Soxlet extraction

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

6 posts Page 1 of 1
Hi all,

I would like to ask is it Important to set the temperature of socket extraction to near boiling point of the solvents? For example I am using diethyl ether, hence require lower temp? But will it efficient enuff to extract the sample?my testing is phthalate which have higher boiling point.

Thanks
Seet
The solvent *must* boil for the soxhlet apparatus to work. See https://en.wikipedia.org/wiki/Soxhlet_e ... #Operation
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
The simple answer is that the temperature of the extraction is dictated by the boiling point of the solvent you choose. It doesn't get hotter than that. It actually won't be that hot as the boiling solvent cools in the condenser and fills the cavity to soak the sample. The efficiency of the soxhlet extraction is dictated by the solubility of the analyte in the solvent. The extractor is merely a way to perform many serial extractions with clean solvent and not have to babysit it!

If you want your extraction to go faster and more to completion, then choose a higher-boiling solvent. I'd bet that phthalates of all varieties are pretty much infinitely soluble in diethyl ether so you'll be ok on that front. If the phthalates are coming out of some sort of polymeric matrix, you're going to be limited by the diffusion of the phthalate through the plastic. Hotter might be better (if you have the flexibility to change it in your method).
Because of chance of peroxide formation, are you sure that diethyl ether is the best choice of solvent for this?

By the way, even though Soxhlet is a real technique and is semi-unattended, there should be more modern ways to do this.
Other than something like ASE:

https://www.thermofisher.com/us/en/home ... n-ase.html

I can't think of another approach that will quantitatively remove things like phthalates from solid matrices (e.g., plastic formulations). With ASE you have to buy specialized equipment. Most labs with any age on them at all have some Soxhlet extractors sitting around. A little archaic by modern standards but they work.
Microwave extraction works for me for most solid matrices, never tried plastics but if you don't raise too much the temperature it should work i guess.
Diethyl ether should be capable to capture microwaves since it is enough polar, if it doesn't you could add silicon carbide (they sell those) in the vessels.

If you want to be sure that the PTFE vessels are free from phthalates you can use a microwave that allows glass insert like mine.
They are used for one extraction then discarded, no contamination, no carryover (like with ASE), less costs, less solvent consumption than sohxlet, very good recoveries.

It doesn't like high metal content though.

Davide
Davide Balbo from Italy
6 posts Page 1 of 1

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