bet that drying the mixture will result in an oily substance that smells strongly of eucalyptus. I will test that hypothesis later.