For solvents heavier than water: chloroform, dichloromethane, and others
Continuous extraction is achieved when fresh solvent dripping (refluxing) from condenser B travels through the aqueous phase (upper layer) in extractor G. As the solvent collects at the bottom of the extractor and reaches the level of tube E, it is siphoned automatically through the open PTFE stopcock D into a heated solvent reservoir attached at C.
With PTFE stopcock D closed, transfer a volume of solvent to the extractor to about the level of the stopcock. Carefully add the aqueous material making sure it does not run out the sidearm. Clamp the extractor onto a rack and attach a suitable flask half-full of solvent at C. The flask should be equipped with boiling chips or a magnetic stirring bar and a source of heat. Open stopcock D and slowly add solvent to the extractor until excess runs over to the flasks via return tube E. Attach a reflux condenser at B and apply heat to the flasks so that rapid reflux is obtained.
For solvents lighter than water: hexanes, ether, ethyl acetate, and others
The diffusion tube adapter A is necessary when extracting with solvents lighter than water. Fresh solvent drips from the condenser into the adapter tube from which solvent diffuses at the bottom of the extractor; then the solvent rises through the aqueous layer because of its lower density. The extraction solvent is recycled to the solvent reservoir via sidearm F.
PTFE stopcock D should be kept closed throughout the extraction procedure. Transfer the aqueous solution into the extractor (being careful not to let it run out the sidearm) and add the organic solvent slowly until the level in the extractor is approximately 1.5 inches below the sidearm. Carefully place diffusion tube adapter A into the extractor, and attach a condenser at B and a flask about 65% full of solvent (and equipped with boiling chips or a magnetic stirring bar) at C. Apply heat to the flask so that rapid reflux is obtained.
Aldrich convertible liquid-liquid continuous extractor
Complete item includes extractor body and diffusion tube adapter (solvent flask (C), is not included and should be purchased separately).